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Pagina principale Clemente's Anatomy Dissector
Clemente's Anatomy DissectorCarmine D. Clemente PhD
Clemente's Anatomy Dissector, Third Edition, is a comprehensive manual of anatomical dissection, organized into 38 chapters covering small, discrete areas of the human body. Each chapter is designed to stand alone, so that instructors can easily adapt the material to their preferred dissection sequence.The book provides more in-depth and detailed explanations for each dissection than any other lab manual, enabling students to self-teach. It correlates surface anatomy to anatomical structures revealed in the dissections, which is important for clinical correlation. Every page is cross-referenced to the newest editions of Clemente's, Grant's, Netter's and Rohen's anatomy atlases.A companion website offers full text online.
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LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page i Aptara Clemente's Anatomy Dissector LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page ii Aptara LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page iii Aptara Clemente's Anatomy Dissector Guides to Individual Dissections in Human Anatomy with Brief Relevant Clinical Notes (Applicable for Most Curricula) Carmine D. Clemente, PhD, DHL Emeritus Professor of Anatomy and Neurobiology (Recalled) UCLA School of Medicine Professor of Surgical Anatomy Charles R. Drew University of Medicine and Science Los Angeles, California THIRD EDITION LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page iv Aptara Acquisitions Editor: Crystal Taylor Product Manager: Julie Montalbano Designer: Terry Mallon Compositor: Aptara, Inc. 3rd Edition Copyright © 2011, 2007, 2002 Lippincott Williams & Wilkins, a Wolters Kluwer business. 351 West Camden Street Baltimore, MD 21201 Two Commerce Square 2001 Market Street Philadelphia, PA 19103 Printed in China. All rights reserved. This book is protected by copyright. No part of this book may be reproduced or transmitted in any form or by any means, including photocopies or scanned-in or other electronic copies, or utilized by any information storage and retrieval system without written permission from the copyright owner, except for brief quotations embodied in critical articles and reviews. Materials appearing in this book prepared by individuals as part of their official duties as U.S. government employees are not covered by the above-mentioned copyright. To request permission, please contact Lippincott Williams & Wilkins at Two Commerce Square, 2001 Market Street, Philadelphia, PA 19103, via e-mail at firstname.lastname@example.com, or via Web site at lww.com (products and services). 9 8 7 6 5 4 3 2 1 Library of Congress Cataloging-in-Publication Data Clemente, Carmine D. Clemente's anatomy dissector : guides to individual dissections in human anatomy with brief relevant clinical notes (applicable for most curricula) / Carmine D. Clemente.–3rd ed. p. ; cm. Other title: Anatomy dissector Includes bibliographical references and index. ISBN 978-1-60831-384-6 (alk. paper) 1. Human dissection–Laboratory manuals. I. Title. II. Title: Anatomy dissector. [DNLM: 1. Anatomy–methods–Laboratory Manuals. 2. Dissection–methods–Laboratory Manuals. QS 25 C626c 2010] QM34.C545 2010 611.0078–dc22 2010002548 DISCLAIMER Care has been taken to confirm the accuracy of the information present and to describe generally accepted practices. However, the authors, editors, and publisher are not responsible for errors or omissions or for any consequences from application of the information in this book and make no warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of the publication. Application of this information in a particular situation remains the professional responsibility of the practitioner; the clinical treatments described and recommended may not be considered absolute and universal recommendations. The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with the current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new or infrequently employed drug. Some drugs and medical devices presented in this publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings. It is the responsibility of the health care providers to ascertain the FDA status of each drug or device planned for use in their clinical practice. To purchase additional copies of this book, call our customer service department at (800) 638-3030 or fax orders to (301) 223-2320. International customers should call (301) 223-2300. Visit Lippincott Williams & Wilkins on the Internet: http://www.lww.com. Lippincott Williams & Wilkins customer service representatives are available from 8:30 am to 6:00 pm, EST. LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page v Aptara Preface Preface to the First Edition One of my objectives in writing this book was to combine a home study exercise with a laboratory dissection experience. Each chapter is a separate dissection and lesson. Indexed to Clemente's Anatomy, A Regional Atlas of the Human Body (4th Edition) with references to three other popular atlases (Grant's Atlas, 11th Edition; Netter's Atlas, 3rd Edition; and Rohen's Atlas, 5th Edition), the student learns the step-by-step dissection procedure for the laboratory along with relevant text information that enhances the laboratory work. At home, the learning process can be repeated by reading the text of each chapter and, following the dissection procedure, by simultaneously viewing the line drawings of this book and the relevant pages or plates in one of the referenced atlases. The dissection directions are detailed beyond those of other currently used laboratory manuals, allowing students the opportunity to dissect on their own if they wish to do so, yet the text is brief and stresses essentials. Usually, each dissection will require one laboratory period of 2.5 to 3 hours. Exceptions to this may be the dissections of the pelvis and perineum, which may require some more time. The descriptions for these latter two dissections are similar in format. They include sections to be dissected similarly in both sexes and then special instructions required for individual dissections in male and female cadavers. One need not defend again the value of dissecting the human body in schools of medicine and the other health professions. Experience through the centuries has proved its value in introducing the student to the study of medicine and its allied professions. Some have claimed that often "irrelevant" information was stressed in anatomy dissection courses. I have tried to select a dissection method that exposed essential structures in the most straightforward manner. No part of the body is summarily excluded, allowing the book to be of value for various types of curricula. One departure from other dissection guides introduced in this book and suggested by my colleague, the late Professor David Maxwell, is the dissection of the posterior triangle of the neck immediately following that of the axilla but before the remainder of the upper limb. This allows the student to see the source of the neurovascular structures that supply the shoulder, arm, forearm, and hand. This was changed in 2nd and subsequent edition. In this book, significant attention is paid to surface anatomy in virtually every relevant dissection. This aspect of anatomy is of prime importance for its clinical implications. Because the dissections are described in separate chapters, the study guide can be used in virtually any of the varied curricula and course sequences in our health science schools. The sequence of dissection chapters follows from the pectoral region to the upper limb, thorax, abdomen, pelvis and perineum, lower limb, back, neck, and head. Additionally, the separate dissection chapters and their subheadings can readily be selected to meet the needs of a systems curriculum or to a classical regional sequence that commences in parts of the body other than the pectoral and upper limb regions. Many of the line drawings in this book were done by the artist Ms. Jill Penkhus in Los Angeles. Many others were produced under the direction of Professor Gene Colborn several years ago at the Medical College of Georgia for the Urban & Schwarzenberg Publishing Company. Still others were drawn by Ms. Patricia Vetter. I am most grateful to Ms. Penkhus, Ms. Vetter, and especially to Professor Colborn for their contributions. My appreciation is also extended to Mr. Timothy Satterfield and Ms. Susan Katz at Lippincott Williams & Wilkins for their patience as well as Ms. Ulita Lushycky for her most effective managing of the manuscript. Finally, but by no means least, I am most grateful to Julie, my wife, who has spent many hours at the computer during the development and eventual completion of the manuscript. Los Angeles, 2002 Preface to the Second and Third Edition My appreciation goes to the many faculty and students who have used this dissector. Its wide acceptance not only in the United States but in foreign countries as well has been most gratifying. Several significant changes have been made. One is that in the first edition, dissection of the posterior triangle of the neck (which contains the neurovascular structures for the upper limb) was introduced just prior to dissections on the pectoral girdle and upper limb. In subsequent editions, the posterior triangle of the neck was shifted to the section on neck and head dissections v LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page vi Aptara vi PREFACE (29) just prior to the anterior triangle dissection. This change was made only because most courses use this latter dissection sequence and not because it especially makes better anatomic sense. Since publication of the first edition of this dissector, new editions of the Grant's, Netter's, and Rohen atlases have appeared. Thus, the 3rd edition is now cross-referenced with the new 6th edition of the Clemente atlas, the 12th edition of the Grant's atlas, the 4th edition of Netter, and the 7th edition of Rohen. Many new figures have been introduced, several of which have come from the 30th American edition of Gray's Anatomy, which I edited and which appeared in 1985. Many positive comments have been received from course chairs that each dissection is a separate "chapter" in the book, making it easy in their assignments to the students. This format has also been appreciated by chairs whose courses do not include dissections of the entire body or, perhaps, even certain dissections within specific body regions. I have also attempted to edit some descriptive material in the various dissections and have added paragraphs on clinical relevance. My appreciation again goes to Professor Gene Colborn for several drawings in this book, along with artists Jill Penkhus and Patricia Vetter. At Lippincott Williams & Wilkins, my appreciation is extended to Ms. Betty Sun and especially to Ms. Crystal Taylor and Ariel Winter. At UCLA my many thanks are extended to my Gross Anatomy colleagues Professors Shaleen Metten, Robin Fisher, Guido Zampighi, David Hovda, Charles Olmstead, Anna Taylor, Yau Shi Lin, Jayc Sedlmayer, and Francesco Chiappelli for their suggestions and for their use of this book in their courses. Los Angeles, 2010 LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page vii Aptara How to Use This Book This dissector has been designed to assist students of medicine and health professions in performing comprehensive and efficient dissections. The text has the following features: Each chapter can be used on its own, as a separate dissection and lesson, in the sequence most appropriate for any anatomy course. Therefore, the arrangement of the content makes this dissector applicable to varied curricula. Basic information on surface anatomy and related preparatory techniques precedes the dissecting instructions. This text is printed in black on white background. Dissection procedures are printed in black on a shaded red background. Figure references are color-coded in red, so the student can easily establish the connection between figures and dissecting steps. Important structures are set in boldface in text. Some cautionary statements are set in capitalized letters. References to Clemente's atlas are embedded in the text. However, cross-references to other major atlases are placed in a middle column next to the appropriate procedure. Red arrows clearly indicate to which column the references correspond. The beginning of each dissection lists the referenced atlases, their corresponding edition numbers, and information indicating whether the numbers refer to plates or pages. Clemente's Dissector is referenced