exam 4 anatomy

occulomotor nerve def. & #

the third of 12 pairs of cranial nerves in the brain. This nerve is responsible for eyeball and eyelid movement. It follows the olfactory and optic nerves in terms of order. this nerve involves two separate components, each of which has a distinct function. *motor and PS fibers*

optic nerves def. & #

this nerve is located in the back of the eye. It is also called the second cranial nerve or cranial nerve II. It is the second of several pairs of cranial nerves. The job of the optic nerve is to transfer visual information from the retina to the vision centers of the brain via electrical impulses. *purely sensory*

dorsal roots

is a main bundle of nerve fibers that branches off the spinal cord and goes to other areas of the body. These roots are responsible for carrying signals of sensation (such as feelings of pain and temperature) from the body to the brain.

ventral roots

is a type of nerve root that branches off the spinal cord, exits the spinal column, and continues on its path to specific areas of the body.

trochlear nerve def. & #

is also known as cranial nerve IV (CN-IV). It is the only cranial nerve that emerges dorsally from the brain. CN-IV passes through the superior orbital fissure, and it provides motor function, or movement. It serves the superior oblique eye muscle and connects to the annular tendon. As a result, it processes brain signals to move the eyes up and down, and also outwards. *motor*

Abducens nerve def. & #

is also known as the abducent or sixth cranial nerve (CN6). It controls the eye's lateral rectus muscle, which moves the eye sideways, away from the nose. *motor*

facial nerve def. & #

is also known as the seventh cranial nerve (CN7). This nerve performs two major functions. It conveys some sensory information from the tongue and the interior of the mouth. Specifically, CN7 serves about two-thirds of the tongue's tip. The nerve extends from the brain stem, at the pons and the medulla. Also, this nerve innervates facial muscles, controlling how to contract and produce facial expressions. *mixed- sensory and motor*

vagus nerve def. & #

is one of 12 cranial nerves. It is the longest of the cranial nerves, extending from the brainstem to the abdomen by way of multiple organs including the heart, esophagus, and lungs. Also known as cranial nerve X. it forms part of the involuntary nervous system and commands unconscious body procedures, such as keeping the heart rate constant and controlling food digestion. *mixed - sensory and motor*

vestibulocochlear nerves def. & #

is the eighth of twelve cranial nerves. This group includes all the nerves that emerge from the cranium (skull), as opposed to those that emerge from the vertebral column (spinal cord). It is a paired set of nerves (one from each ear) and the nerve is located in the internal auditory canal, a part of the skull's temporal bone. this nerve is responsible for both hearing and balance and brings information from the inner ear to the brain. *primarily sensory*

trigeminal nerve def. & #

is the fifth cranial nerve located within the brain, and is primarily responsible for transmitting sensations from the face to the brain. It is composed of three branches: the ophthalmic, maxillary, and mandibular. Each branch connects nerves from the brain to different parts of the face. *mixed- sensory and motor*

hypoglossal nerves def. & #

is the twelfth cranial nerve and controls movements of the tongue. the path of the nerve starts in the nucleus of the brainstem, which is located near the midline of the medulla oblongata, and then travels between the carotid artery and jugular vein to end up on the underside of the tongue. *motor*

somatic motor

supplies four extraocular muscles in the eye and the upper eyelid's levator palpebrae superioris with motor (movement) fibers. It controls the muscles that allow for visual tracking and fixation by the eye. Visual tracking is the ability to follow an object as it moves across the field of vision. Fixation is the ability to focus on a stationary object.

visceral motor

controls parasympathetic innervation (nerves related to involuntary actions) of the ciliary muscles and constrictor papillae, aiding in accommodation and pupillary light reflexes. Accommodation is the ability of the eye to keep an object in focus as the object's distance from the eye changes. Pupillary light reflexes are automatic changes in dilation (size) of the pupil, which regulate the amount of light that enters the eye, making sure the light is enough to see but not too bright.

dorsal ramus

innervate muscles and blood vessels of the back (posterior/dorsal surface of the trunk).

ventral ramus

innervate the muscles and blood vessels of the anterolateral aspects of the body wall.

glossophaeyngeal nerve def. & #

(CN IX) is a paired set of nerves, which is part of the 24 cranial nerves. These nerves are arranged in twelve pairs, of which the glossopharyngeal is the ninth. The pairs of cranial nerves, in order, are: the olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal. This nerve connects to the brainstem at the upper medulla, travels through the base of the skull at the jugular foramen, and ends in the mouth in the mucous glands, palatine tonsil, and the base of the tongue. *mixed - sensory and motor*

accessory nerve def. & #

(CN XI) is a cranial nerve that controls the movement of certain neck muscles. It is coiled in appearance. It is divided into spinal and cranial divisions, but its cranial part is often disregarded. this nerve provides motor function to the sternocleidomastoid muscle, which extends the neck and the trapezius, as well as the upper back and shoulder. *motor*

olfactory nerves def. & #

Also known as CN1, this is the first of 12 cranial nerves located within the head. It relays sensory data to the brain, and it is responsible for the sense of *smell.* *purely sensory*