Cranial Nerves

Question 1

CN I

Answer 1

Olfactory; exits thru cribiform plate; function: olfaction (test using noxious substance)

Question 2

CN II

Answer 2

Optic; exits thru optic canal; function: vision (acuity, fields, color), afferent limb of pupillary reflex (test using a near card, wiggling fingers for visual fields, light, fundoscopic exam)

Question 3

CN III

Answer 3

Oculomotor; exits thru skull: superior orbital fissure; function: superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae, efferent limb of papillary reflex (test with H in space)

Question 4

CN IV

Answer 4

Trochlear; exits thru skull: superior orbital fissure; superior oblique (test with H in space)

Question 5

CN V

Answer 5

Trigeminal; exits thru skull: superior orbital fissure (V1), foramen rotundum (V2), foramen ovale (V3); function: muscles of mastication, tensor tympani, tensor veli palatani, facial sensation, afferent limb of corneal reflexes (test with jaw opening, palpating over masseters bilaterally while jaw is clenched)

Question 6

CN VI

Answer 6

Abducens; exits thru skull: superior orbital fissure; function: lateral rectus (test with H in space)

Question 7

CN VII

Answer 7

Facial; Exits thru skull: internal auditory meatus; function: muscles of facial expression, stapedius, tase on anterior two-thirds of tongue, efferent limb of corneal reflex (test with raising eyebrows, squeeze eyes shut, show the teeth)

Question 8

CN VIII

Answer 8

Vestibulocochlear; exits thru skull: internal auditory meatus; function: hearing, vestibular function (test by whispering or rubbing fingers, Weber or Rinne tests, drift while patient is walking in place with eyes closed)

Question 9

CN IX

Answer 9

Glossopharyngeal; exits thru skull: jugular foramen; function: movement of palate, sensation over palate and pharynx, taste over posterior one-third of tongue, afferent limb of gag reflex (test with observation of palate elevation and hoarseness)

Question 10

CN X

Answer 10

Vagus; exits thru skull: jugular foramen; function: movement of palate, sensation over pharynx, larynx, and epiglottis, efferent limb of gag reflex, parasympathetic function of viscera (test with observation of palate elevation and hoarseness)

Question 11

CN XI

Answer 11

Accessory; exits thru skull: jugular foramen; function: sternocleidomastoid and trapezius movement (test by having pt turn head against resistance, shrug shoulders)

Question 12

CN XII

Answer 12

Hypoglossal; exits thru skull: hypoglossal foramen; function: tongue movement (test by sticking tonque out)