GENERAL HISTOLOGY

Detailed explanation-1: -Somatic motor neurons. Somatic MNs are located in the Rexed lamina IX in the brainstem and the spinal cord and innervate skeletal muscles responsible for movements (Rexed, 1954). MNs form coherent groups connecting to a unique muscle target defined as MN pools.

Detailed explanation-2: -Overview. Skeletal (striated) muscle contraction is initiated by “lower” motor neurons in the spinal cord and brainstem. The cell bodies of the lower neurons are located in the ventral horn of the spinal cord gray matter and in the motor nuclei of the cranial nerves in the brainstem.

Detailed explanation-3: -Lamina VII is equivalent to the intermediate zone and acts as a relay between muscle spindle to midbrain and cerebellum, and laminae VIII-IX comprise the ventral horn and contain mainly motor neurons. The axons of these neurons innervate mainly skeletal muscle.

Detailed explanation-4: -The marginal nucleus of spinal cord, or posteromarginal nucleus, Rexed lamina I, is located at the most dorsal aspect of the dorsal horn of the spinal cord. The neurons located here receive input primarily from Lissauer’s tract and relay information related to pain and temperature sensation.