The costal pleura is innervated by the intercostal nerves. The cut overlies the sternum, ribs, and connecting costal cartilages. Without the rib cages, costal cartilages, and intercostal muscles, the lungs would collapse. The trachea of the costal vein is perhaps a branch of the subcostal trachea. It is located between the costal margins and the subcostal plane. Pectus carinatum is an overgrowth of costal cartilage causing the sternum to protrude forward. The carapace has five pairs of costal scutes. The plant grows among costal dunes and sandy environments. Other cells move distally to the costal processes of thoracic vertebrae to form the ribs. A cervical rib represents a persistent ossification of the C7 lateral costal element. The articular surface extends to the inferior aspect for attachment with the first costal cartilage. This Greek word means literally "below the cartilage" which refers to the costal cartilages. At the front, fibres insert into the xiphoid process and along the costal margin. These articulate with the superior and inferior costal facets on the connecting vertebrae. Each rib has a depression shaped like a cup that the costal cartilage articulates with.