Describe the various parts/components of the axial skeletal system with a diagram.

(N/A) The axial skeleton comprises $80$ bones distributed along the main axis of the body.
- The skull,vertebral column,sternum,and ribs constitute the axial skeleton.
$(a)$ Skull: It is composed of two sets of bones - cranial and facial,totaling $22$ bones.
- Cranium: There are $8$ cranial bones. They form the hard,protective outer covering for the brain.
The bones forming the cranium are: $1$ Frontal,$2$ Parietal,$2$ Temporal,$1$ Occipital,$1$ Sphenoid,$1$ Ethmoid. Total = $8$.
Cranial bones are joined with each other by wavy,immovable joints called sutures.
- The facial region is made up of $14$ skeletal elements: $2$ Nasal,$2$ Maxillae,$2$ Palatine,$2$ Zygomatic,$2$ Lacrimal,$2$ Conchae,$1$ Vomer,$1$ Mandible. Total = $14$.
- $A$ single $U$-shaped bone called the hyoid is present at the base of the buccal cavity.
- Each middle ear contains three tiny bones - Malleus,Incus,and Stapes,collectively called ear ossicles.
The skull region articulates with the superior region of the vertebral column with the help of two occipital condyles (the skull is called dicondylic).
$(b)$ Vertebral column: It is formed by $26$ serially arranged units called vertebrae and is dorsally placed. It extends from the base of the skull and constitutes the main framework of the trunk.
- Each vertebra has a central hollow portion called the neural canal through which the spinal cord passes.
- The vertebral column consists of: $(1)$ Cervical vertebrae $(7)$,$(2)$ Thoracic vertebrae $(12)$,$(3)$ Lumbar vertebrae $(5)$,$(4)$ Sacral vertebrae ($1$ fused),$(5)$ Coccygeal vertebrae ($1$ fused). Total = $26$.
Function: It protects the spinal cord,supports the head,and serves as the point of attachment for the ribs and musculature of the back.
$(c)$ Sternum: It is a flat bone on the ventral midline of the thorax.
$(d)$ Ribs: There are $12$ pairs of ribs. Each rib is a thin,flat bone connected dorsally to the vertebral column and ventrally to the sternum. It has two articulation surfaces on its dorsal end and is hence called bicephalic.
- True ribs: The first $7$ pairs are attached dorsally to the thoracic vertebrae and ventrally to the sternum with the help of hyaline cartilage.
- False ribs: The $8^{th}, 9^{th}$,and $10^{th}$ pairs do not articulate directly with the sternum but join the $7^{th}$ rib with the help of hyaline cartilage. They are called vertebrochondrial ribs.
- Floating ribs: The $11^{th}$ and $12^{th}$ pairs are not connected ventrally.
Thoracic vertebrae,ribs,and sternum together form the rib cage,which protects the lungs,heart,and large blood vessels.