The axial skeleton is composed of the skull, mandible, hyoid, ribs and vertebrae.

Begin your exploration of the axial skeleton by clicking on the skull.

Click to examine a typical vertebra. Vertebrae all have a body or centrum located on the ventral surface of the bone. The size of the centrum varies along the length of the vertebral column. Vertebrae also have an arch that creates a large opening through which the spinal cord passes.

Vertebrae have three types of processes: a dorsal spinous process, lateral transverse processes, and anterior and posterior articular processes. The articular processes orient dorsally on the anterior surface of a vertebra and ventrally on the posterior surface. Muscles that control the movement of the vertebral column attach to these processes. Pay special attention to how the processes change along the length of the vertebral column. Also note the manner in which the vertebrae overlap.

Click on a region of the axial skeleton above for a close up view of the different types of vertebrae that compose the vertebral column. Click on numbers to identify structures.

Cervical vertebrae have small transverse processes containing a hole through which nerves and blood vessels pass.

Thoracic vertebrae are associated with the ribs. They can be identified by the presence of articular surfaces for rib attachment.

Lumbar vertebrae have flattened, enlarged, anteriorly oriented transverse processes. These are surfaces to which muscles that control movement of the vertebral column attach.

Sacral vertebrae are fused to provide support for the pelvic girdle.

Caudal vertebrae provide structure for the tail and differ in number depending on tail length.

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