It also controls the movement of muscles within your jaw and ear. It sends sensory information from your ears, lower lip, and chin. The mandibular division has both a sensory and a motor function. This division communicates sensory information from the middle part of your face, including your cheeks, upper lip, and nasal cavity. The ophthalmic division sends sensory information from the upper part of your face, including your forehead, scalp, and upper eyelids. The trigeminal nerve has three divisions, which are: The trigeminal nerve is the largest of your cranial nerves and has both sensory and motor functions. Like your oculomotor nerve, it moves forward until it reaches your eye sockets, where it stimulates the superior oblique muscle. It emerges from the back part of your midbrain. This is the muscle that’s in charge of downward, outward, and inward eye movements. The trochlear nerve controls your superior oblique muscle. It moves forward from that area until it reaches the area of your eye sockets. This nerve originates in the front part of your midbrain, which is a part of your brainstem. It also helps to control the size of your pupil as it responds to light. These muscles help your eyes move and focus on objects. Your oculomotor nerve provides motor function to four of the six muscles around your eyes. The oculomotor nerve has two different motor functions: muscle function and pupil response. Your visual cortex is located in the back part of your brain. Through each optic tract, the nerve impulses eventually reach your visual cortex, which then processes the information. At the optic chiasm, nerve fibers from half of each retina form two separate optic tracts. Once inside your skull, both of your optic nerves meet to form something called the optic chiasm. The information received by your rods and cones is sent from your retina to your optic nerve. They have a lower light sensitivity than rods and are more involved with color vision. They’re more specialized for black and white or night vision.Ĭones are present in smaller numbers. Rods are found in large numbers and are highly sensitive to light. When light enters your eye, it comes into contact with special receptors in your retina called rods and cones. The optic nerve is the sensory nerve that involves vision. Nerve signals are then sent to areas of your brain concerned with memory and recognition of smells. Your olfactory bulb is an oval-shaped structure that contains specialized groups of nerve cells.įrom the olfactory bulb, nerves pass into your olfactory tract, which is located below the frontal lobe of your brain. It stimulates receptors that generate nerve impulses that move to your olfactory bulb. This lining is called the olfactory epithelium. When you inhale molecules with a scent, known as aromatic molecules, they dissolve in a moist lining at the roof of your nasal cavity. The olfactory nerve sends sensory information to your brain about smells that you encounter. Injury, trauma, and whiplash can also cause damage to cranial nerves.Ĭranial nerve function I. These are tumors that can form in the skull and affect different cranial nerves. This condition affects the ninth cranial nerve and can cause pain at the base of the tongue that may travel to the ear and neck. A hemifacial spasm happens when blood vessels constrict the seventh cranial nerve and cause a facial spasm or tic. Bell’s palsy, a disorder of the seventh cranial nerve, can cause temporary weakness or paralysis in one side of the face. This type of palsy can cause the eye to cross inward toward the nose. This disorder can cause misalignment of the eyes and can affect one or both eyes. Fourth nerve palsy or superior oblique palsy.Trigeminal neuralgia is a disorder of the fifth cranial nerve and typically causes pain on one side of the face. This disorder can cause a closed or partially closed eyelid, an enlarged pupil, and the movement of the eye outward and downward. If a sensory nerve is affected, it can cause pain or reduced sensation.Ĭonditions and disorders that affect the cranial nerves can include: They can also change the way you perceive sensation on the face and prevent or alter the movement of the head, eyes, neck, shoulders, throat, and tongue.Ĭranial nerve palsy affects a motor nerve - one that controls movement. What conditions and disorders affect the cranial nerves?Ĭonditions and disorders of the cranial nerves can affect processes that involve vision, smell, hearing, speaking, and balance.
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