Question

Human vertebral formula is-
a. $C_{4}T_{8}L_{4}S_{8}Co_{8}$
b. $C_{7}T_{8}L_{5}S_{6}Co_{7}$
c. $C_{7}T_{12}L_{5}S_{4}Co_{5}$
d. $C_{7}T_{12}L_{5}S_{5}Co_{4}$

Answer 1

Hint: The vertebral formula is a formula that describes the number of vertebrae in each segment of the vertebral column. It is also called the backbone or spinal column and is a part of the axial skeleton.

Complete answer:
The vertebral column or spinal column is the central axis of the skeleton that is found in all vertebrates and the formula that refers to the number of vertebrae present in each segment of the vertebral column is called the vertebral formula.

The vertebral column is the main feature of a vertebrate. The notochord is a flexible type rod of uniform composition that is found in all chordates. In the vertebral column, the notochord is replaced by vertebrae which is a segmented series of bones. Vertebrae are separated by intervertebral discs.

The main function of the vertebral column is to provide attachments to muscles, support the trunk, protect the spinal cord and nerve roots, and serves as a site for hematopoiesis.

The vertebral column in humans is generally formed by 33 vertebrae. These vertebrae are arranged in series and connected by ligaments and intervertebral discs. In some cases, the number of vertebrae can vary between 32 and 35.

The vertebrae in the human vertebral column are divided into different regions and each region corresponds to the curves of the spinal column. Vertebrae in these regions are usually the same but with little variation. The cervical spine, thoracic spine, lumbar spine, sacrum, and coccyx are the important regions. These vertebrae are named based on their region of the spine. In the case of mammals, the vertebral column made up of five morphologically differentiated groups of vertebrae base on their region and position, they are
- Cervical - found in the cervical spine region,
- Thoracic - found in the thoracic spine region,
- Lumbar - found in lumbar spine region,
- Sacral - found in the sacrum region, and
- Coccygeal - found in the coccyx region.
The upper twenty-four vertebrae are articulating and disconnected from each other by intervertebral discs. Only these are moveable. In adults, the lower nine are fused. Five in the sacrum, and four in the coccyx or tailbone are present.

In human, the number of various vertebrae is as follows:
- Cervical – 7
- Thoracic – 12
- Lumbar – 5
- Sacral – 5
- Coccygeal – 4
C, T, L, S, and Co denote cervical, thoracic, lumbar, sacral, and coccygeal vertebrae respectively.

Hence, the correct answer is option (D).

Note: The vertebral formula denotes the number of vertebrae in each segment of the vertebral column which is a part of the central axis of the skeleton. According to the region of the vertebral column, in humans, there are 5 types of vertebrae. They are cervical, thoracic, lumbar, sacral, coccygeal and their number is 7, 12, 5, 5, and 4 respectively.