innervate

Innervate (verb): to supply an organ, tissue, or region with nerves; to provide with nerve fibers or to stimulate with nerves. In anatomy, the term describes the nerve supply to a body part. The noun innervation refers to the distribution or supply of nerves to that part. For example, the muscles of facial expression are innervated by the facial nerve (cranial nerve VII), and the skin of a dermatomal region is innervated by a specific spinal nerve.

Innervation arises from developing nerve fibers that extend from neurons to their targets and form functional connections. There are two broad patterns: somatic innervation, which involves motor and sensory nerves to skeletal muscles and skin; and autonomic innervation, which includes sympathetic and parasympathetic fibers supplying organs and blood vessels. In a muscle, motor neurons create neuromuscular junctions; in the skin, sensory endings connect with cutaneous receptors; autonomic innervation typically modulates function rather than driving contraction.

Clinically, innervation status is a key diagnostic and therapeutic factor. Nerve injury or disease can disrupt innervation, causing loss of sensation, paralysis, or dysautonomia. Recovery depends on axonal regrowth and reinnervation of targets, sometimes aided by nerve grafts or nerve transfers. Mapping patterns of innervation, such as dermatomes and myotomes, supports localization and surgical planning. Researchers also study innervation through electrophysiology and imaging.

Etymology: innervate derives from Latin innervare, in- "in" + nervus "nerve," meaning to furnish with nerves.