Question

If cranial nerves: 12 pairs, then spinal nerves
A) 30 pairs
B) 31 pairs
C) 32 pairs
D)33 pairs

Answer 1

Cranial nerves emerge directly from the brain and the spinal nerves initiate from the spinal cord.

Complete answer:
The Cranial and spinal nerves are primarily responsible for the sensory and motor functions of the neck and head. Nerves attached to the brain are the cranial nerves. There are twelve cranial nerves, CNI-XII. They can be classified as sensory nerves, motor nerves, or a combination of both. The axons in these nerves originate from sensory ganglia which is external to the cranium or from the motor nuclei within the brain cells. Sensory axons enter the brain and have their synapses in a nucleus of the cell. Motor axons connect to skeletal muscles of the head or neck. Three of the nerves are solely composed of sensory fibers; five are strictly motor; and the remaining four are mixed nerves.
The nerves connected to the spinal cord are the spinal nerves. The arrangement of these nerves is less complex than that of the cranial nerves. Sensory and motor axons combine to separate into two nerve roots and form all the spinal nerves. Dorsal nerve root is formed by the sensory axons entering the spinal cord. The motor fibers, both somatic and autonomic combine as the ventral nerve root.
There are 31 spinal nerves. These are

eight pairs of cervical nerves (C1 to C8),
twelve thoracic nerves (T1 to T12),
five pairs of lumbar nerves (L1 to L5),
five pairs of sacral nerves ( S1 to S5) and
one pair of coccygeal nerves.

Note: All the nerves are responsible for the conduction of sensory and motor impulses all throughout the body. The sensory neurons take the chemical impulse signals up to the brain and bring down electrical impulses via the motor neurons to the respective muscles.