Biology · Neural Control and Coordination · NEET
| Origin | Arise from the brain | Arise from the spinal cord |
| Number in humans | 12 pairs | 31 pairs |
| Number in frog | 10 pairs | 10 pairs |
| System | Peripheral neural system (PNS) | Peripheral neural system (PNS) |
| Exit route | Through openings in the skull | Between vertebrae of the vertebral column |
| Myelination | Myelinated fibres | Myelinated fibres |
Both are part of the Peripheral Neural System (PNS), not the CNS. The CNS is only the brain and spinal cord. The nerves that come OUT of the brain (cranial) and OUT of the spinal cord (spinal) form the PNS. NCERT groups them clearly: PNS = cranial nerves + spinal nerves. Students often wrongly put cranial nerves in the CNS because they start at the brain, but the nerve itself is peripheral.
In humans there are 12 pairs of cranial nerves (arising from the brain) and 31 pairs of spinal nerves (arising from the spinal cord). Remember 12 and 31 as a pair. Do not confuse this with the frog, which has only 10 pairs of cranial nerves.
A frog has 10 pairs of cranial nerves; a human has 12 pairs. This exact point was asked in ReNEET 2026. NCERT states plainly: 'There are ten pairs of cranial nerves arising from the brain' for the frog. So if the question mentions frog, the answer is 10; if it mentions human, the answer is 12.
Cranial nerves originate directly from the brain (the cranium region). Spinal nerves originate from the spinal cord, emerging between the vertebrae of the vertebral column. This origin is the single cleanest way to tell them apart: brain = cranial, cord = spinal.
Yes. NCERT states that myelinated nerve fibres are found in spinal and cranial nerves. Myelination (Schwann cells forming a myelin sheath, with nodes of Ranvier) makes impulse conduction faster through saltatory conduction. This is a common one-liner NEET fact.
In frogs, the number of pairs of cranial nerves arising from the brain are ______.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Cranial nerves arise from the brain (12 pairs in humans), while spinal nerves arise from the spinal cord (31 pairs in humans). Both belong to the peripheral neural system.
Humans have 12 pairs of cranial nerves; frogs have 10 pairs. This frog-vs-human number is a favourite NEET trap.
Humans have 31 pairs of spinal nerves, which arise from the spinal cord and emerge through gaps in the vertebral column.
Yes. NCERT states that myelinated nerve fibres are found in spinal and cranial nerves, which allows fast saltatory conduction of impulses.
No. They belong to the peripheral neural system (PNS). Only the brain and spinal cord form the central neural system (CNS).
