GENERAL HISTOLOGY

Detailed explanation-1: -In total, there are 31 pairs of spinal nerves grouped regionally by spinal region. More specifically, there are eight cervical nerve pairs (C1-C8), twelve thoracic nerve pairs (T1-T12), five lumbar nerve pairs (L1-L5), 5 sacral (S1-S5), and a single coccygeal nerve pair.

Detailed explanation-2: -A myotome (greek: myo=muscle, tome = a section, volume) is defined as a group of muscles which is innervated by single spinal nerve root. Myotome testing is an essential part of neurological examination when suspecting radiculopathy.

Detailed explanation-3: -Answer and Explanation: The answer is (A): all spinal nerves are mixed. All spinal nerves carry both motor and sensory fibers. Motor fibers exit the spinal cord via the ventral roots, whereas the sensory fibers enter the spinal cord through the dorsal roots.

Detailed explanation-4: -Thus, all the spinal nerves are composed of both sensory and motor fibers (mixed nerves). There are eight cervical, twelve thoracic, five lumbar, five sacral nerves and one coccygeal nerve (all in pairs), each one emerging out of their corresponding intervertebral foramina (bony openings) of the vertebral canal.