Cranial Nerves, Dermatomes etc.

Question 1

Nerve I

Answer 1

• olfactory
• smell
• through cribriform plate

Question 2

Nerve II

Answer 2

• optic
• sight
• optic canal

Question 3

Nerve III

Answer 3

• oculomotor
• eye movement (medial rectus, inferior oblique, superior rectus, inferior rectus), pupil construction, accommodation, eyelids
• palsy: ptosis, down and out eye, dilated, fixed pupil
• through superior orbital fissure

Question 4

Nerve IV

Answer 4

• trochlear
• eye movement (superior oblique)
• palsy: defective downward gaze - vertical diplopia
• superior orbital fissure

Question 5

Nerve VI

Answer 5

• abducens
• eye movement (lateral rectus)
• palsy: defective abduction - horizontal diplopia
• superior orbital fissure

Question 6

Nerve VII

Answer 6

• facial
• facial movement
• taste (anterior 2/3 of tongue)
• lacrimation
• salivation
• lesion: flaccid paralysis of upper and lower face, loss of corneal reflex, loss of taste, hyperacusis
• internal auditory meatus

Question 7

Nerve VIII

Answer 7

• vestibulocochlear
• hearing and balance
• hearing loss, vertigo, nystagmus, acoustic neuromas = Scwann cell tumours of cochlear nerve
• internal auditory meatus

Question 8

Nerve IX

Answer 8

• taste (posterior 1/3 of tongue), salivation, swallowing, mediates input from carotid body and sinus
• lesion: hypersensitive carotid sinus reflex, loss of gag reflex
• jugular foramen

Question 9

Nerve X

Answer 9

• vagus
• phonation, swallowing innervates viscera
• lesions: uvula deviates from site of lesion, loss of gag reflex
• jugular foramen

Question 10

Nerve XI

Answer 10

• accessory
• head and shoulder movement
• lesion: weakness turning head to contralateral side
• jugular foramen

Question 11

Nerve XII

Answer 11

• hypoglossal
• tongue movement
• tongue deviates towards side of lesion
• hypoglossal canal

Question 12

Corneal reflex: (afferent and efferent limb)

Answer 12

• ophthalmic

- facial

Question 13

Jaw jerk:

Answer 13

• mandibular
• mandibular
• exaggerated response may indicate upper motor neurone lesion

Question 14

Gag reflex:

Answer 14

• glossopharyngeal

- vagal

Question 15

Carotid sinus:

Answer 15

• glossopharyngeal

- vagal

Question 16

Pupillary light:

Answer 16

• optic

- oculomotor

Question 17

Lacrimation:

Answer 17

• ophthalmic

- facial

Question 18

Nerve V

Answer 18

• trigeminal
• facial sensation, mastication
• lesions: trigeminal neuralgia, loss of corneal reflex, loss of facial sensation, paralysis of mastication muscles, deviation go jaw towards weak side
• V1 - superior orbital fissure
• V2 - foramen rotundum
• V3 - foramen ovale

Question 19

What is the median nerve formed by?

Answer 19

-lateral root (C5,6,7)
-medial (C8 and T1)
of brachial plexus

Question 20

Damage of median nerve at wrist:

Answer 20

• e.g. carpal tunnel
• paralysis and wasting of thenar eminence muscles and opponents pollicis
• sensory loss to palmar aspect of lateral 2 1/2 fingers

Question 21

Damage of median nerve at elbow:

Answer 21

• as at wrist
• unable to pronate forearm
• weak wrist flexion
• ulnar deviation of wrist

Question 22

Damage of median nerve - anterior interosseous nerve:

Answer 22

• leaves just below elbow

- loss of pronation of forearm and weakness of long flexors of thumb and index finger