COMPONENTS

 

Functionally, the cranial nerves are classified as motor or sensory. Being each one somatic and visceral.

 

 

The motor component:

 

The motor fibers that innervate muscles not associated with branchial arches form the general somatic efferent component (GSE). These are:  The extrinsic muscles of the eye (III, IV and VI cranial nerves); the muscles derived from somites (trapezius, omotransversarius, sternocephalicus and cleidocephalicus) (XI cranial nerve); and the muscles of the tongue, and the thyrohyoideus and geniohyoideus muscles (XII cranial nerve).

 

The motor fibers that innervate muscles associated with branchial arches form the special visceral efferent component (SVE). These are: masticatory, facial, pharyngeal, laryngeal and some hyoideal muscles (V, VII, IX, X, and XI cranial nerves).

 

The autonomic nervous system fibers that innervate intrinsic muscles of the eye, heart, vessels, viscera and glands (III, VII, IX, X and XI cranial nerves) form the general visceral efferent component (GVE).

 

 

The sensory component:

 

The sensory fibers coming from the skin and musculoskeletal receptors (V, VII and X cranial nerves) form the general somatic afferent component (GSA).

 

The fibers for the sense of sight coming from the retina (II cranial nerve), and for the senses of equilibrium and hearing coming from the inner ear (VIII cranial nerve) form the special somatic afferent component (SSA).

 

The sensory fibers from viscera and heart (VII, IX and X cranial nerves) make up the general visceral afferent component (GVA). The fibers for the sense of taste (VII, IX and X cranial nerves) form the special visceral afferent component (SVA). The sense of smell (I cranial nerve) is also considered an SVA.

 

It is important to point out that the components of some different cranial nerves intermingle in order to reach their destinations.