cranial nerves and spinal nerves

Cranial Nerves

Twelve pairs of nerves that connect to the brain, mostly the brainstem, and are identified by name or number.

Olfactory nerve (I)

Carries information about the sense of smell.

Optic nerve (II)

Carries visual information from the eyes to the brain.

Oculomotor nerve (III)

Innervates the muscles of the eye and regulates the amount of light entering the eye.

Trochlear nerve (IV)

Innervates the superior oblique muscles of the eye.

Trigeminal nerve (V)

Innervates the muscles of mastication and carries sensory information from the head and teeth.

branches of trigeminal nerve

ophthalmic nerve, maxillary nerve, and mandibular nerve.

Abducens nerve (VI)

Innervates the lateral rectus muscles of the eye.

Facial nerve (VII)

Innervates the muscles of the face and scalp and carries sensory information from taste buds of the anterior two-thirds of the tongue.

Vestibulocochlear nerve (VIII)

Carries sensory information related to equilibrium and hearing.

divisions of Vestibulocochlear nerve

vestibular and cochlear nerve

Glossopharyngeal nerve (IX)

Innervates the pharynx and carries sensory information from taste buds of the posterior third of the tongue.

Vagus nerve (X)

Innervates various organs in the body and carries sensory information from the pharynx, larynx, trachea, heart, lungs, esophagus, stomach, small intestine, and gallbladder.

Accessory nerve (XI)

Innervates the trapezius and sternocleidomastoid muscles.

Hypoglossal nerve (XII)

Innervates the muscles of the tongue.

Spinal Nerves

Thirty-one pairs of nerves connected to the spinal cord, numbered by the level of the vertebral column at which they emerge.

Nerve pairs in order from cervical to coccygeal

8, 12, 5, 5, 1.

Cauda equina

describes the appearance of the lower end of the spinal cord and its spinal nerves as a horse’s tail.

Nerve Plexuses

Complex networks formed by the ventral rami of most spinal nerves, subdividing and joining together to form individual nerves.

Cervical plexus

5 pairs of spinal nerves located deep within the neck.

Dermatomes

Regions of the skin surface area supplied by sensory fibers of a given spinal nerve.

Myotomes

Skeletal muscles supplied by motor fibers of a given spinal nerve.