Cranial Nerves - Location

BIOL319 Lab Study

Olfactory

(I) Beings in the upper nasal cavity and passes through the cribriform plate of the ethmoid bone. It synapses in the olfactory bulbs on each side of the longitudinal fissure of the brain. The fibers take information on the sense of smell and pass it through the olfactory tracts to be interpreted in the temporal lobe of the brain.

Optic

(II) Takes sensory information from the retina at the back of the eye and transmits the impulses through the optic canal in the sphenoid bone. Some fibers cross at the optic chiasm and pass via the optic tracts to the occipital lobe, where vision is interpreted.

Oculomotor

(III) Emerges from the surface of the brain near the midline and just anterior to the pons. It passes through the superior orbital fissure, innervates the inferior oblique muscle and the medial, superior, and inferior rectus muscles; it carries parasympathetic fibers to the lens and iris.

Trochlear

(IV) Is at the sides of the pons at about a 45 degree angle from the midline of the brain. It passes through the superior orbital fissure to the superior oblique muscle.

Trigeminal

(V) Is at a 90 degree angle from the midline at the lateral sides of the pons. The trigeminal has three branches: (1) The ophthalmic branch passes through the superior orbital fissure; (2) the maxillary branch passes through the foramen rotundum of the sphenoid bone; (3) the mandibular branch passes through the foramen ovale of the sphenoid bone and enters the mandible by the mandibular foramen and exits by the mental foramen.

Abducens

(VI) Begins at the midline junction between the pons and the medulla oblongata and passes through the superior orbital fissure to carry motor information to the lateral rectus muscle of the eye.

Facial

(VII) Begins as the first of a cluster of nerves on the anterolateral part of the medulla oblongata. It passes through the internal auditory meatus and through the inner ear to the stylomastoid foramen of the temporal bone to innervate facial muscles and glands. It receives sensory information from the anterior tongue. Sensory information of the tongue is interpreted in the temporal lobe of the brain.

Vestibulocohlear

(VIII) Comes from the inner ear and passes through the internal auditory meatus. The conduction passes to the pons, and hearing and balance are interpreted in the temporal lobe.

Glossopharyngeal

(IX) Passes through the jugular foramen to innervate muscles of the throat (pharyngeal branches) and the tongue (glossal branches). Motor portions of the nerve control some muscles of swallowing and salivary glands, whereas sensory nerves receive information from the posterior tongue and from baroreceptors of the carotid artery.

Vagus

(X) Passes through the jugular foramen and along the neck to the larynx, heart, and abdominal region. The sensory impulses travel in this nerve from the viscera in the abdomen, the thorax, the neck, and the root of the tongue to the brain.Ac

Accessory

(XI) Multiple fibers arise from the lateral sides of the medulla oblongata and pass through the jugular foramen to numerous muscles of the neck.H

Hypoglossal

(XII) Begins at the anterior surface of the medulla and passes through the hypoglossal canal to innervate the muscles of the tongue/