Review of the Spinal Nerve
The four functional components (and neurons) of a typical ventral or dorsal ramus of a spinal nerve and it's muscular (motor) branches
GSA (pseudounipolar in the spinal ganglion)
GSE (multipolar in the ventral horn of spinal cord)
GVA (pseudounipolar in the spinal ganglion)
GVE postganglionic (multipolar in the sympathetic chain ganglion)
The functional components (and neurons) of a typical cutaneous nerve
Same as a typical dorsal or ventral ramus EXCEPT NO GSE (multipolar in the ventral horn of spinal cord)
EXPLANATION: NO skeletal muscle is found in the SKIN EXCEPT in the face and neck. This skeletal muscle is innervated by a cranial nerve and NOT spinal nerves.
Dermatome
The area of SKIN supplied by ONE spinal nerve. It is distributed by 3 or MORE CUTANEOUS BRANCHES of the SPINAL NERVE. The nerve cell bodies for the neurons supplying exteroceptive GSA fibers to the dermatome are found within the spinal ganglion for the spinal nerve.
Myotome
The portion of a SKELETAL MUSCLE supplied by ONE spinal nerve and its contiguous spinal cord segment. Generally, two or more myotomes unite during embryonic development to form each named skeletal muscle. Therefore, definitive skeletal muscles are innervated by two or more spinal nerves. Ventral rami of these nerves form somatic plexuses, i.e., cervical, brachial, and lumbosacral. The nerve cell bodies for the neurons supplying the myotome are located within the ventral horn (GSE) of the grey matter for the spinal cord and within the spinal ganglia (proprioceptive GSA).