Question

Explain axial skeleton.

Answer 1

Axial skeleton: This consists of skull, vertebral column, sternum and ribs. Human skull has 22 bones of which 8 are present in the cranium and 14 on the face. Brain is present in the cavity called cranium. In the occipital region is an opening called foramen magnum through which spinal cord passes. Cranium has 8 bones which covers the brain from all sides.
(1) Facial bones: These bones form the face and protect the sensory organs present in the head. It has 14 bones.
(2) Vertebral Column: It makes the axis of the body and provides support like a pillar. Vertebral column is divided into following five parts:
(a) Cervical Region. It has 7 cervical vertebrae. First vertebra is called atlas, second is axis and rest are called typical cervical vertebrae.
(b) Thoracic Region. It has 12 thoracic vertebrae. Neural spine of these vertebrae is long and pointed, which provdes surface for muscle and attachment.
(c) Lumber Region. It has 5 lumber vertebrae.
(d) Sacral Region. It has 5 sacral vertebrae which are permanently fused to each other. These are situated on both halves of pelvic and form a joint with pelvic girdle.
(e) Caudal Region. It has 4 caudal vertebrae. These are also fused to form a triangular structure which is called coccyx.
(3) Sternum and Ribs: Sternum is the bone at the mid-ventral line of the thorax to which most of the ribs are attached at their ventral ends. Ribs are formed by vertebral and sterna part. First seven pairs of ribs are called true ribs. These are joined on one side with sternum and on second side with thorax.