Term
| Cranial Nerve I - Olfactory nerve |
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Definition
| The sense of smell. There are numerous olfactory nerves that relay sensory impulses of smell from the membranes of the nasal cavity. Damage to these nerves results in a loss of smell. |
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Term
| Cranial Nerve II - Optic Nerve |
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Definition
| Vision. This is a sensory-only nerve that conducts impulses fromt he retina of the eye. It originates in the back of the eyeball, and damage to these nerves results in blindness. |
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Term
| Cranial Nerve III - Oculomotor Nerve |
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Definition
| This nerve controls all movement of the eyeballs. It is primarily a motor nerve. It comes out of the midbrain and serves four of the six eye muscles, as well as the muscle of the eyelid, the iris (which causes pupil dilation), and the ciliary body. Damage to these nerves can cause a droopy eyelid, constant dialted pupil, or the inability to rotate the eyeball. |
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Term
| Cranial Nerve IV - Trochlear Nerve |
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Definition
| This is a very small nerve, both sensory and motor, that innervates the superior oblique muscle of the eye. |
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Term
| Cranial Nerve V - Trigeminal Nerve |
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Definition
| This is the largest of the cranial nerves. It is primarily sensory, but does send motor impulses to the muscles of mastication (chewing). |
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Term
| Cranial Nerve VI - Abducens Nerve |
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Definition
| This is a small nerve that provides both motor and sensory innervation to the lateral rectus eye muscle. Damage to this nerve causes the eyeball to be pulled medially, and makes it unable t move laterally at all. |
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Term
| Cranial Nerve VII - Facial Nerve |
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Definition
| This is a mixed nerve. The motor fibers innervate facial, scalp, and superficial neck muscles. The salivary glands are also innervated by this. The sensory fibers arise from the taste buds on the tongue. Damage to these nerves distorts taste perception, particularly with sweets, and causes the face to sag. |
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Term
| Cranial Nerve VIII - Vestibulocochlear Nerve |
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Definition
| Hearing and equilibrium. This is also called the acoustic nerve. It is a sensory nerve that arises within the inner ear. The vestibular branch controls equilibrium and balance, while the cochlear portion controls hearing. Damage to these nerves can cause deafness or dizziness and inability to maintain balance. |
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Term
| Cranial Nerve IX - Glossopharyngeal Nerve |
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Definition
| This is a mixed neve that innervates the tongue and pharynx. The sensory portion transmits impulses from the tonsils, salivary gland, and back third of the tongue. The motor fibers innervate the muscles of the pharynx that help with swallowing. Damage to these nerves would result in a loss of bitter and sour taste, or could cause difficulty swallowing. |
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Term
| Cranial Nerve X - Vague Nerve |
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Definition
| This arises from the medulla and has both motor and sensory fibers that serve autonomic organs of the thoracic and abdominal cavities. It is associated with such functions as breathing, heartbeat, hunger pangs, and peristalsis. One of its branches supplies the larynx and controls speech. Damage to both of these nerves would result in death; damage to only one would affect speech and swallowing. |
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Term
| Canial Nerve XI - Accessory Nerve |
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Definition
| This is a motor nerve only. It innervates the muscles of the pharyngeal region as well as the sternocleidomastoid and trapezius muscles. Damage to this nerve would make it difficult to rotate the head or shrug the shoulders. |
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Term
| Cranial Nerve XII - Hypoglossal Nerve |
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Definition
| This supplies motor fibers to the muscles of the tongue. Damage would cause difficulty speaking, swallowing, or ticking out the tongue. |
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