PREVIOUSLY ASKED IN:
PSC Miscellaneous Prelims 2018
Answer
31 pairs
Explanation
In the human peripheral nervous system, there are two main types of nerves: cranial nerves and spinal nerves. There are exactly 31 pairs of spinal nerves (62 nerves in total) that emerge from segments of the spinal cord and branch out to various parts of the body. In contrast, there are 12 pairs of cranial nerves that emerge directly from the brain.
Key Points
- > There are 31 pairs of spinal nerves in a human body.
- > There are 12 pairs of cranial nerves originating from the brain.
- > The 31 pairs are grouped as: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
- > The Sciatic nerve is the longest and thickest nerve in the human body.
- > The spinal cord primarily controls reflex actions.
- > The human vertebral column contains 33 vertebrae initially, which fuse to form 26 in adults.
Additional Information
Nerves in the Human Body
| Type of Nerve | Originates From | Number of Pairs |
|---|---|---|
| Cranial Nerves | Brain | 12 pairs |
| Spinal Nerves | Spinal Cord | 31 pairs |
| Total Peripheral Nerves | Brain + Spinal Cord | 43 pairs |
Memory Tips
- C before S: 'C' (Cranial) comes before 'S' (Spinal). Small number first, large number second. Cranial = 12, Spinal = 31.