to the following atlases: Anatomy: A Regional Atlas of the Human Body, 6th Edition Carmine D. Clemente Lippincott Williams & Wilkins, 2010 Grant's Atlas of Anatomy, 12th Edition Anne M.R. Agur Arthur F. Dalley II, Editors Lippincott Williams & Wilkins, 2009 Netter's Atlas of Human Anatomy, 4th Edition Saunders/Elsevier, 2006 Color Atlas of Anatomy: A Photographic Study of the Human Body, 7th Edition Johannes W. Rohen Chihiro Yokochi Elke Lütjen-Drecoll Lippincott Williams & Wilkins, 2010 vii LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page viii Aptara LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page ix Aptara Contents Preface v How to Use This Book vii DISSECTION 1 Introductory Session and Surface Anatomy of the Thorax, Shoulder, and Upper Limb 1 I. II. III. IV. V. General Comments and Care of the Cadaver 1 Dissection Instruments 1 The Anatomic Position 1 Anatomic Planes 2 Surface Anatomy of the Anterior Thorax, Shoulder, Axilla, and Upper Limb 2 DISSECTION 2 Mammary Gland and Pectoral Region 8 I. II. III. IV. V. Observe Other Cadavers 8 Reflection of Skin 8 Mammary Gland 9 Reflection of the Superficial Fascia 12 Pectoral Muscles and Other Structures 13 II. Cut Scapular Attachments of Trapezius and Deltoid Muscles; the Supraspinous and Infraspinous Fossae 24 III. Lateral Border of Scapula; Triangular and Quadrangular Spaces; Axillary Nerve and Deltoid Region 27 IV. Anastomoses Around the Scapula 29 V. Posterior (Extensor) Compartment of the Arm 30 DISSECTION 5 Anterior Brachial Region; Cubital Fossa; Anterior Forearm and Wrist 34 I. Surface Anatomy; Skin Incisions; Superficial Veins and Nerves 34 II. Anterior Compartment of the Arm: Muscles, Vessels, and Nerves 37 III. The Cubital Fossa 40 IV. Anterior Forearm Muscles, Vessels, and Nerves 40 V. Tendons, Vessels, and Nerves on the Anterior Wrist 44 DISSECTION 6 Palmar Aspect of the Hand 46 DISSECTION 3 Deep Pectoral Region and Axilla 16 I. Deep Pectoral Region 16 II. Axilla 17 DISSECTION 4 Scapular and Deltoid Regions; Posterior Compartment of the Arm 23 I. Surface Anatomy; Skin Incisions; Cutaneous Nerves 23 I. Surface Anatomy; Skin Incisions; the Palmar Aponeurosis and Digital Vessels and Nerves 46 II. Ulnar Artery and Nerve; Fascial Spaces of the Hand 49 III. Flexor Retinaculum; Flexor Tendons and Synovial and Fibrous Sheaths; Dissection of Middle Finger 50 IV. Thenar Muscles; Movements of the Thumb; Dissection of the Distal Thumb; the Hypothenar Muscles 53 V. Adductor Pollicis Muscle; Deep Palmar Arch; Deep Branch of the Ulnar Nerve; Interosseous Muscles 54 ix LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page x Aptara x CONTENTS DISSECTION 7 DISSECTION 11 Posterior Compartment of Forearm and Dorsum of the Hand 56 Thorax III: The Heart: Blood Circulation; Heart Surface Anatomy; Blood Supply, Chambers, and Conducting System of the Heart 97 I. General Introduction 56 II. Surface Anatomy; Removal of Skin; Superficial Veins and Nerves 56 III. Muscles of the Extensor Compartment of the Forearm 58 IV. Extensor Retinaculum; Extensor Synovial Sheaths; Structures Across the Dorsum of the Wrist 61 V. Arteries and Nerves on Dorsum of Hand; Dorsal Interosseous Muscles 63 I. II. III. IV. V. Circulation of the Blood: General Comments 97 Surface Anatomy of the Heart 97 Arteries and Veins of the Heart 99 Chambers of the Heart 101 Conducting System of the Heart 106 DISSECTION 12 DISSECTION 8 Joints of the Upper Extremity 65 I. II. III. IV. V. Joints of the Shoulder Region 65 Joints at the Elbow Region 68 The Middle and Distal Radioulnar Joints 71 Joints at the Wrist 72 Metacarpophalangeal and Interphalangeal Joints 74 Thorax IV: Posterior Mediastinum; Sympathetic Trunks; Diaphragm from Above; Superior Mediastinum 109 I. II. III. IV. Posterior Mediastinum 109 Sympathetic Trunks and Splanchnic Nerves 112 Diaphragm 113 Superior Mediastinum 113 DISSECTION 13 DISSECTION 9 Anterior Abdominal Wall 118 Thorax I: Anterior Thoracic Wall 76 I. Surface Anatomy; Thoracic Vertebrae, Ribs, and Respiratory Movements; Projections of Heart and Lungs onto the Thoracic Wall 76 II. Anterior Thoracic Wall: Muscles, Vessels, and Nerves 82 III. Removal of the Anterior Thoracic Wall 84 IV. Pleura and Thoracic Viscera in Place; Removal of the Lungs 85 DISSECTION 10 Thorax II: Pleura and Lungs; Anterior Mediastinum; Middle Mediastinum and Pericardium; Removal of the Heart 88 I. Pleural Reflections 88 II. Lungs 89 III. Mediastinum and Its Subdivisions; Anterior Mediastinum 93 IV. Middle Mediastinum and Pericardium 94 I. Surface Anatomy of the Anterior Abdominal Wall 118 II. Skin Incisions; Superficial Fascia; Cutaneous Vessels and Nerves 119 III. Flat Muscles and Nerves of the Anterior Abdominal Wall 122 IV. Rectus Abdominis Muscle and Sheath; Epigastric Anastomosis 124 V. Inguinal Region 126 VI. Scrotum; Spermatic Cord; Testis 128 VII. Female Inguinal Canal, Round Ligament of the Uterus, and the Labia Majora 129 DISSECTION 14 Abdominal Cavity I: Topography of the Abdominal Viscera and Reflections of the Peritoneum 131 I. Exposure of Abdominal Cavity; Inner Surface of Abdominal Wall; Falciform and Round Ligaments 131 II. Peritoneum and Abdominal Viscera In Situ 133 III. Peritoneal Cavity; Greater and Lesser Peritoneal Sacs 137 LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page xi Aptara CONTENTS DISSECTION 15 DISSECTION 19 Abdominal Cavity II: Rotation of the Gut; Dissection of Stomach; Liver; Duodenum and Pancreas; Spleen 140 The Perineum: Male and Female 192 I. Embryologic Events Related to the Development of the Gastrointestinal Tract 140 II. Dissection of the Stomach, Liver and Gall Bladder, Duodenum and Pancreas, and Spleen 143 I. II. III. IV. xi General Information and Surface Anatomy 192 Anal Triangle and Region 194 Male Urogenital Triangle and Region 197 Female Urogenital Triangle and Region 203 DISSECTION 20 DISSECTION 16 Abdominal Cavity III: Intestinal Tract from Duodenojejunal Junction to Rectum 152 The Gluteal Region, Posterior Thigh, and Popliteal Fossa 209 I. Superior and Inferior Mesenteric Vessels 152 II. Jejunum and Ileum 156 III. Large Intestine 157 I. Surface Anatomy; Skin Incisions; Cutaneous Innervation 209 II. Gluteal Region 212 III. Posterior Compartment of the Thigh 216 IV. Popliteal Fossa 220 DISSECTION 17 DISSECTION 21 Abdominal Cavity IV: Posterior Abdominal Wall 161 Anterior and Medial Compartments of the Thigh 223 I. Gonadal Vessels, Kidneys, Ureters, and Suprarenal Glands 161 II. Muscles of the Posterior Abdominal Wall and the Lumbar Plexus 165 III. The Diaphragm from the Abdominal Aspect 169 IV. Abdominal Aorta; Inferior Vena Cava; Lumbar Sympathetic Chain 170 I. Surface Anatomy; Superficial Vessels and Nerves 223 II. Femoral Triangle; Femoral Vessels and Their Branches; Adductor Canal; Femoral Nerve 226 III. Quadriceps Femoris Muscle and Its Motor Nerves 228 IV. The Medial (Adductor) Region of the Thigh 230 DISSECTION 18 DISSECTION 22 The Pelvis: Male and Female 173 Anterior and Lateral Compartments of the Leg and Dorsum of the Foot 234 I. General Features Found in Both the Male and Female Pelvis 173 II. Male Pelvic Organs: Urinary Bladder and Ureters; Seminal Vesicles and Ductus Deferens; Prostate Gland and Prostatic Urethra; Rectum 179 III. Female Pelvic Organs: Urinary Bladder, Ureters, and Urethra; Ovaries and Uterine Tubes; Uterus and Vagina; Rectum 182 IV. Lateral Pelvic Wall and Floor: Vessels, Nerves, and Muscles 185 I. Surface Anatomy; Superficial Vessels and Nerves; Anterior Leg, Ankle, and Dorsum of the Foot 236 II. Anterior Compartment of the Leg 239 III. Lateral Compartment of the Leg 243 IV. Ankle Region and Dorsum of the Foot 243 LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page xii Aptara xii CONTENTS DISSECTION 23 The Posterior Leg and Sole of the Foot 248 IV. External Nose 306 V. Anterior Orbital Region 307 VI. Superficial Vessels and Nerves of the Face 308 VII. Superficial Structures on the Lateral Face 312 I. Surface Anatomy 248 II. Incisions and Superficial Dissection of the Posterior Leg 249 III. Posterior Compartment: Muscles, Vessels, and Nerves 249 IV. Plantar Aspect of the Foot 253 DISSECTION 28 DISSECTION 24 I. II. III. IV. Joints of the Lower Limb 260 I. Sacroiliac Joint 260 II. Symphysis Pubis 263 III. Hip Joint 264 IV. Knee Joint 268 V. Tibiofibular Joints 271 VI. Ankle Joint (Talocrural Joint) 272 VII. Joints Within the Foot 275 DISSECTION 25 Superficial and Deep Back; Spinal Cord 280 I. Posterior Primary Rami; Trapezius and Latissimus Dorsi; Rhomboids and Levator Scapulae 280 II. Intermediate Muscles of the Back 286 III. Deep Muscles of the Back 287 IV. Vertebral Canal and Spinal Cord 290 DISSECTION 26 Back of the Neck and the Suboccipital Region 297 I. II. III. IV. Posterior Skull and First Two Cervical Vertebrae 297 Dorsal Rami of the Cervical Nerves 298 Suboccipital Triangle 300 Vertebral Artery 300 DISSECTION 27 The Superficial Face and Anterior Scalp 303 I. Bony Landmarks and Surface Anatomy of the Face and Forehead 303 II. Skin Incisions; Reflections of Skin Flaps 304 III. External Muscles of the Mouth 305 Temporal and Infratemporal Regions (Deep Face) 316 Veins of the Temporal and Retromandibular Regions 316 Masseter and Temporalis Muscles 318 Infratemporal Fossa and Its Contents 319 Temporomandibular Joint 325 DISSECTION 29 Posterior Triangle of the Neck 328 I. II. III. IV. Boundaries of the Posterior Triangle; Skin Incisions 328 Superficial Vessels and Nerves 330 Omohyoid and Other Posterior Triangle Muscles 332 Expose the Subclavian Vessels and Brachial Plexus By Removing the Middle Third of the Clavicle 332 V. Subclavian Vessels 332 VI. Cervical Part of the Brachial Plexus 334 DISSECTION 30 Anterior Triangle of the Neck 337 I. II. III. IV. Surface Landmarks and Triangles of the Neck 337 Superficial Anterior Cervical Structures 339 Infrahyoid Strap Muscles; the Ansa Cervicalis 341 Thyroid Gland; Superior and Inferior Thyroid Arteries; Recurrent Laryngeal Nerves; Parathyroid Glands 343 V. Structures Within or Adjacent to the Carotid Triangle 345 VI. Suprahyoid Region 348 VII. Deep Structures at the Root of the Neck 349 DISSECTION 31 Scalp; Floor of the Cranial Cavity; Base of the Brain 353 I. II. III. IV. V. Scalp 353 Removal of Skull Cap and Wedge of Occipital Bone 356 Meninges; Removal of the Brain 357 Base of Skull: Bony Markings; Foramina 360 Arterial Blood Supply to the Brain 362 LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page xiii Aptara CONTENTS DISSECTION 32 DISSECTION 36 The Orbit: Superior and Anterior Dissections 366 Nasopharynx; Oropharynx (Inner Wall); Palate; Mouth and Tongue 403 I. The Bony Orbit 366 II. The Orbit from Above 367 III. The Orbit from the Anterior Approach 373 DISSECTION 33 Craniovertebral Joints and Prevertebral Region 380 I. Basilar Part of the Occipital Bone; the Atlas and Axis 380 II. Median and Lateral Atlantoaxial Joints; Atlantooccipital Joints 381 III. Separation of the Head and Cervical Viscera from the Vertebral Column 384 IV. The Prevertebral Region 384 DISSECTION 34 I. Nasopharynx 403 II. Soft Palate from Above: Levator and Tensor Palati Muscles 404 III. Internal Structure of the Oropharynx 404 IV. Hard Palate Dissected from Its Oral Surface 406 V. Oral Cavity and Tongue 407 DISSECTION 37 The Larynx and Laryngopharynx 415 I. The Skeleton of the Larynx 415 II. Surface Anatomy of the Anterior Larynx 416 III. The Posterior Larynx; the Laryngopharynx; the Lateral Laryngeal Muscles 418 IV. The Interior of the Larynx 421 The Pharynx: External and Internal Dissections 386 I. Structure and Relationships of the Pharynx; Vagus and Glossopharyngeal Nerves 386 II. Pharyngeal Constrictor Muscles 388 III. Interior of the Pharynx 390 DISSECTION 35 The Nasal Cavity and Paranasal Sinuses in the Bisected Head 394 I. II. III. IV. V. Bisection of the Head 394 Nasal Septum 395 Roof and Floor of the Nasal Cavity 396 Lateral Wall of the Nasal Cavity 397 Pterygopalatine Ganglion; Greater and Lesser Palatine Nerves and Vessels 399 VI. Paranasal Sinuses 400 xiii DISSECTION 38 The External and Middle Ear and the Semicircular Canals of the Inner Ear 425 I. The External Ear 425 II. The Lateral (Mastoid) Approach to the Facial Nerve; Semicircular Canals; Tympanic Cavity 427 III. The Superior (Cranial Cavity) Approach to the Middle Ear 430 INDEX 433 LWBK529-FM_i-xiv.qxd 3/9/10 2:19 PM Page xiv Aptara LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 1 Aptara Inc DISSECTION 1 Introductory Session and Surface Anatomy of the Thorax, Shoulder, and Upper Limb ATLAS KEY: Clemente Atlas, 6th Edition = Atlas Plate # Grant's Atlas, 12th Edition = Grant's Page # Netter's Atlas, 4th Edition = Netter's Plate # Rohen Atlas, 7th Edition = Rohen Page # I. General Comments and Care of the