Vertebral (spinal)column

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Bone classifications

Hospital Corpsman Revised Edition

Thoracic

VERTEBRAL (SPINAL) COLUMN.-The vertebral column consists of 24 movable or true vertebrae; the sacrum; and the coccyx, or tail bone (fig. 1-17). The vertebrae protect the spinal cord and the nerves that branch out from the spinal cord. Each vertebra has an anterior portion, called the body, which is the large solid segment of the bone (fig. 1-18). This vertebral body supports not only the spinal cord but other structures of the body as well. At the bottom of the spinal column is the sacrum and the coccyx. Many of the main muscles are attached to the vertebrae.
The vertebral foramen is a hole directly behind the body of the vertebrae that forms the passage for the spinal cord. The vertebral projections are for the attachments of muscles and ligaments and for facilitating movement of one vertebra over another. The spinal column is divided into five regions in the following order: cervical (neck), thoracic (chest),

Figure 1-16.-Facial bones.

lumbar (lower back), and sacral and coccygeal (pelvis).

Cervical.-There are seven cervical vertebrae in the neck. The first is called the atlas and resembles a bony ring. It supports the head. The second is the highly specialized axis. It has a bony prominence that fits into the ring of the atlas, thus permitting the head to rotate from side to side. The atlas and the axis are the only named vertebrae; all others are numbered. See figure 1-19. Each cervical vertebra has a transverse (or intervertebral) foramen (fig. 1-19) to allow passage of nerves, the vertebral artery, and a vein. The seventh cervical vertebra has a prominent projection that can easily be felt at the nape of the neck. This landmark makes it possible for physicians to count and identify the vertebrae above and below it.