Question

Answer the following question in detail.

Justify the structure of atlas and axis vertebrae with respect to their position and function.

Answer 1

• Atlas vertebrae:

1. Atlas is the ring-like, 1^st cervical vertebrae. It has anterior, posterior arches and large lateral masses.
2. It lacks centrum and spinous process. The superior surfaces of the lateral masses are concave and are known as superior articular facets.
3. These facets articulate with the occipital condyles of the occipital bone thereby forming atlanto-occipital joints. This articulation permits ‘YES movement’ or nodding movement.
4. The inferior surfaces of the lateral masses known as inferior articular facets articulate with axis vertebrae.

• Axis vertebrae:

1. It is the 2^nd cervical vertebrae.
2. A peg-like process called odontoid process projects superiorly through the anterior portion of the vertebral foramen of the atlas.
3. The odontoid process forms a pivot on which the atlas and head rotate. This arrangement allows ‘NO movement’ or side to side movement of the head.
4. The articulation formed between the anterior arch of the atlas, the odontoid process of the axis, and between their articular facets is called the atlanto-axial joint.