The 12 Cranial Nerves - Vocabulary Reviewer

Vocabulary flashcards covering all 12 cranial nerves, their functional classifications, origins, clinical conditions, and anatomical characteristics.

Olfactory Nerve (CN I)

A special sensory cranial nerve responsible for smell that originates in the nasal mucosa and passes through the cribriform plate of the ethmoid bone.

Anosmia

Loss of smell; caused by nasal mucosa infection, head injury (fractured cribriform plate), meningitis, smoking, or cocaine use.

Optic Nerve (CN II)

A special sensory cranial nerve responsible for vision that passes through the optic chiasm and optic tracts to the optic cortex.

Anopia

A visual field defect or blindness resulting from fractures, brain lesions, multiple sclerosis (MS), pituitary tumors, or aneurysms.

Oculomotor Nerve (CN III)

A motor cranial nerve with the widest distribution among extrinsic eye muscles, responsible for eyeball and upper eyelid movement, accommodation for near vision, and pupil constriction.

Trochlear Nerve (CN IV)

The smallest cranial nerve; a somatic motor nerve originating in the midbrain that supplies only the superior oblique muscle of the eye.

Trigeminal Nerve (CN V)

The largest cranial nerve; a mixed nerve with three branches (Ophthalmic, Maxillary, Mandibular) responsible for facial sensations and chewing muscle motor function.

Trigeminal Neuralgia (tic douloureux)

A condition causing sharp, brief cutting pain, occurring almost exclusively in people over 60, linked to MS, diabetes, and vitamin B12 deficiency.

Abducens Nerve (CN VI)

A somatic motor cranial nerve originating in the pons that supplies the lateral rectus muscle to abduct or roll the eye laterally.

Facial Nerve (CN VII)

A mixed cranial nerve originating in the pons that controls muscles of facial expression, taste on the anterior 2/3 of the tongue, and tear and saliva secretion.

Bell's Palsy

Facial muscle paralysis characterized by loss of taste, decreased salivation, and an inability to close eyes even during sleep; caused by infection, trauma, tumors, or stroke.

Vestibulocochlear Nerve (CN VIII)

A purely sensory cranial nerve containing a vestibular branch for equilibrium/balance and a cochlear branch for hearing.

Vertigo

A clinical condition characterized by the sensation that oneself or the surrounding environment is rotating.

Ataxia

A clinical symptom defined as muscular incoordination.

Nystagmus

An involuntary, rapid movement of the eyeball.

Tinnitus

Ringing in the ears caused by injury to the cochlear branch of CN VIII.

Glossopharyngeal Nerve (CN IX)

A mixed cranial nerve emerging from the medulla oblongata that aids swallowing, parotid gland saliva production, and taste on the posterior 1/3 of the tongue.

Dysphagia

Difficulty in swallowing resulting from damage to nerves such as the Glossopharyngeal (IX) or Vagus (X) nerve.

Aptyalia

Reduced saliva secretion.

Ageusia

Loss of taste sensation.

Pharyngeal (gag) Reflex

A rapid, intense contraction of pharyngeal muscles to prevent choking, with sensory signals carried by CN IX and motor return via CN IX and CN X.

Vagus Nerve (CN X)

A mixed cranial nerve with the widest overall distribution in the body (head, neck, thorax, abdomen) that decreases heart rate, controls GI motility, and aids swallowing.

Tachycardia

An increased heart rate that can occur due to vagus nerve injury or vagal neuropathy.

Accessory Nerve (CN XI)

A motor cranial nerve whose fibers arise from the superior spinal cord (C1-C5) and exit via the jugular foramen to activate the sternocleidomastoid and trapezius muscles.

Hypoglossal Nerve (CN XII)

A somatic motor cranial nerve originating in the medulla that controls tongue movements necessary for speech, food manipulation, and swallowing.