Cadaver The first dissection period of a course in human anatomy proves to be a moving experience. It is inspiring simply to realize that the privilege exists to dissect the remains of another human being and that society today recognizes and approves the intrinsic value of human dissection in the education of the health professional. This was not always the case, and the history of anatomic dissection shows that a long struggle was waged through several centuries by courageous medical scientists to achieve our current state of enlightenment. It is important for the student to appreciate that the cadaver to be dissected was once a living person and that it commands both admiration and respect. Most bodies used for dissection in the United States and Canada are willed to medical schools by public-spirited citizens in the community. Even properly embalmed cadavers require special attention. The hands, feet, and head of the cadaver must be wrapped in cloth (such as cheesecloth) that is liberally moistened with embalming fluid. This cloth should be moistened periodically. After each dissection period, the dissected regions should not be allowed to dry by remaining exposed to air. The skin and superficial fascia are usually dissected as separate layers and will be retained as large tissue flaps to cover previously dissected regions. As dissection progresses, regions of the body already studied should be kept moistened so that they may be reviewed later. II. Dissection Instruments (Figure 1-1) Different types of dissection instruments are available. Students should obtain the following instruments: A. A scalpel handle that can receive detachable, large size #20 or #21, rounded contour blades. B. Two pairs of tissue forceps (51/2 to 6 inches in length): one with rounded blunt ends and the other with sharply ridged (rat-toothed) ends in order to grasp tissues securely. C. Two pairs of scissors: one should be 5 to 6 inches in length and have either sharp ends or one sharp and one rounded end; the other should be a pair of fine dissection scissors with two sharp ends. D. A blunt inflexible metal dental probe. E. A grease marking pencil (one to a table) for outlining skin incisions. III. The Anatomic Position The anatomic position is the standard position of the body that is used universally to describe the location of anatomic structures. The body is in this position when the person is standing upright with the anterior surface 1 LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 2 Aptara Inc 2 DISSECTION 1 A FIGURE 1-1 B C D E F G Dissection instruments to be used. A, B, and C, forceps; D, blunt probe; E, scalpel; F and G, scissors. of the body facing forward and the posterior surface oriented dorsally. The lower limbs and feet are together and oriented anteriorly. The upper limbs are by the side of the body with the palmar surface of the hands oriented anteriorly (Figure 1-2). IV. Anatomic Planes With the body in the anatomic position, structures and regions are often described in one or another plane. The midsagittal (or median) plane divides the body into right and left halves (Figure 1-3A). Planes parallel to the midsagittal plane are referred to as parasagittal (paramedian) planes. Vertical planes at right angles to the midsagittal plane are called coronal planes. A coronal plane down the middle of the body divides the body into anterior and posterior halves. Transverse or horizontal planes course across the body at right angles to the median and coronal planes (Figure 1-3). V. Surface Anatomy of the Anterior Thorax, Shoulder, Axilla, and Upper Limb During this first laboratory session, students should inspect and palpate structures on the surface of the body and identify certain bony landmarks and other anatomic features. Clinical Relevance It is important to have a thorough knowledge of the bony structures on the anterior thoracic wall because their locations can often be correlated to deeper structures and organs in the chest. Realize that descriptions of the incision sites through the chest wall to approach deeper structures or the identifications of surface lesions often use bony landmarks for precise communication. One male student at each dissection table is to strip to the waist, so that the following surface structures can be identified: A. Anterior Thorax. 1. Jugular (or suprasternal) notch: At the superior border of the sternum between the two clavicles (ATLAS PLATES 139, 140, 141). 2. Sternal angle (of Louis): A transverse ridge on the sternum approximately 4 to 5 cm (1.5 to 2 inches) inferior to the suprasternal notch where the manubrium and body of the sternum fuse (ATLAS PLATES 140, 141). Note that the 2nd ribs are attached to the sternum lateral to the sternal angle. LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 3 Aptara Inc Introductory Session and Surface Anatomy of the Thorax, Shoulder, and Upper Limb 3 Arm Anterior or ventral surface of the body Ulna (medial) aspect of the forearm Posterior or dorsal surface of the body Radial (lateral) aspect of the forearm Forearm Gluteal region Supinated hand (palmar surface anterior) Thigh Fibular (lateral) aspect of the leg Leg Tibial (medial) aspect of the leg Dorsum of the foot FIGURE 1-2 The anatomic position. A. Anterior view. B. Lateral view. B A 3. Manubrium of the sternum: Located between the suprasternal notch and the sternal angle (ATLAS PLATES 140, 141). Palpate the attachment of the clavicle to the manubrium at the sternoclavicular joint. 6. Costal margins: Note on a skeleton that ribs 8, 9, and 10 join to form the cartilaginous lower costal margin of the rib cage (ATLAS PLATES 4, 5) and that ribs 11 and 12 do not attach to the sternum. 4. Body of sternum: Extends for about 10 cm (4 inches) inferior to the sternal angle. Note on a skeleton that ribs 3, 4, 5, and 6 attach to the body of the sternum (ATLAS PLATE 141). 7. Infrasternal angle: The acute angle below the sternum between the costal margins. 5. Xiphoid process: Palpate the inferior extremity of the sternum in the midline for the xiphoid process. It attaches to the inferior border of the body of the sternum. The 7th ribs join the sternum at the xiphisternal junction (ATLAS PLATE 141). Grant's 2, 10, 12 Netter's 185, 186 Rohen 369, 370 8. Palpate the clavicle and the sternoclavicular joint (ATLAS PLATES 115, 140). Visualize several imaginary vertical lines on the chest wall (Figure 1-4 and ATLAS PLATE 2). a. Midsternal line: Descends in the midline over the sternum. b. Parasternal line: Any line that descends parallel to the sternum. LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 4 Aptara Inc 4 DISSECTION 1 Coronal plane Midsagittal plane Parasagittal plane Horizontal plane Horizontal plane through the lower limb Coronal plane through the lower limb A FIGURE 1-3 B Planes used to define views of body structures. A. Frontal view. B. Lateral view. c. Midclavicular line: Descends from the middle of the clavicle over the anterior thoracic wall. This line often courses near the nipple in the male or the young female (Figure 1-4). d. Midaxillary line: A vertical line from the middle of the axillary fossa (armpit) down the lateral thorax. 9. Palpate the 2nd ribs through the skin. Feel the softer tissue in the 2nd intercostal space below the 2nd rib. Palpate the 3rd through the 7th ribs and intercostal spaces in this manner (ATLAS PLATE 140). 10. Observe the nipple. In most men and young women it is located either over the 4th intercostal space or over the 5th rib (Figure 1-4). The location of the nipple on the chest wall in older women may vary, because aging of connective tissue results in sagging of the breasts (ATLAS PLATES 2–5). B. Anterior and Lateral Shoulder and the Axilla. LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 5 Aptara Inc Introductory Session and Surface Anatomy of the Thorax, Shoulder, and Upper Limb Parasternal line Midsternal line 5 Midclavicular line Midaxillary line Clavicle Sternal angle (of Louis) Acromion 1 2 3 Nipple 4 Head of humerus 5 6 7 8 FIGURE 1-4 Imaginary vertical lines on skeleton of thoracic cage. Clinical Relevance 3. More difficult to feel is the coracoid process. Press inferior and slightly medial to the acromioclavicular joint (ATLAS PLATES 112, 114–116) in a depression, the infraclavicular fossa (Figure 1-5). Within the anterior and lateral shoulder region is located the glenohumeral (shoulder) joint. Additionally, anterior and posterior folds define a cone-shaped region called the axilla (armpit). Located as a strut between the sternum and the acromion is the clavicle, one of the most frequently fractured bones in the body. Dislocations of the humerus at the shoulder joint usually result from direct falls. Frequently, the head of the humerus is dislocated through the joint capsule inferiorly and medially below the coracoid process. This painful injury also results in a loss of the normally smooth contour of the lateral shoulder. 1. At the jugular notch, palpate the sternoclavicular joint and follow the clavicle laterally to its articulation with the scapula called the acromioclavicular joint (ATLAS PLATES 112, 114–116). 2. Palpate the rounded contour at the tip of the shoulder. The underlying bony structure is the acromion of the scapula (ATLAS PLATES 34, 44, 119). 4. With the upper limb abducted, feel the hollow of the axillary fossa (armpit). Grasp the anterior axillary fold, consisting of the pectoralis major and minor muscles. Grasp the posterior axillary fold, formed by the subscapularis, teres major, and latissimus dorsi muscles (ATLAS PLATE 34). Grant's 10, 499, 536 Netter's 185, 421–423 Rohen 368, 370 5. Note the smooth contour of the shoulder formed by the deltoid muscle (ATLAS PLATES 29, 34). On a skeleton, find the greater and lesser tubercles on the head of the humerus. On your laboratory partner, palpate the greater tubercle deep to the soft tissue of the deltoid. Feel for the lesser tubercle on the anterior aspect of the humerus (ATLAS PLATES 113, 115). Between the two tubercles, palpate the intertubercular (or bicipital) sulcus containing the tendon of the long head of the biceps muscle. C. The Arm and Forearm (Figure 1-5). LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 6 Aptara Inc 6 DISSECTION 1 Clavicle Grant's 496, 497, 558, 585, 589 Netter's 420, 421, 435, 440 Rohen 372–375 Infraclavicular fossa Acromion Anterior axillary fold Arm (brachium) Areola Nipple Breast 1. Between the elbow and the shoulder joint is the arm (or brachium), and the forearm (or antebrachium) extends between the wrist and the elbow (ATLAS PLATE 1). Flex the forearm and observe the belly of the biceps brachii muscle. This muscle is active both in flexion of the forearm and in supination (turning the hand over, so that the palmar surface lies anterior). 2. Note the bicipital furrows along the sides of the biceps muscle (ATLAS PLATE 34). Deep to the furrow course the brachial artery, its accompanying veins, and the median nerve. Feel for the arterial pulse through the skin. Identify the cephalic vein coursing along the lateral aspect of the arm (ATLAS PLATES 36, 41). 3. Palpate the triceps muscle on the posterior arm during extension of the forearm. At the elbow locate three bony structures posteriorly, the olecranon of the ulna, felt between the medial and lateral epicondyles of the humerus (ATLAS PLATES 34, 36, 44). Cubital fossa Forearm (antebrachium) With the forearm fully extended, note that the two condyles and the olecranon lie in a straight line. Flex the forearm to a right angle with the arm, and note that the olecranon lies distal to the two condyles. In full flexion, the olecranon lies anterior to the two condyles. These relationships are lost if the ulna is dislocated. Wrist Thenar eminence Thumb Palm Hypothenar eminence Photograph of upper limb and breast in a young woman. FIGURE 1-5 Clinical Relevance Fractures of the humerus or of the radius or ulna frequenty result from direct trauma or from falls. These fractures can injure or even sever large nerves, thereby disrupting neuromuscular functions. Fractures of the shaft of the humerus could injure the radial nerve, whereas fractures in the upper forearm can injure the ulnar nerve, especially near the posterior aspect of the elbow joint. Blood is frequently drawn from veins (antecubital vein) on the anterior aspect of the elbow. Realize that deep to the superficial vein in the antecubital fossa are located the brachial artery and median nerve. 4. Feel the ulnar nerve behind the medial epicondyle (ATLAS PLATE 66). The sensation felt by palpating across this nerve will remind you of the "crazy bone" feeling in the hand when you bump your elbow. 