CBSE Class 9 Answered

Cervical vertebrae

The seven bones in the cervical region are generally small and delicate. Numbered top-to-bottom from C1-C7, atlas (C1) and axis (C2), are the vertebrae that allow the neck and head so much movement. The axis also sits upon the first intervertebral disk of the spinal column. The transverse processes of the cervical vertebrae are distinctive because they have "transverse foramina", which serve as passageways for arteries leading to the brain. Also, the "spinous processes" of the second through the fifth cervical vertebrae are uniquely forked. These processes provide attachments for various muscles.

Thoracic vertebrae

The twelve (12) thoracic bones and their transverse processes have surfaces that articulate with the ribs. Some rotation can occur between the thoracic vertebrae, but their connection with the rib cage prevents much flexion . They may also be known as 'dorsal vertebrae', in the human context.

.

Lumbar vertebrae

These five vertebrae are very robust in construction, as they must support more weight than other vertebrae. They allow significant flexion and extension and a small degree of rotation. The discs between these vertebrae create a lumbar lordosis (curvature that is concave posteriorly) in the human spine.

Sacral vertebrae

There are five (vertebrae (S1-S5) and they are fused in maturity, with no intervertebral discs.

 Coccygeal vertebrae

There are usually four (4) and rarely 3-5 vertebrae (Co1-Co5), with no intervertebral discs. Many animals have a greater number of "tail vertebrae" and, in animals, they are more commonly known as "caudal vertebrae."