Cranial nerves Flashcards
III (oculomotor)
Function:
1) Eye movement: MR, IO, SR, IR
2) Pupil constriction
3) Accommodation
4) Eyelid opening
Foramen: superior orbital fissure
Features of palsy :
- eye down and out
- ptosis (drooping of upper eye lid)
- pupil may be dilated (surgical 3rd nerve palsy)
Causes of palsy:
- DM
- Vasculitis: GCA, SLE
- Posterior communicating artery aneurysm - pupil dilated, often associated pain
- carvenous sinus thrombosis
- Weber’s syndrome - ipsilateral 3rd nerve palsy with CL hemiplegia - mid brain stroke
- Amyloid, MS
- false localising sign due to uncal herniation through tentorium if raised ICP - more likley 6th nerve palsy
IV (trochlear)
Function: eye movement (SO)
Foramen: SOF.
Palsy: defective downward gaze –> vertical diplopia
V (trigeminal)
Function: facial sensation, mastication
Lesions may cause:
- trigeminal neuralgia
- loss of corneal reflex (afferent)
- loss of facial sensation
- paralyisis of mastication muscles
- - deviation of jaw to weak side
V1: SOF
V2: forament rotundum
V3: foramen ovale
VI (abducens)
Function: eyemovement (LR
Palsy: defective abduction –> horizontal diplopia
Foramen: SOF
VII (Facial)
Function: facial movement, tast anterior 2/3 tongue, lacrimation, salivation
Lesions may result in:
- flaccid paralysis of upper and lower face
- loss of corneal reflex (efferent)
- loss of taste
- hyperacusis
Foramen: internal auditory meatus
VIII (vestibulocochlear)
Function: hearing, balance
Lesion:
- hearing loss
- vertigo
- acoustic neuromas - Schwann cell tumour of cochlear nerve
Foramen: internal auditory meatus
IX (glossopharyngeal)
Function: taste posterior 2/3 tongue, salivation, swallowing
Lesion:
- hypersensitive carotid sinus reflex
- loss if gag reflex (afferent)
Foramen: jugular foramen
X (vagus)
Function: phonation, swallowing, innervates viscera
Lesion:
- uvula deviates away from side of lesion
- loss of gag reflex (efferent)
Foramen: jugular foramen
XI (Accessory)
Function: Head & shoulder movement
Lesions:
- weakness turning head to CL side
Foramen: jugular foramen
XII (hypoglossal)
Function: tongue movement
Lesion: tongue deviaets towards side of lesion
Foramen: hypoglossal canal
Radial nerve
Posterior cord of the brachial plexus (C5-T1)
Motor main nerve: triceps, brachioradialis, extensor carpi radialis
Motor posterior interosseous branch: supinator, extentensor carpi ulnaris/digitorium/indicis/digiti minimi.pollicis longus and brevis/abductor polllicis longus
Sensory: proximal phalanges on dorsum hand thumb - 1/2 ring finger
Axillary damage - parlalysis of triceps - instability of shoulder, loss of elbow extension, wrist drop (unable to extend)
Saturday night palsy
Compression of radial nerve at humeral shaft –> unable to extend wrist/wrist drop
