The axis is the second cervical vertebra, commonly called C2. It is an atypical cervical vertebra with unique features and important relations that make it easily recognisable. Its most prominent feature is the odontoid process (also know as the dens or peg), which is embryologically the body of the atlas (C1) 1,2 .

The spinous process forms from the merger of the two laminae of axis. It is large, and usually contains a broad base and a bifid tip. The spinous process projects almost 1 cm further posteriorly than the posterior tubercle of atlas and covers the spinous process of the third cervical vertebra (C3).

The Axis (C2 vertebra) also known as epistropheus forms the pivot upon which the first cervical vertebra (the Atlas), which carries the head, rotates. The axis is composed of a vertebral body, heavy pedicles, laminae, and transverse processes, which serve as attachment points for muscles.

2. Spinous Process. There is yet another narrow projection at the back of the axis from the point where the two laminae meet. It is called the spinous process. It provides a point for attachment for several muscles and ligaments that help move the head.

C3-C7 are more classic vertebrae, having a body, pedicles, laminae, spinous processes, and facet joints. C1 and C2 form a unique set of articulations that provide a great degree of mobility for the skull. C1 serves as a ring or washer that the skull rests upon and articulates in a pivot joint with the dens or odontoid process of C2.