Special somatic afferent
Special somatic afferent (SSA) refers to afferent nerves that carry information from the special senses of vision, hearing and balance. The cranial nerves containing SSA fibers are the optic nerve (II) and the vestibulocochlear nerve (VIII). "SSA" may also stand for "special sensory afferent", but this term encompasses both special somatic and special visceral afferents.