5. In the supinated forearm position, palpate the cubital fossa anterior to the elbow joint (ATLAS PLATE 41). Feel the muscle mass bounding the fossa laterally. This consists of the brachioradialis muscle and the underlying extensor compartment muscles of the forearm (ATLAS PLATES 80, 81). Below the medial epicondyle, palpate the pronator teres muscle and the common origin of the flexor compartment muscles of the forearm. These form the medial boundary of the cubital fossa. Observe the median cubital vein superficially in the cubital fossa and realize that the venous pattern is variable at this site (ATLAS PLATE 41). Deep to the median cubital vein, palpate the aponeurosis of biceps brachii muscle (bicipital aponeurosis). When the biceps muscle is LWBK529-C01_001-007.qxd 3/8/10 10:09PM Page 7 Aptara Inc Introductory Session and Surface Anatomy of the Thorax, Shoulder, and Upper Limb and realize that this nerve courses into the thumb muscles at that point. Injury of the nerve will impair functions of the thumb, especially in performing opposition to the other fingers. tensed, this aponeurosis protects the underlying brachial artery and median nerve (ATLAS PLATES 70, 76). 6. Palpate the ulna from the olecranon distally to the wrist. When supinated, the ulna is the medial forearm bone at the wrist joint. Feel the styloid process, which is the distal end of the ulna. On the lateral side of the forearm, the radius lies deep to muscles, but the bone can be felt subcutaneously 4 inches above the wrist. Palpate the distal end of the radius, also called the styloid process (ATLAS PLATES 122, 127). D. Wrist and Hand. Clinical Relevance Coursing into the palm deep to a strong ligament is the median nerve along with the tendons of the flexors digitorum superficialis and profundus within the carpal tunnel. Overuse of these tendons or the development of an inflammatory condition within this tunnel can cause pressure on the median nerve, resulting in weakness or loss of function of the thenar muscles of the thumb. Perhaps the most important nerve in the hand is the recurrent branch of the median nerve. Feel at your wrist the most distal point of the radius. Project distally into the hand a distance of about 11⁄2 inches (or 4 cm) 7 Grant's 518, 519, 558, 585, 589 Netter's 450, 451, 456 Rohen 375–377 1. Flex and extend the hand at the wrist. Note that you can bend your hand medially (ulnar flexion) and slightly laterally (radial flexion) at the wrist. 2. On a skeleton, observe the 8 carpal (wrist) bones, 5 metacarpal bones, and 14 phalanges that form the bony structures of the wrist and hand (ATLAS PLATES 128, 129). Make a strong fist. This involves flexion at joints between the phalanges and between the metacarpal bones and the proximal phalanges of the fingers. 3. Place one of your hands alongside an articulated skeleton of a hand of the same side. Note that the transverse creases at the wrist, hand, and fingers are related to the joints. The three principal creases in the palm overlay the metacarpal bones (Figure 1-6). Observe that the skin of the palm is taut and cannot be displaced across the underlying tissue. In contrast, note the "looseness" of the skin on the dorsum of the hand where the large veins of the upper limb commence. Distal interphalangeal creases Proximal interphalangeal creases Metacarpophalangeal creases FIGURE 1-6 Palmar aspect of the right hand indicating longitudinal and transverse creases. Distal transverse palmar crease Proximal transverse palmar crease Ulnar longitudinal crease Radial longitudinal crease Transverse carpal creases LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 8 Aptara DISSECTION 2 Mammary Gland and Pectoral Region Objectives 1 Remove the skin and superficial fascia from the pectoral region. 2 Dissect the nipple of the female mammary gland to see some of the lactiferous sinuses and ducts. 3 Study the blood supply and lymphatic drainage of the breast from figures in the Atlas. ATLAS KEY: Clemente Atlas, 6th Edition = Atlas Plate # Grant's Atlas, 12th Edition = Grant's Page # Netter's Atlas, 4th Edition = Netter's Plate # Rohen Atlas, 7th Edition = Rohen Page # I. Observe Other Cadavers The primary objective of human dissection is to separate structures in the body and thereby observe their threedimensional relationships. You must understand the meaning of terms such as medial and lateral, superior and inferior, anterior and posterior (dorsal and ventral), and proximal and distal because these are used to describe the relationships of structures to each other. Also, you must know what is meant by a sagittal or median sagittal plane, a coronal plane, and a transverse plane. 8 4 Learn the course of a typical spinal nerve and learn how to dissect several lateral and anterior cutaneous branches. 5 Expose the pectoralis major muscle and the medial and lateral pectoral nerves that supply it. 6 Dissect the thoracoacromial artery and cephalic vein as they penetrate the clavipectoral fascia. Take advantage of viewing the other cadavers in the laboratory. Because variation is a biologic constant, the precise location of structures as described in textbooks may not be duplicated in your cadaver. Vessels (and especially the superficial veins) are among the most variable of structures to be dissected. The large and important arteries are usually less variable than superficial veins, whereas the major nerve trunks, the muscles, and organs are typically similar from one body to the next. Size, body build, and gender account for certain differences in organ relationships. Make it a habit to see and learn as much as you can in the dissection hall. II. Reflection of Skin Before reflecting the skin of the anterior thorax, feel the jugular (suprasternal) notch, the manubrium, body and xiphoid process of the sternum, the sternal angle, the acromion, and the clavicle. Also note the position of the nipple, and in males (or young females), identify LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 9 Aptara Mammary Gland and Pectoral Region the rib or specific intercostal space on which the nipple is located. Epidermis Superficial fascia Dermal papillae A. Initial Incisions. Make a midline incision (Figure 2-1: A–C) through the skin from the jugular notch to the xiphoid process. From this incision, make three other incisions laterally: 1. Between the upper border of the manubrium to the acromion (tip of the shoulder) along the clavicle (Figure 2-1: A–D). Extend this incision down the arm about 5 inches (Figure 2-1: D–G) and then around the arm (Figure 2-1: G, H). FIGURE 2-2 Suggested manual technique for dissecting the skin from the superficial fascia. 2. From the midline laterally (encircling the pigmented areola) to the midaxillary line about 3 inches below the anterior axillary fold (Figure 2-1: B–E). many small pock marks, or pits, called dermal papillae. Keep the two skin flaps attached laterally. They will be replaced over the chest to prevent drying of the cadaver surface. 3. From the xiphisternal junction to the midaxillary line over the 6th rib (Figure 2-1: C–F). Leave the nipple and areola attached to the underlying tissue. In males, note the location of the nipple on the anterior thoracic wall and proceed to reflect the superficial fascia (ATLAS PLATES 2, 3). Observe that the female breast lies completely in the superficial fascia. Any dissection of the mammary gland should be done prior to the reflection of the superficial fascia. B. Reflection of Skin. Reflect the skin from the underlying superficial fascia. This is best done by beginning at the jugular notch (Point A in Figure 2-1) and proceeding laterally. Hold the scalpel edge at a slight angle to the underlying superficial fascia. Apply traction to the overlying skin by making an incision in the reflected skin through which the index finger of the free hand can be inserted as shown in Figure 2-2. III. Mammary Gland (Atlas Plates 3–5) When properly done, little or no fat will be adherent to the deep surface of the skin, which will show The mammary gland, or breast, develops as a specialization of approximately 15 modified sweat glands, all of which open onto the surface of the nipple by way of the lactiferous ducts. Note that the fully formed breast extends between the lateral sternal line and the midaxillary or anterior axillary lines and lies over the anterior chest wall between the 2nd and 6th ribs. D A G B E H C F FIGURE 2-1 9 Incision lines for the pectoral region. Grant's 4–9 Netter's 182–184 Rohen 208, 290 Dissect the breast by removing the fat that lies between several of the connective tissue septa called the suspensory ligaments of Cooper. Do this either with the handle of the scalpel or with a large pair of forceps (ATLAS PLATE 6 #6.1). Note that these ligaments are attached to the skin superficially and to the deep fascia posterior to the breast. Dissect the deep surface of the areola and nipple and identify one or more of the lactiferous ducts. These open on the nipple and are arranged in a radial pattern beneath the surface of the pigmented skin. Trace one duct more deeply where it enlarges to form lactiferous sinuses (Figure 2-3). LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 10 Aptara 10 DISSECTION 2 Pectoralis major muscle Latissimus dorsi muscle Loculi in the connective tissue Ampullae Nipple Lactiferous ducts Areola Lobules Fat Serratus anterior muscle FIGURE 2-3 Dissection of the lateral half of the right breast during a period of lactation. (From Clemente CD. Gray's Anatomy. 30th American Edition. Philadelphia: Lea and Febiger, 1985.) Clinical Relevance Pay particular attention to the blood supply (Figure 2-4) and the venous and lymphatic drainage (Figure 2-5 and ATLAS PLATES 3–5) of the breast because of their importance as routes for the spread of cancer cells. The arteries that supply the breasts are derived from the axillary artery, the intercostal arteries, and the internal thoracic artery. The lateral thoracic branch of the axillary artery descends in the chest and gives off the lateral mammary branches, whereas medial mammary branches come from the internal thoracic artery as it descends just lateral to the sternum (see Figure 2-4). Intercostal arteries send perforating branches through the 2nd to the 5th intercostal spaces to supply blood to the deep regions of the breast. Venous channels form an anastomotic ring around the nipple from which larger vessels are formed laterally and medially to drain into the internal thoracic vein. These vessels flow into the axillary and subclavian veins. LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 11 Aptara Mammary Gland and Pectoral Region 11 Pectoralis major muscle Axillary artery Subclavian artery Deltoid muscle Internal thoracic artery Lateral thoracic artery The lateral and medial mammary branches that supply the breast from the lateral and internal thoracic arteries. FIGURE 2-4 Lateral mammary branches Deltopectoral nodes FIGURE 2-5 Lymphatic drainage from the Central axillary nodes Medial mammary branches Deep cervical nodes Deep axillary nodes Internal thoracic nodes right breast. Anterior axillary nodes along lateral thoracic vessels Lymph drainage to the opposite breast and to the diaphragm LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 12 Aptara 12 DISSECTION 2 Lymphatic vessels from the mammary gland are numerous and of great clinical importance (Figure 2-5). Channels from the deep regions of the gland course in the connective tissue between the glandular lobules and along the lactiferous ducts. From the central part of the gland and from the skin deep to the areola and nipple is the subareolar plexus. From these sources, collecting vessels course laterally and superiorly to the anterior axillary or pectoral nodes along the course of the lateral thoracic vessels and to the central and deep or apical axillary nodes. Although most lymph drains superiorly and laterally, some channels drain medially along parasternal or internal thoracic nodes (Figure 2-5). Lymph channels from the inferior and medial parts of the breast may communicate with diaphragmatic and abdominal vessels as well as with channels across the midline to the opposite breast. With a probe and forceps, separate structures within the superficial fascia. Identify one or two anterior and lateral cutaneous branches of the intercostal thoracic nerves and the supraclavicular nerves (ATLAS PLATES 13, 16). Find these structures as follows: A. Anterior Cutaneous Branches. Identify the 2nd, 3rd, and 4th ribs lateral to the sternum by probing through the fascia to the hard surface of the costal cartilages. In the 3rd intercostal space 1 cm lateral to the sternum, probe for the anterior cutaneous branch of the 3rd thoracic nerve usually accompanied