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Table 7.     Functions of the cranial nerves.

This table includes functional components that can be tested by clinical examination or that cause symptoms if affected by disease. Physiological afferents from internal organs¹ are omitted from the table.

  Functional components
Cranial nerve Motor (= supplying skeletal muscle) Preganglionic parasympathetic² General sensory (skin, mucous membranes) Special senses
I     Olfactory       Smell
II    Optic       Vision
III   Oculomotor Eye movements other than those mediated by IV & VI. Elevation of upper eyelid Constriction of pupil (ciliary ganglion)    
IV    Trochlear Certain downward eye movements      
V     Trigeminal Muscles that open and close the mouth; tensor tympani muscle of middle ear Skin of face; mouth, teeth, nose, sinuses, dura mater of anterior and middle fossa    
VI    Abducens Abduction of eye      
VII   Facial Muscles of face; stapedius muscle of middle ear Lacrimal and nasal glands (pterygopalatine ganglion); sublingual & submandibular salivary glands (submandibular ganglion) Part of external ear and tympanic membrane Taste: palate & anterior two thirds of tongue
VIII  Vestibulocochlear:
    Vestibular
    Cochlear
      Equilibration
Hearing
IX    Glossopharyngeal Stylopharyngeus muscle Parotid gland (otic ganglion) Pharynx, middle ear, posterior third of tongue Taste: posterior third of tongue
X     Vagus Muscles of larynx & pharynx Slows heart (cardiac ganglia); increases gastric acid secretion and empties stomach (enteric nervous system) Larynx, trachea, oesophagus, dura of posterior fossa; part of external ear and tympanic membrane Taste: epiglottis
XI    Accessory³ (Spinal component) Trapezius and sternocleidomastoid muscles      
XII   Hypoglossal Muscles that move the tongue      

Footnotes to Table 7

¹ Afferent fibers in IX and X are of great importance for regulation of cardiovascular and respiratory function, but they do not give rise to conscious sensations, and the physiological functions are not usually disturbed by unilateral lesions that affect the nerves or their central connections.

² The names of the parasympathetic ganglia are indicated in parentheses after the functions.

³ The small cranial root of XI carries motor axons destined mostly for the larynx. These cross over into X by way of a communicating branch, as the two nerves pass through the jugular foramen in the base of the skull. The fibers of the spinal root have their cell bodies in segments C1-C5 of the spinal cord.


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Last updated: January 2003