The trapezius[4] is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports the arm.

The trapezius muscle (plural: trapezei) is a surface muscle of back, shown in red above and below
Trapezius Gray409.PNG
OriginMedial one-third of superior nuchal line, external occipital protuberance, spinous processes of vertebrae C7-T12, Nuchal ligament[1]
Insertionposterior border of the lateral one-third of the clavicle, acromion process, and spine of scapula
Arterysuperficial branch of transverse cervical artery or superficial cervical artery [2]
Nerveaccessory nerve (motor)
cervical spinal nerves C3 and C4 (motor and sensation)[3]
ActionsRotation, retraction, elevation, and depression of scapula
Antagonistserratus anterior muscle, Latissimus dorsi, Pectoralis Major
LatinMusculus trapezius
Anatomical terms of muscle


Name and historyEdit

The trapezius muscle resembles a trapezium (trapezoid in American English), or diamond-shaped quadrilateral. The word "spinotrapezius" refers to the human trapezius, although it is not commonly used in modern texts. In other mammals, it refers to a portion of the analogous muscle. Similarly, the term "tri-axle back plate" was historically used to describe the trapezius muscle.[citation needed]


Position of trapezius and its parts.
  Superior fibers of the trapezius
  Middle fibers of the trapezius
  Inferior fibers of the trapezius

The superior or upper (or descending) fibers of the trapezius originate from the spinous process of C7, the external occipital protuberance, the medial third of the superior nuchal line of the occipital bone (both in the back of the head), and the ligamentum nuchae. From this origin they proceed downward and laterally to be inserted into the posterior border of the lateral third of the clavicle.







Motor function is supplied by the accessory nerve.[5] Sensation, including pain and the sense of joint position (proprioception), travel via the ventral rami of the third (C3) and fourth (C4) cervical spinal nerves.[5] Since it is a muscle of the upper limb, the trapezius is not innervated by dorsal rami, despite being placed superficially in the back.


Contraction of the trapezius muscle can have two effects: movement of the scapulae when the spinal origins are stable, and movement of the spine when the scapulae are stable.[5] Its main function is to stabilize and move the scapula.[5]

Scapular movementsEdit

The upper fibers elevate the scapulae, the middle fibers retract the scapulae, and the lower fibers depress the scapulae.[5]

In addition to scapular translation, the trapezius induces scapular rotation. The upper and lower fibers tend to rotate the scapula around the sternoclavicular articulation so that the acromion and inferior angles move up and the medial border moves down (upward rotation). The upper and lower fibers work in tandem with serratus anterior to upwardly rotate the scapulae, and work in opposition to the levator scapulae and the rhomboids, which effect downward rotation.

An example of trapezius function is an overhead press. When activating together, the upper and lower fibers also assist the middle fibers (along with other muscles such as the rhomboids) with scapular retraction/adduction.

The trapezius also assists in abduction of the shoulder above 90 degrees by rotating the glenoid upward. Injury to cranial nerve XI will cause weakness in abducting the shoulder above 90 degrees.

Spinal movementsEdit

When the scapulae are stable, a co-contraction of both sides can extend the neck.

Clinical significanceEdit

Dysfunction of the trapezius can result in winged scapula, sometimes further specified as "lateral winging"[6] and in an abnormal mobility or function of the scapula (scapular dyskinesia).[7] There are multiple causes of trapezius dysfunction.


Trapezius palsy, due to damage of the spinal accessory nerve, is characterized by difficulty with arm adduction and abduction, and associated with a drooping shoulder, and shoulder and neck pain.[8] Intractable trapezius palsy can be surgically managed with an Eden-Lange procedure.

Facioscapulohumeral muscular dystrophyEdit

The trapezius muscle is one of the commonly affected muscles in facioscapulohumeral muscular dystrophy (FSHD). The lower and middle fibers are affected initially, and the upper fibers are commonly spared until late in the disease.[9]


Although rare, underdevelopment or absence of the trapezius has been reported to correlate to neck pain and poor scapular control that are not responsive to physical therapy.[10] Absence of the trapezius has been reported in association with Poland syndrome.[11]

Society and cultureEdit


  • The upper portion of the trapezius can be developed by elevating the shoulders. Common exercises for this movement are any version of the clean, particularly the hang clean, and the shoulder shrug.
  • Middle fibers are developed by pulling shoulder blades together. This adduction also uses the upper/lower fibers. The uppermost area can be trained through neck extension.

It is mainly used in throwing, with the deltoid muscle and rotator cuff.


  1. ^ Rockwood, Charles A. (January 1, 2009). The Shoulder. ISBN 978-1416034278.
  2. ^ "Tufts". Archived from the original on April 22, 2003. Retrieved December 11, 2007.
  4. ^ Lajtai, Georg; Applegate, Gregory; Snyder, Stephen J.; Aitzetmüller, Gernot; Gerber, Christian (March 11, 2003). "trapezoid"&pg=PA89 Shoulder Arthroscopy and MRI Techniques: 20 Tables. ISBN 9783540431121.
  5. ^ a b c d e Bakkum, Barclay W.; Cramer, Gregory D. (January 1, 2014), Cramer, Gregory D.; Darby, Susan A. (eds.), "Chapter 4 - Muscles That Influence the Spine", Clinical Anatomy of the Spine, Spinal Cord, and Ans (Third Edition), Saint Louis: Mosby, pp. 98–134, ISBN 978-0-323-07954-9, retrieved January 8, 2021
  6. ^ Martin, RM; Fish, DE (March 2008). "Scapular winging: anatomical review, diagnosis, and treatments". Current Reviews in Musculoskeletal Medicine. 1 (1): 1–11. doi:10.1007/s12178-007-9000-5. PMC 2684151. PMID 19468892.
  7. ^ Panagiotopoulos AC, Crowther IM (2019). "Scapular Dyskinesia, the forgotten culprit of shoulder pain and how to rehabilitate". SICOT-J. 5: 29. doi:10.1051/sicotj/2019029. PMC 6701878. PMID 31430250.
  8. ^ Wiater JM, Bigliani LU (1999). "Spinal accessory nerve injury". Clinical Orthopaedics & Related Research. 368 (1): 5–16. doi:10.1097/00003086-199911000-00003
  9. ^ "Evaluation and Management of Scapular Winging due to Facioscapulohumeral dystrophy (FSH)". Cancer Therapy Advisor. January 17, 2019.
  10. ^ Bergin, Michael; Elliott, James; Jull, Gwendolen (2011). "The Case of the Missing Lower Trapezius Muscle". Journal of Orthopaedic & Sports Physical Therapy. 41 (8): 614. doi:10.2519/jospt.2011.0416. PMID 21808102.
  11. ^ Yiyit, N; Işıtmangil, T; Oztürker, C (November 2014). "The abnormalities of trapezius muscle might be a component of Poland's syndrome". Medical Hypotheses. 83 (5): 533–6. doi:10.1016/j.mehy.2014.09.007. PMID 25257706.

External linksEdit

  This article incorporates text in the public domain from page 432 of the 20th edition of Gray's Anatomy (1918)