by a small artery and vein (ATLAS PLATE 13). B. Lateral Cutaneous Branches (Figure 2-7). Palpate the 3rd and 4th ribs in the midaxillary line. In the 3rd intercostal space, dissect the lateral cutaneous branch of the 3rd intercostal nerve. Note other lateral cutaneous branches in the intercostal spaces inferiorly (Figure 2-6). Larger than the anterior cutaneous branches, these nerves are also accompanied by lateral cutaneous branches of the intercostal vessels. Find the intercostobrachial nerve (T2), which emerges in the 2nd intercostal space and courses toward the axillary fossa and arm (ATLAS PLATES 13, 26, 27). IV. Reflection of the Superficial Fascia The superficial fascia is to be reflected as a single layer, but only after some of the anterior and lateral cutaneous branches of the spinal nerves are located. Learn the general pattern and course of a typical spinal nerve (Figure 2-6 and ATLAS PLATE 10). Lateral branch Grant's 3, 20, 495 Netter's 188, 424, 429 Rohen 207, 209, 394, 406 Medial branch C. Supraclavicular Nerves (Figure 2-7). Derived from the 3rd and 4th cervical nerves, these nerves descend in the superficial fascia and supply the skin over the clavicle and the first two intercostal spaces. To find them: Dorsal root (sensory) 1. Make a 4-inch transverse incision through the superficial fascia only, commencing 1 inch lateral to the sternal angle. Cut only deep enough to see the deep fascia covering the darker muscle fibers of the pectoralis major. Dorsal root ganglion Dorsal primary ramus Spinal nerve (mixed) Ventral primary ramus Posterior branch Ventral root (motor) Sympathetic ganglion Anterior branch Rami communicantes Ventral primary ramus Lateral cutaneous branch Anterior cutaneous branch Lateral branch FIGURE 2-6 2. Elevate the superficial fascia above the transverse cut and identify strands of a thin sheet of muscle on the inner surface of the superficial fascia, called the platysma muscle (ATLAS PLATES 521, 529). Medial branch A typical spinal nerve and its branches. 3. Between this muscle and the deep fascia, locate at least one or more supraclavicular nerves (ATLAS PLATES 13, 16). LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 13 Aptara Mammary Gland and Pectoral Region muscles, the vessels and nerves that supply them, and the pectoral and clavipectoral fasciae. Supraclavicular nerves (C3, 4, 5) T2 T2 T5 Lateral cutaneous nerves Anterior cutaneous nerves T12 L1 T10 L1 FIGURE 2-7 13 Cutaneous branches of spinal nerves supply. D. On finding the cutaneous nerves, reflect the superficial fascia laterally. Make a longitudinal incision just lateral to the sternum through the superficial fascia and only as deep as the deep fascia covering the pectoralis major muscle. As you reflect the superficial fascia laterally, retain some of the cutaneous nerves for future review. Observe the fibers of the pectoralis major muscle beneath the layer of deep fascia over the muscle (pectoral fascia). V. Pectoral Muscles and Other Structures In addition to containing the mammary gland, the pectoral region contains the pectoralis major and minor Grant's 3, 496 Netter's 188, 424, 429 Rohen 207, 209, 394, 406 A. The Pectoralis Major Muscle. Clean the surface of the pectoralis major muscle and identify its clavicular, sternocostal, and abdominal parts (ATLAS PLATE 11). Within the groove that separates the pectoralis major from the deltoid muscle, find the cephalic vein (variable in size). This groove is the deltopectoral triangle (ATLAS PLATE 17), the three sides of which are the deltoid muscle, the pectoralis major muscle, and the clavicle. Its apex is directed inferiorly. Free the cephalic vein and note that it disappears deep to the pectoralis major muscle. Do not sever it at this time. Locate the separation between the sternal and clavicular heads of the pectoralis major muscle. Widen this separation with a probe through the depth of the muscle to the underlying chest wall. Insert your index finger upward beneath the clavicular head and carefully separate the clavicular head from the underlying clavipectoral fascia. Feel for the vessels and nerves that penetrate this fascia. These are branches of the lateral pectoral nerve and the pectoral branches of the thoracoacromial artery and vein (ATLAS PLATE 22 #22.1). Cut the clavicular head of the pectoralis major muscle close to its origin on the clavicle and reflect it laterally (Figure 2-8). Observe the curved line of the attachment of the sternocostal and abdominal heads of the pectoralis major muscle (ATLAS PLATE 17). Feel for branches of the medial pectoral nerve penetrating through the pectoralis minor to enter the deep surface of the pectoralis major. Look for a branch of the lateral pectoral nerve entering the upper part of the sternocostal head. Realize that the lateral and medial pectoral nerves are branches from the lateral and medial cords of the brachial plexus; hence, their names. Do not be disturbed that the medial pectoral nerve is located at a site on the anterior thoracic wall somewhat lateral to the lateral pectoral nerve. The lateral pectoral nerve supplies only the pectoralis major muscle, whereas the medial pectoral nerve supplies both the pectoralis major and minor muscles. After freeing the pectoralis major muscle from its underlying fascial attachments, make a curved cut through it 1.5 inches from its sternal attachment LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 14 Aptara 14 DISSECTION 2 Trapezius muscle Pectoralis minor muscle Sternocleidomastoid muscle Deltoid muscle Suprasternal notch Manubrium Sternal angle Body of sternum Pectoralis major muscle (reflected) (clavicular head) Pectoralis major muscle (sternocostal head) Xiphoid process FIGURE 2-8 The incision line for the pectoralis major muscle. (Figure 2-8). Reflect the cut ends of the muscle and identify the branches of the nerves and of the thoracoacromial artery that supply the muscle (ATLAS PLATES 22 #22.1, 24 #24.1, 27). Grant's 500, 508 Netter's 188, 428 Rohen 207, 407 B. Clavipectoral Fascia. Deep to the pectoralis major muscle, observe a broad sheet of deep fascia called the clavipectoral fascia (Figure 2-9). Extending down from the clavicle, it continues inferiorly to the axillary fascia. Observe that it encases the subclavius muscle, just below the clavicle, and the pectoralis minor muscle more laterally. Identify the following structures penetrating the clavipectoral fascia: 1. The cephalic vein coursing into the axillary vein; 2. The thoracoacromial artery; 3. The lateral pectoral nerve and its branches. Grant's 508 Netter's 428, 429 Rohen 207, 385 C. The Pectoralis Minor Muscle. Note that the pectoralis minor attaches to the coracoid process of the scapula proximally and the 2nd, 3rd, 4th, and 5th ribs on the thorax distally (ATLAS PLATE 22 #22.2). Identify branches of the medial pectoral nerve that pierce the muscle from the underlying medial cord of the brachial plexus, thereby gaining access to the overlying pectoralis major. Clinical Relevance Sternal angle: The site of articulation of the manubrium and the body of the sternum has several important relationships. (a) At this site the second rib articulates with the sternum and that allows each of the lower ribs and intercostal spaces to be counted; LWBK529-C02_008-015.qxd 3/9/10 1:11 PM Page 15 Aptara Mammary Gland and Pectoral Region Branches of Clavicular branch thoracoacromial Acromial branch artery Deltoid branch 15 Clavipectoral fascia (costocoracoid membrane part) Thoracoacromial artery Cephalic vein Pectoral branch of thoracoacromial artery Pectoralis minor muscle Clavipectoral fascia Pectoralis major muscle Pectoralis major muscle Superficial fascia Deep pectoral fascia FIGURE 2-9 The clavipectoral fascia deep to the pectoralis major muscle. (b) A transverse plane at the sternal angle intersects the vertebral column between the 4th and 5th thoracic vertebrae. At this plane is the bifurcation of the trachea and the commencement of the ascending aorta from the left ventricle. Thoracostomy by needle or tube through an intercostal space is often necessary for removal of air or fluids from the pleural cavity, thereby reducing a pneumothorax or hemothorax to restore breathing. Bone marrow biopsy is often achieved from the sternum, a bone that is rich in bone marrow and relatively easy to tap. LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 16 Aptara DISSECTION 3 Deep Pectoral Region and Axilla Objectives 1 Identify the axillary vein and some of its tributaries. 2 Understand why the pectoralis minor is called the "key to the axilla." 3 Identify the branches of the axillary artery. 4 Find the M of the brachial plexus and dissect the cords of the plexus and its peripheral nerves. 5 Identify the subscapularis, latissimus dorsi, teres major, serratus anterior, coracobrachialis muscles, and the short head of the biceps brachii. ATLAS KEY: Clemente Atlas, 6th Edition = Atlas Plate # Grant's Atlas, 12th Edition = Grant's Page # Netter's Atlas, 4th Edition = Netter's Plate # Rohen Atlas, 7th Edition = Rohen Page # I. Deep Pectoral Region Through the deep pectoral region and axilla course the nerves, arteries, and veins that supply the upper limb (ATLAS PLATE 27). Of additional importance are the lymphatic channels and nodes in these regions. They receive lymph from the upper extremity, but more significantly from the anterior thorax and—of special importance—from the mammary gland in women (ATLAS PLATES 8, 20). The axillary vein receives blood from the upper limb (including the shoulder) as well as from the pectoral region. It commences near the lower border of the teres major muscle at the junction of the basilic and brachial veins that ascend in the arm. The axillary vein becomes the subclavian vein as it ascends beneath the clavicle. 16 Grant's 501, 503, 757 Netter's 188, 256, 428, 483 Rohen 170, 171, 398 Grant's 500, 509 Netter's 427–429, 434 Rohen 207, 284, 407, 411–413 A. Axillary Vein. Abduct the upper limb of the cadaver nearly to a 45° angle. Remove fat lateral and medial to the pectoralis minor muscle and uncover the large axillary vein and the underlying axillary artery and cords of the brachial plexus (ATLAS PLATES 27, 31, 58). With your index finger, loosen the neurovascular structures deep to the pectoralis minor muscle. Trace the cephalic vein medial to the coracoid process and follow it to its junction with the axillary vein. Also identify the thoracoacromial branch of the axillary artery and the lateral pectoral nerve penetrating through the fascia from below (ATLAS PLATE 22.1). Separate the axillary vein from the underlying axillary artery and cords of the brachial plexus. Remove fat within the axilla down as far as the latissimus dorsi and teres major muscles. Because veins retain some coagulated blood after death, they often appear darker than the accompanying arteries. Cut away the smaller veins that flow into the axillary vein; however, do not cut the arteries that accompany these tributaries. LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 17 Aptara Deep Pectoral Region and Axilla 17 Coracoid process Acromion Subclavius muscle Clavicle Greater tubercle Lesser tubercle Humerus 1 Manubrium 2 Sternal angle 3 Body of sternum Scapula 4 5 Pectoralis minor muscle 6 Xiphoid process 7 8 FIGURE 3-1 B. Reflect the Pectoralis Minor Muscle and Remove the Axillary Vein. Reflect the pectoralis minor muscle by severing its distal attachments to the 2nd, 3rd, 4th, and 5th ribs, but maintain its attachment to the coracoid process (Figure 3-1). Relax the upper limb by slightly adducting it and dissect through the axillary fascia with a probe. This fascia partially surrounds the axillary vein but more completely envelops the axillary artery and cords of the brachial plexus. Sever and remove the axillary vein and its tributaries from the clavicle to the tendons of the latissimus dorsi and teres major muscles. This will better expose the artery and nerves. DO NOT CUT THE AXILLARY ARTERY, ANY OF The pectoralis minor muscle. ITS BRANCHES, OR THE CORDS OF THE BRACHIAL PLEXUS SURROUNDING THE AXILLARY ARTERY WHILE REMOVING THE VEINS. II. Axilla The axilla is a cone-shaped or pyramidal region that lies deep to the pectoral muscles, superficial to the scapula and between the upper part of the brachium (arm) and the lateral chest wall. Its anterior wall is the pectoralis major and minor muscles and forms the anterior axillary fold; its posterior wall is formed by the teres major, latissimus dorsi, and subscapular muscles and comprises the posterior axillary fold; its medial wall is LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 18 Aptara 18 DISSECTION 3 Superior angle of scapula Clavicle Manubrium 2nd rib Lateral border of scapula Body of sternum Medial border of scapula Inferior angle of scapula 5th rib Serratus anterior muscle 8th rib FIGURE 3-2 The serratus anterior muscle. the upper six ribs and intercostal spaces and is covered by the serratus anterior muscle (ATLAS PLATES 18.2, 22.2); and the lateral angle consists of the intertubercular groove or sulcus (bicipital groove) on the surgical neck of the humerus. 