Review of Cranial Nerves

The brain controls a variety of functions in the body, and this is primarily accomplished through the twelve pairs of cranial nerves. These nerves are responsible for the transmission of sensory and motor information between the brain and the rest of the body, making them an essential part of the body’s functioning. Below is a review of the anatomy and function of the twelve cranial nerves.

Olfactory Nerve (CN I)

The olfactory nerve (CN I) is responsible for the sense of smell. The olfactory nerve is composed of both sensory and motor neurons, with the sensory neurons located in the olfactory epithelium of the nasal cavity. These neurons transmit impulses from the olfactory cells to the olfactory bulb, located in the brain. In turn, this information is transferred to the cerebrum for interpretation and processing.

Optic Nerve (CN II)

The optic nerve (CN II) is responsible for the sense of sight and is composed of sensory neurons located in the retina of the eye. These neurons transmit electrical impulses from the eye to the brain, where they are processed and interpreted in the occipital lobe. The optic nerve is responsible for the transmission of visual information, but does not play a role in the production of images.

oculomotor nerve (CN III)

The oculomotor nerve (CN III) is composed of both motor and sensory neurons. The motor neurons of the oculomotor nerve originate in the midbrain and are responsible for the movement of the eyes. These neurons transmit impulses to the extraocular muscles of the eye, which control the direction of the gaze. The sensory neurons of the oculomotor nerve originate in the retina and transmit information regarding the position of the eyes to the midbrain.

Trochlear Nerve (CN IV)

The trochlear nerve (CN IV) is composed of motor neurons that originate in the midbrain. These neurons transmit impulses to the superior oblique muscle of the eye, which is responsible for the movement of the eye. The trochlear nerve is responsible for the movement of the eye in a downward and outward direction.

Trigeminal Nerve (CN V)

The trigeminal nerve (CN V) is composed of both sensory and motor neurons. The sensory neurons are located in the face, and transmit information regarding temperature, pain, and touch to the brain. The motor neurons of the trigeminal nerve originate in the brainstem and are responsible for the movement of the muscles of the face and jaw.

Abducent Nerve (CN VI)

The abducent nerve (CN VI) is composed of motor neurons that originate in the pons region of the brain. These neurons transmit impulses to the lateral rectus muscle of the eye, which is responsible for the movement of the eye in an outward direction.

Facial Nerve (CN VII)

The facial nerve (CN VII) is composed of both motor and sensory neurons. The motor neurons of the facial nerve originate in the pons and are responsible for the movement of the facial muscles. The sensory neurons are located in the skin of the face and transmit information regarding temperature and touch to the brain.

Vestibulocochlear Nerve (CN VIII)

The vestibulocochlear nerve (CN VIII) is composed of both sensory and motor neurons. The sensory neurons of the vestibulocochlear nerve are located in the inner ear and are responsible for the transmission of auditory and balance information to the brain. The motor neurons of the vestibulocochlear nerve originate in the brainstem and are responsible for the movement of the muscles of the middle ear.

Glossopharyngeal Nerve (CN IX)

The glossopharyngeal nerve (CN IX) is composed of both sensory and motor neurons. The sensory neurons are located in the mouth and throat and transmit information regarding taste and touch to the brain. The motor neurons of the glossopharyngeal nerve originate in the brainstem and are responsible for the movement of the muscles of the tongue and throat.

Vagus Nerve (CN X)

The vagus nerve (CN X) is composed of both sensory and motor neurons. The sensory neurons of the vagus nerve are located in the organs of the chest and abdomen and are responsible for the transmission of information regarding pain, temperature, and touch to the brain. The motor neurons of the vagus nerve originate in the brainstem and are responsible for the movement of the muscles of the throat, chest, and abdomen.

Accessory Nerve (CN XI)

The accessory nerve (CN XI) is composed of motor neurons that originate in the brainstem. These neurons transmit impulses to the sternocleidomastoid and trapezius muscles of the neck and are responsible for the movement of the neck.

Hypoglossal Nerve (CN XII)

The hypoglossal nerve (CN XII) is composed of motor neurons that originate in the brainstem. These neurons transmit impulses to the muscles of the tongue and are responsible for the movement of the tongue.

In summary, the twelve pairs of cranial nerves are responsible for the transmission of sensory and motor information between the brain and the rest of the body. The olfactory nerve is responsible for the sense of smell, the optic nerve is responsible for the sense of sight, and the remaining ten pairs of cranial nerves are responsible for the movement of the muscles of the head, neck, and face.