There are five functional divisions of the nervous system.
Formerly the basis of classification was the division into somatic and autonomic (visceral) systems with sensory (afferent) and motor (efferent) subdivisions. The neurons of one of these divisions are restricted to the head; these belong to the special visceral efferent (SVE) neuronal component (also called branchial efferent).
These neurons innervate the muscles developed from the pharyngeal arches and contribute to:• The trigeminal nerve supplying the chewing muscles
• The facial nerve supplying the facial muscles
• Cranial nerves IX and X-XI supplying pharyngeal and laryngeal muscles.
There are no SVE neurons supplying the organs or tissues of the abdomen and pelvis.
The division between somatic and autonomic components of the nervous system becomes extremely difficult since many bodily functions involve both somatic (e.g. skeletal muscles) and autonomic activity (e.g. adjustments in blood circulation). In summary, motor (efferent) axons innervating skeletal muscle are somatic, whereas axons innervating smooth muscle and glandular tissue are autonomic.
11.1