4. Teres major: its tendon is located deep to that of the latissimus dorsi and with the subscapularis forms the posterior axillary fold (ATLAS PLATES 58, 60). A. Identify the Following Muscles Associated With the Axillary Region. 5. Serratus anterior: extends from the upper 8 or 9 ribs to the medial (or vertebral) border of the scapula (Figure 3-2). Probe its lateral surface longitudinally and find the long thoracic nerve (C5, C6, and C7). 1. Pectoralis major and minor: form the anterior axillary fold. 2. Subscapularis: occupies the subscapular fossa and inserts on the lesser tubercle of the humerus (ATLAS PLATES 31 #31.1). 3. Latissimus dorsi: ascends from the back of the trunk to attach on the medial lip of the bicipital groove of the humerus (ATLAS PLATES 18.2, 22.2). Grant's 509–511 Netter's 188, 424, 428, 429 Rohen 385, 386, 407, 415 6. Short head of biceps brachii: extends from the coracoid process and joins the long head of the biceps in the arm (ATLAS PLATES 54, 56). 7. Coracobrachialis: also arises from the coracoid process and inserts on the humerus (ATLAS PLATES 54, 57). The musculocutaneous nerve usually pierces the coracobrachialis muscle to enter the anterior arm region. LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 19 Aptara Deep Pectoral Region and Axilla 19 Thoracoacromial artery Anterior humeral circumflex artery Posterior humeral circumflex artery Supreme thoracic artery FIGURE 3-3 The axillary artery and its branches. Circumflex scapular artery Subscapular artery Thoracodorsal artery Lateral thoracic artery and descends along the side of the chest (ATLAS PLATES 26, 27). In approximately 70% of specimens, it arises either from the thoracoacromial or from the subscapular artery. B. Axillary Artery and Branches (Figure 3-3). Replace the pectoralis minor and note that it divides the axillary artery into three parts (ATLAS PLATE 24.1). The first part lies medial to the pectoralis minor and has one branch. The second part courses beneath the pectoralis minor muscle and has two branches, and the third part lies lateral to the pectoralis minor (as far as the lower margin of the teres major muscle) and has three branches. The axillary artery becomes the brachial artery below the teres major muscle. Realize that some variability in the pattern of these branches exists. Find the branches of the axillary artery as follows (Figure 3-3 and ATLAS PLATE 24.1): 1. From the first part: a. Superior (supreme) thoracic artery: a small vessel arising just below the clavicle to supply the upper one or two intercostal spaces. 2. From the second part (Figure 3-4): a. Thoracoacromial artery: a short trunk that quickly divides into pectoral, acromial, clavicular, and deltoid branches. It frequently branches near the medial border of the pectoralis minor (ATLAS PLATE 22.1). b. Lateral thoracic artery: in 30% of specimens it arises from the axillary artery near the lateral border of the pectoralis minor Grant's 486, 508, 509 Netter's 183, 188, 427–429 Rohen 170, 396, 397, 411, 412 3. From the third part (ATLAS PLATES 20, 24): a. Subscapular artery: usually the largest branch from the axillary artery that is found on the anterior surface of the subscapularis muscle or near its axillary border. After 11⁄2 inches, it divides into the scapular circumflex branch that courses around the lateral border of the scapula in the triangular space, and the thoracodorsal artery that descends to the latissimus dorsi muscle with the thoracodorsal nerve. With a probe, pull the trunk of the axillary artery medially away from the humerus to see the following circumflex vessels: b. Anterior humeral circumflex artery: it is small and arises near the upper border of the teres major muscle. It passes anteriorly around the humerus. c. Posterior humeral circumflex artery: larger than the anterior, it passes posteriorly around the humerus. With a probe, trace the posterior humeral circumflex artery to the quadrangular space, through which it is accompanied by the axillary nerve to achieve LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 20 Aptara 20 DISSECTION 3 Subclavius muscle Axillary sheath Thoracoacromial artery Lateral pectoral nerve Pectoral branch of thoracoacromial artery Pectoralis major muscle Medial pectoral nerve Lateral thoracic artery Thoracodorsal artery and nerve FIGURE 3-4 The lateral pectoral nerve and some branches of the thoracoacromial artery coursing between the pectoralis major and minor muscles. Pectoralis minor muscle Serratus anterior muscle the lateral pectoral nerve, which either comes off the lateral cord directly or arises higher in the axilla from divisions that form the lateral cord (Figure 3-4). the dorsal shoulder region. See ATLAS PLATES 32, 33 for triangular and quadrangular spaces. C. Brachial Plexus and Its Branches (Figures 3-5 and 3-6). 2. Note that the lateral cord contributes a large branch that helps form the median nerve. Use ATLAS PLATES 46–48 to learn the general pattern of formation of the brachial plexus. This dissection is concerned with the infraclavicular (or axillary) part of the brachial plexus. This consists of the lateral, medial, and posterior cords of the plexus, and the terminal nerves that branch from them. The cervical portion of the brachial plexus will be studied with the posterior triangle of the neck. 1. Identify the lateral cord of the brachial plexus by finding the musculocutaneous nerve, which is the most lateral nerve of the plexus and the nerve that penetrates the coracobrachialis muscle (ATLAS PLATES 58, 59). Follow the musculocutaneous nerve proximally to its point of origin from the lateral cord. Also find 3. Identify the median nerve and note that it receives another large contribution from the medial cord. Thus, the median nerve most often is formed by two large nerve trunks, one contributed from the lateral and the other from the medial cord. 4. From the medial cord, identify its other terminal branch, the ulnar nerve. Grant's 506, 508, 509 Netter's 183, 429, 430, 433 Rohen 186, 396, 411, 415 5. Place your index finger behind the musculocutaneous, median, and ulnar nerves and elevate them slightly from the axillary artery. Notice that their pattern resembles the letter M (ATLAS PLATE 48). Return to the medial cord and find three other nerves that arise LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 21 Aptara Deep Pectoral Region and Axilla Pectoralis major muscle Musculocutaneous nerve Pectoralis minor muscle Median nerve 21 Axillary artery and vein Medial pectoral nerve Coracobrachialis muscle Biceps brachii muscle Serratus anterior muscle Ulnar nerve Latissimus dorsi muscle Subscapular artery Long thoracic nerve Thoracodorsal nerve Subscapularis muscle FIGURE 3-5 The axillary artery and vein and the musculocutaneous, median, and ulnar nerve branches from the medial and lateral cords of the brachial plexus. from it above the origin of the ulnar nerve. These are: a. the medial antebrachial cutaneous nerve: this large sensory nerve to the forearm is sometimes confused with the ulnar nerve. b. the medial brachial cutaneous nerve: smaller than the preceding nerve, it arises slightly higher on the medial cord and often sends a communicating branch to the intercostobrachial nerve (T2) that passes through the 2nd intercostal space in the midaxillary line (ATLAS PLATES 26, 27). c. the medial pectoral nerve: trace this nerve back to the medial cord from its site of penetration of the pectoralis minor muscle. Clinical Relevance Thoracic outlet syndrome: The apex of the coneshaped axillary region is formed by three bones: the clavicle, scapula, and first rib. At this site the brachial vessels and the nerves of the brachial plexus might become compressed against the bones. Frequently this pressure results in symptoms related to spinal segments C7 and C8 (inferior trunk of the brachial plexus) and results in pain related to the distribution of the ulnar and medial antebrachial cutaneous nerves along the medial aspect of the forearm and hand. Klumpke's paralysis: This syndrome is usually the result of a birth injury caused by the excessive abduction of the upper limb, which injures the C8 and T1 roots of the brachial plexus. The resulting deformity includes a "claw hand" owing to trauma to the inferior trunk of the brachial plexus (C8, T1) and consequent LWBK529-C03_016-022.qxd 3/9/10 1:12 PM Page 22 Aptara 22 DISSECTION 3 3 TRUNKS 5 ROOTS Suprascapular nerve Erb's point C4 5 TERMINAL NERVES 6 DIVISIONS Axillary 3 CORDS C5 r Uppe C6 Musculocutaneous Lateral Middle Median Radial C7 Posterior Lower C8 Medial Ulnar T1 Medial pectoral nerve Medial antebrachial cutaneous nerve Lateral pectoral nerve Upper subscapular nerve Medial brachial Thoracodorsal nerve cutaneous nerve Lower subscapular nerve FIGURE 3-6 Long thoracic nerve The roots, trunks, divisions, cords, and peripheral branches of the brachial plexus. paralysis of muscles supplied by the ulnar nerve. Some flexion at the wrist occurs, but considerable flexion of the medial three fingers gives a clawlike appearance to the hand. Winged scapula: Characteristic of this condition is the projection outward of the medial border of the scapula on the posterior chest wall in a manner that resembles a wing.This condition is caused by a weakness or paralysis of the serratus anterior muscle that holds the vertebral border of the scapula close to the posterior chest. At times when surgery is performed to remove lymph nodes along the course of the long thoracic nerve in women with breast cancer, inadvertent severance or trauma to this nerve on the lateral chest wall results in a winged scapula. Erb-Duchenne paralysis: This syndrome is a partial paralysis of the brachial plexus that is usually the result of a birth injury. It involves the superior roots (or trunk) of the brachial plexus (C5, C6). The resultant deformity includes pronation of the forearm, extension at the elbow joint, and adduction of the upper limb. The pronated forearm and flexed hand projecting posteriorly is reminiscent of the hand of a waiter expecting a tip (waiter's tip position). 6. Locate the posterior cord of the brachial plexus behind the axillary artery. Identify its two terminal nerves, the large radial nerve and the axillary nerve. Trace the axillary nerve to the quadrangular space, which it traverses with the posterior humeral circumflex artery. 7. Higher on the posterior cord find three other nerves that course inferiorly. The upper subscapular nerve supplies the subscapularis muscle; the lower subscapular nerve supplies both the subscapularis and teres major muscles. Between these two nerves, locate the thoracodorsal nerve that descends with the thoracodorsal vessels to supply the latissimus dorsi muscle. Clinical Relevance Grant's 510 Netter's 430 Cervical rib: In 1 of 200 persons, an anomalous bony rib arises from the transverse process of the 7th cervical vertebra. Called a "cervical rib," it can cause pressure on the inferior trunk of the brachial plexus or the subclavian artery, resulting in a thoracic outlet syndrome. Central venous line: Most often the right subclavian or right internal jugular vein is selected to place a catheter into the venous system. Visualized radiographically, the catheter is guided into the right brachiocephalic vein, then into the superior vena cava, and finally into the right atrium of the heart. A central venous line catheter is at times required to deliver therapeutic drugs or to measure venous pressure directly in the right atrium. LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 23 Aptara Inc DISSECTION 4 Scapular and Deltoid Regions; Posterior Compartment of the Arm Objectives 1 Study the surface anatomy of the upper back and posterior scapular region. 2 Detach the trapezius and the deltoid muscles from the spine of the scapula, expose the supraspinatus muscle, and locate the suprascapular vessels and nerve. 3 Dissect the infraspinatus muscle and identify the teres major and minor muscles. 4 Dissect the quadrangular and triangular spaces and find the axillary nerve, posterior humeral circumflex artery, and circumflex scapular artery. 5 Dissect the posterior compartment of the arm and expose the heads of the triceps muscle. 6 Separate the medial and lateral heads of the triceps brachii and follow the radial nerve and deep brachial artery around the shaft of the humerus. ATLAS KEY: A. Surface Anatomy and Bony Landmarks. Clemente Atlas, 6th Edition = Atlas Plate # Before making the skin incision, review the surface anatomy of the back and palpate the following several bony landmarks on one of your colleagues or on the cadaver or articulated skeleton. Grant's Atlas, 12th Edition = Grant's Page # Netter's Atlas, 4th Edition = Netter's Plate # Rohen Atlas, 7th Edition = Rohen Page # I. Surface Anatomy; Skin Incisions; Cutaneous Nerves Place the cadaver face down (prone) and elevate the shoulders by means of a wooden block inserted under the anterior thorax. Partially abduct the upper limbs (to approximately 45) and realize that the pectoral girdle is attached to the axial skeleton completely by muscles posteriorly and by muscles and one bony articulation anteriorly, the sternoclavicular joint. Grant's 97, 395, 296, 613, 614 Netter's 8, 9, 174–176 Rohen 21, 29, 33, 192, 193 1. External occipital protuberance: Found in the midline on the back of the skull (ATLAS PLATES 373, 589). Identify bony ridges, called superior nuchal lines, that extend laterally from the protuberance and its most central point, called the inion. 2. Spinous process of the 7th cervical vertebra: Pass your index finger in the midline down from the skull over the dorsal aspect of the cervical vertebrae. The first prominent bony process felt is the spinous process of the C7 vertebra, called the vertebra prominens 23 LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 24 Aptara Inc 24 DISSECTION 4 skin along the posterior midline extending from the external occipital protuberance to 1 inch below the inferior angle of the scapula (Figure 4-1, A to C). Make two lateral incisions on each side at right angles to the midline cut as shown in Figure 4-1, B to E and F and C to G and H. (ATLAS PLATES 371.1, 389.1). A fibroelastic membrane called the ligamentum nuchae covers the other cervical spines, making them less palpable. 3. Study the location of the scapula over the posterior thoracic wall on a skeleton (ATLAS PLATE 141.1) and note its superior, inferior, and lateral angles. Palpate the spine of the scapula and follow it laterally to the acromion (ATLAS PLATE 371.1). Note that the medial (vertebral) border is parallel to the vertebral column and that the lateral (axillary) border is oriented toward the axillary fossa. Grant's 321, 513 Netter's 174, 424 Rohen 226, 227 4. Palpate the posterior part of the iliac crest, a curved bony ridge below the waist (ATLAS PLATES 323, 326.2, 373). It terminates at the posterior superior iliac spine on the surface of which is a dimple in the skin on each side. C. Cutaneous Nerves of Back (ATLAS PLATE 452, Figure 4-2). B. Skin Incisions and Skin Reflection (Figure 4-1). To dissect the posterior scapular region, remove the skin from the back of the neck and upper half of the back. Make an incision through the A A Initially, remove only the skin by reflecting it from the underlying superficial fascia in four flaps. Next, reflect the superficial fascia from the deep fascia that overlies the dark fibers of the trapezius muscle above and the latissimus dorsi muscle below (ATLAS PLATE 373) and look for branches of the cutaneous nerves of the back (ATLAS PLATE 382). Grant's 321 Netter's 177 Rohen 229, 234 A B Dissect several of the segmentally arranged posterior primary rami of the thoracic nerves. They are frequently accompanied by cutaneous blood vessels and they traverse the trapezius and latissimus dorsi muscles to become superficial, yet they DO NOT supply these muscles either with motor or with sensory innervation. To locate these nerves, probe the fascia overlying the trapezius muscle 1 inch lateral to the spinous processes of the thoracic vertebrae. Realize that most of the thoracic nerves pierce the trapezius muscle, and, after becoming superficial, they course laterally in the superficial fascia across the back (Figure 4-2). Now remove the superficial fascia over the scapular and deltoid regions, preserving short lengths of the dissected cutaneous nerves. E F G I C D H II. Cut Scapular Attachments of Trapezius and Deltoid Muscles; the Supraspinous and Infraspinous Fossae To uncover the muscles within the fossae above and below the spine of the scapula, detach the trapezius and deltoid muscles but only from the acromion and spine of the scapula (ATLAS PLATES 32, 373). J FIGURE 4-1 Skin incision for the back. Grant's 513, 515, 516, 528 Netter's 174, 177, 434, 432 Rohen 226, 234, 403 A. Reflection of Trapezius and Deltoid Muscles. Palpate the upper border of the trapezius and palpate the acromion and scapular spine. Cut the attachment of the trapezius along the medial margin of the acromion and along the superior aspect LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 25 Aptara Inc Scapular and Deltoid Regions; Posterior Compartment of the Arm scapula posteriorly (ATLAS PLATE 44). This muscle's fibers converge inferiorly to attach to the deltoid tuberosity. Cut the origin of the deltoid from the scapular spine and acromion and free its posterior border inferiorly to the deltoid tuberosity, leaving the clavicular origin intact. Reflect the deltoid anteriorly to uncover the underlying infraspinatus and teres minor muscles (Figure 4-3 and ATLAS PLATES 32, 60). C1 3 4 5 6 7 8 T1 2 3 4 5 Grant's 531, 532, 534 Netter's 421, 431 Rohen 418, 432 6 7 8 9 10 11 3 Grant's 513, 516, 517 Netter's 174, 177, 424–427, 477 Rohen 382, 383 S1 2 3 FIGURE 4-2 Cutaneous nerves of the back (posterior primary rami). of the spine as far as its medial end. Using your finger, separate the trapezius from underlying structures. Cut those fibers attached to the clavicle and reflect the trapezius medially to uncover the underlying supraspinatus muscle (see ATLAS PLATE 60). Observe that the deltoid muscle attaches above to a bony arch formed by the clavicle anteriorly, the acromion laterally, and the spine of the B. Subacromial Bursa. Deep to the deltoid muscle, identify the large subacromial bursa (ATLAS PLATES 32, 119.2). Open it and, with your finger, explore its extensive sac. Note that it extends beneath the deltoid muscle (but superficial to the joint capsule) and is continued under the acromion and the coracoacromial ligament, superficial to the tendon of the supraspinatus (ATLAS PLATES 119.2, 114.1). When the bursa is inflamed, 90º abduction of the arm at the shoulder joint (using the supraspinatus and deltoid muscles) is painful because the entire bursa moves under the acromion. 12 L1 2 25 C. Supraspinatus Fossa; Suprascapular Vessels and Nerve. Remove the deep fascia overlying the supraspinatus muscle. Observe that it arises in the supraspinatus fossa, courses deep to the acromion, and inserts on the uppermost part of the greater tubercle of the humerus (Figure 4-4). Palpate the superior border of the scapula and locate the sharp edge of the superior transverse scapular ligament (ATLAS PLATE 114.2) where the suprascapular nerve and vessels pass into the supraspinatus fossa (Figure 4-4). Make a vertical cut across the supraspinatus muscle medial to the ligament, approximately 11⁄2 inches lateral to the vertebral border of the scapula. Reflect the lateral part of the muscle toward the humerus and note that the suprascapular nerve usually enters the fossa deep to the ligament and the suprascapular vessels pass superficial to the ligament (ATLAS PLATE 33.1 and Figure 4-4). D. Infraspinatus Fossa. Remove the deep fascia covering the infraspinatus muscle below the spine of the scapula. Observe that most of its fibers arise from the medial two-thirds of the infraspinatus fossa. From this origin, the muscle ascends over the fibrous capsule of the shoulder joint and terminates on LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 26 Aptara Inc 26 DISSECTION 4 Rhomboid minor muscle Levator scapulae muscle Supraspinatus muscle Spine of scapula Infraspinatus muscle Rhomboid major muscle Greater tubercle (humerus) Teres minor muscle Vertebral border of scapula Teres major muscle FIGURE 4-3 the greater tubercle of the humerus below the supraspinatus muscle (ATLAS PLATES 58, 456). Cut through the infraspinatus muscle vertically with a scalpel 2 inches lateral to the vertebral border of the scapula; reflect the lateral part of the muscle toward the humerus (ATLAS PLATE 33). The scapular muscles, posterior view. Grant's 513, 517, 528 Netter's 174, 177, 424–427, 477 Rohen 382, 383, 403–405 Observe the suprascapular nerve and vessels passing into the infraspinatus fossa to supply this muscle by coursing through the spinoglenoid notch (greater scapular notch), located lateral to the free edge of the scapular spine (Figure 4-4). At times, a bursa is found between the infraspinatus tendon of the muscle and the capsule of the shoulder joint. LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 27 Aptara Inc Scapular and Deltoid Regions; Posterior Compartment of the Arm 27 Supraspinatus muscle (reflected) Suprascapular artery Transverse scapular ligament Spine of scapula Infraspinatus muscle (reflected) Suprascapular nerve Teres minor muscle Supraspinous fossa Spinoglenoid notch Triceps brachii muscle (long head) Infraspinous fossa Teres major muscle FIGURE 4-4 The suprascapular nerve and artery (posterior scapular view). III. Lateral Border of Scapula; Triangular and Quadrangular Spaces; Axillary Nerve and Deltoid Region lateral border of the scapula (ATLAS PLATE 65). Follow the teres minor muscle laterally and observe its insertion on the lower part of the greater tubercle of the humerus below the infraspinatus. The sharp lateral border of the scapula is thickly covered with muscles. These include the latissimus dorsi at the inferior angle and then the teres major, teres minor, and the long head of the triceps brachii attaching to the infraglenoid tubercle (ATLAS PLATES 32, 60, 65). A. Lateral Border of the Scapula (Figure 4-3). Clearly define the inferior border of the infraspinatus muscle and separate it from the teres minor muscle, which arises along the middle third of the Grant's 517, 526–528 Netter's 177, 424–427, 432, 477 Rohen 226, 382, 383, 403 Find the teres major muscle, which arises from the lower one-third of the lateral border, as far as the inferior angle (ATLAS PLATE 65). Its fibers can be distinguished from those of the teres minor because they form a flat tendon (approximately 2 inches long) that courses to the anterior aspect of the humerus. The teres major muscle inserts along the medial lip of the intertubercular sulcus. At its insertion, the teres major tendon lies just behind that of the latissimus dorsi muscle (ATLAS PLATE 64). LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 28 Aptara Inc 28 DISSECTION 4 cumflex scapular branch of the subscapular artery that courses around the lateral border of the scapula and through the space from the axilla (ATLAS PLATE 33.1). Identify the long head of the triceps brachii muscle and observe its origin from the infraglenoid tubercle of the scapula (ATLAS PLATES 60, 63, 65). Follow the muscle inferiorly, and note that it passes between the teres major and minor muscles on the humerus. As the long head of the triceps brachii muscle descends from the infraglenoid tubercle to the extensor aspect of the arm, it crosses a three-sided area bounded above by the lower border of the teres minor, below by the upper border of the teres major, and laterally by the surgical neck of the humerus. Two spaces are thereby formed from the three-sided area, one medial to the long head of the triceps, called the triangular space, and one lateral to the muscle, called the quadrangular space (ATLAS PLATES 32, 60). B. Triangular and Quadrangular Spaces (Figure 4-5). Find the long head of the triceps. Clean the lateral and medial borders of the muscle and identify the triangular space bounded laterally by the long head of the triceps, superiorly by the teres minor muscle, and inferiorly by the teres major muscle (ATLAS PLATE 60). Find the cir- Similarly, identify the quadrangular space located lateral to the long head of the triceps muscle. Observe that it is bounded superiorly by the teres minor muscle, inferiorly by the teres major muscle, laterally by the neck of the humerus, and medially by the long head of the triceps. Probe for the posterior humeral circumflex artery and axillary nerve that pass through the quadrangular space from the axilla (ATLAS PLATE 67). Grant's 484, 510, 527, 528 Netter's 426, 477, 481 Rohen 400, 405, 409 Grant's 527, 528 Netter's 426, 427 Rohen 408, 409 C. Axillary Nerve. Because the scapular origin of the deltoid muscle has already been detached, the muscle can be turned forward to demonstrate the axillary nerve that enters its deep surface (ATLAS PLATE 67). On its course through the quadrangular space, the axillary nerve gives sensory branches to the shoulder joint and supplies the teres minor muscle and the posterior part of the deltoid (ATLAS PLATE 67). This branch then becomes superficial over the deltoid muscle as the upper lateral Deltoid muscle Upper lateral brachial cutaneous nerve (from axillary) Axillary nerve (in quadrangular space) Posterior humeral circumflex artery Infraspinatus muscle Teres minor muscle Triceps muscle (long head) Teres major muscle FIGURE 4-5 Circumflex scapular artery (in triangular space) The quadrangular and triangular spaces (posterior view). LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 29 Aptara Inc Scapular and Deltoid Regions; Posterior Compartment of the Arm brachial cutaneous nerve (ATLAS PLATE 37). Another large branch continues around the humerus with the posterior humeral circumflex artery to supply parts of the deltoid attaching to the acromion and the clavicle. Four structures are supplied by the axillary nerve: two muscles with motor innervation, the teres minor and deltoid; and two regions with sensory innervation, the shoulder joint and the cutaneous area covering the shoulder joint and deltoid. Clinical Relevance Axillary nerve injury. The axillary nerve branches from the posterior cord of the brachial plexus and traverses the quadrangular space to reach the posterolateral aspect of the shoulder. At this site it can be injured when the humeral head is dislocated or the surgical neck of the humerus is fractured, because that part of the humerus forms the lateral boundary of the quadrangular space. Resulting from this nerve lesion is the loss of innervation to the deltoid and teres minor mus- Thyrocervical trunk 29 cles and a loss of sensory supply to the skin over the shoulder joint and, to some extent, the shoulder joint itself. Denervation of the deltoid muscle causes a loss of the smooth contour of the shoulder and a weakness or inability to abduct the upper limb beyond the first 20° still be performed by the intact supraspinatus muscle. IV. Anastomoses Around the Scapula The blood vessels in the scapular region participate in anastomoses that allow blood to reach the remainder of the upper limb should blockage occur between the first and third parts of the subclavian artery. The transverse cervical artery (with its descending branch coursing down the vertebral border of the scapula) and the suprascapular artery (which enters both the supraspinatus and infraspinatus fossae) both arise as branches off the thyrocervical trunk from the 1st part of the subclavian artery. These anastomose freely with the circumflex scapular branch of the subscapular artery and the posterior humeral circumflex artery, which arise from the 3rd part of the axillary artery (Figure 4-6). Transverse cervical artery Suprascapular artery Axillary artery Subclavian artery Supraspinatus muscle Infraspinatus muscle Teres minor muscle Anterior and posterior humeral circumflex arteries Descending branch of transverse cervical artery Circumflex scapular artery Brachial artery Teres major muscle FIGURE 4-6 The scapular anastomosis on the posterior aspect of the shoulder. Note the descending branch of the transverse cervical artery, the suprascapular artery, circumflex scapular artery, and the two humeral circumflex arteries. LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 30 Aptara Inc 30 DISSECTION 4 A B FIGURE 4-7 Skin incisions of arm and forearm. V. Posterior (Extensor) Compartment of the Arm The posterior compartment of the arm contains one large muscle with three heads—the triceps brachii muscle— and the important radial nerve with its accompanying profunda brachii artery (ATLAS PLATES 62, 63, 67, 68). The principal function of the triceps is to extend the forearm at the elbow joint. However, because its long head arises from the infraglenoid tuberosity, the triceps also can extend the humerus at the shoulder joint. Clinical Relevance Suprascapular nerve injury. The suprascapular nerve runs laterally from the superior trunk of the brachial plexus and then courses deep to the suprascapular ligament that overlies the suprascapular notch. It then enters the supraspinatus fossa where it supplies the supraspinatus muscle. Trauma to this nerve can occur in persons who have jobs that require carrying heavy objects, such as steel rods, or persons that ascend ladders with a V-shaped wooden container full of bricks (hod carrier). They begin to feel that something is wrong with their arm and, when told by their doctor to lift their upper limb, they bend the upper part of their body toward the side, gaining the first 20° of abduction of their arm, after which they easily raise their arm because the deltoid is intact. These patients are unable to initiate the first 20° of abduction because the supraspinatus muscle is denervated because of trauma to the suprascapular nerve. Supraclavicular nerves (C3, C4) Intercostobrachial nerve (T2) Upper lateral brachial cutaneous nerve (axillary) FIGURE 4-8 Posterior brachial cutaneous nerve (radial) Medial cutaneous nerve of forearm (medial cord) Lower lateral brachial cutaneous nerve (radial) Posterior cutaneous nerve of forearm (radial) Cutaneous nerves of the arm (posterior view). LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 31 Aptara Inc Scapular and Deltoid Regions; Posterior Compartment of the Arm A. Superficial Nerves. From the circular incision through the skin around the upper part of the arm (Figure 4-7), incise the skin downward along the anterior surface of the arm and forearm to the wrist. Make another circular incision at the wrist (Figure 4-7 A, B). Grant's 483, 484 Netter's 479, 480 Rohen 400–408 Dissect the superficial fascia of the arm and find the upper lateral brachial cutaneous nerve from the axillary nerve over the deltoid muscle (described earlier). Find the lower lateral brachial cutaneous nerve (a branch of the radial nerve). It passes through the triceps muscle to become superficial just below the insertion of the deltoid muscle (Figure 4-8). More medially, find the intercostobrachial nerve (T2) extending through the 2nd intercostal space to supply the medial and posterior part of the arm (ATLAS PLATE 36). B. Triceps Brachii Muscle. Remove the fascia completely and clean the three heads of the triceps. Trace the long head down from the scapula and follow it to the lateral head (Figure 4-9), which arises from the upper, posterior surface of the humerus above the spiral groove. Identify the medial head of the triceps arising from the posterior surface of the humerus below the insertion of the teres major muscle and just distal to the spiral groove (ATLAS PLATE 63). Infraglenoid tubercle of scapula Follow the main trunk of the radial nerve through the lateral intermuscular septum. Note that medially the brachialis muscle is found, and laterally the nerve is bounded by the brachioradi- Triceps brachii muscle Long head Lateral head Medial head Grant's 524–528, 542, 544, 600 Netter's 424, 432, 477 Rohen 382, 387 Triceps tendon Medial epicondyle Observe that the triceps tendon of insertion forms near the middle of the arm and inserts on the upper posterior part of the olecranon of the ulna (ATLAS PLATES 62, 67). Identify the small triangular anconeus muscle on the dorsal aspect of the elbow (ATLAS PLATES 63, 66). C. Radial Nerve and Profunda Brachii Vessels (Figure 4-10). With the forearm extended, insert a probe deep to the lateral head of the triceps approximately 1 inch above its insertion (in the same direction as the spiral groove). Being certain that you do not sever the radial nerve and the profunda brachii artery, cut completely through the lateral head of the triceps and reflect its two ends (ATLAS PLATE 67). This will expose the radial nerve and its accompanying vessels within the spiral groove (see cross section (ATLAS PLATE 132.1). Appreciate the vulnerability of these structures if the upper part of the shaft of the humerus is fractured. 31 Lateral epicondyle Olecranon process of ulna Ulna FIGURE 4-9 Head, radius Radius The triceps muscle. alis muscle and the extensor carpi radialis longus. Follow the nerve to the lateral epicondyle where it divides into superficial and deep branches, both of which enter the forearm. Grant's 481, 488, 504, 510 Netter's 432, 434, 477 Rohen 399, 408, 409 In addition to the small cutaneous branches from the radial nerve that supply the posterior region of the arm, the larger posterior cutaneous nerve of the forearm is also derived from the radial nerve (Figure 4-8 and ATLAS PLATE 37). This nerve traverses the lateral head of the triceps to become superficial 2 inches above the elbow. It then descends behind the lateral epicondyle to supply the skin on the dorsum of the forearm as far as the wrist (ATLAS PLATE 69). LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 32 Aptara Inc 32 DISSECTION 4 Deltoid muscle Long head of triceps Biceps brachii muscle Radial nerve Lateral head of triceps Deep brachial artery Brachialis muscle Deep branch of radial nerve Middle collateral branch (of deep brachial artery) Radial collateral branch (of deep brachial artery) Triceps brachii muscle FIGURE 4-10 The radial nerve and profunda (deep) radial artery in the lateral brachial region. Superficial branch of radial nerve Brachioradialis muscle Lateral epicondyle Extensor carpi radialis longus muscle Find the profunda, or deep brachial artery, coursing with the radial nerve in the spiral groove (ATLAS PLATE 44). It branches from the brachial artery and courses laterally and posteriorly to join the nerve. Note that the vessel terminates by dividing into the middle and radial collateral branches (ATLAS PLATE 44). These branches participate in the anastomosis around the lateral aspect of the elbow joint (ATLAS PLATE 44). The middle collateral branch anastomoses with the interosseous recurrent artery (from the common interosseous artery), whereas the radial collateral branch anastomoses with the radial recurrent artery (from the radial artery) (ATLAS PLATE 79.1). Grant's 486, 487 Netter's 434 Rohen 397 Clinical Relevance Rotator cuff. This musculotendinous structure reinforces the capsule of the shoulder joint. It tends to retain the head of the humerus within the glenoid fossa. The cuff consists of the tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis muscles. Tears in the rotator cuff frequently occur when dislocation of the humeral head occurs. The tendons reinforce the anterior, posterior, and superior aspects of the joint capsule, but not the inferior part. Consequently, these dislocations are most often inferior and medial to the joint. Rotator cuff injury frequently occurs in curveball pitchers when strong rotation of the upper limb is required to throw the ball. LWBK529-C04_023-033.qxd 3/8/10 10:12PM Page 33 Aptara Inc Scapular and Deltoid Regions; Posterior Compartment of the Arm Radial nerve injury. The course of the radial nerve (accompanied by the deep brachial artery) around the shaft of the humerus places the nerve vulnerable to injury or to severance in fractures of the humerus. The nerve can also be injured more proximally in the axilla by excessive pressure from the inept use of crutches or by the so-called "Saturday night palsy" when the arm or armpit of a drunken person is draped over a hard surface (such as the back of a chair) and the person falls asleep. Additionally, the nerve can be injured by an inferomedial dislocation of 33 the humeral head. The resultant injury in the axilla paralyzes the triceps muscle and the posterior forearm muscles so that the person is unable to extend the forearm at the elbow joint, the hand at the wrist, and the fingers. "Wrist drop" (flexion of the hand) occurs because the flexor muscles of the forearm act unopposed. The flexed hand also reduces the strength of flexion of the fingers. Radial nerve lesions may result in some sensory loss along the middle of the posterior surface of the forearm and the lateral aspect of the dorsal hand. LWBK529-C05_034-045.qxd 3/9/10 1:12 PM Page 34 Aptara DISSECTION 5 Anterior Brachial Region; Cubital Fossa; Anterior Forearm and Wrist Objectives 1 Learn the surface anatomy and bony features of the arm and forearm. 2 Dissect the basilic vein and cutaneous nerves of the anterior arm and forearm. 4 Dissect the structures in the cubital fossa. 5 Dissect the anterior compartment of the forearm. 6 Identify the tendons, vessels, and nerves at the anterior wrist. 3 Dissect the anterior compartment of the arm. ATLAS KEY: rounded contour of the shoulder below the acromion (ATLAS PLATE 115). It moves with the humerus when t