Cranial nerve Examination Flashcards
(30 cards)
What are the cranial nerves
12 pairs of nerves that emerge from brainstem and supply head and neck
sensory, motor and parasympathetic activity
Numbered 1-12
CN abnormalities
Cranial nerve abnormalities may arise from lesions affecting the;
- communicating pathways to and from the cortex, cerebellum and other parts of the brain stem
- nerve nucleus
- nerve
- neuromuscular junction disorders
- Muscle
Mnemonic for cranial nerves
Oh oh oh to touch and feel Virgin girls vagina and hymen
some say marry money but my brother says big brains matter most
Olfactory
Sensory
smell
tract: olfactory cells of nasal mucosa –> olfactory bulbs –> pyriform cortex
Optic nerve
Sensory
Vision
Tract: retinal ganglion cells –> optic chasm –> thalamus –> primary visual cortex in occipital lobe
Muscles of the eye
Superior, inferior, medial and lateral rectus muscles
superior and inferior oblique
Which cranial nerves innervate the eye muscles
Oculomotor, trochlear Abducens
Oculomotor innerveates which muscles
all apart from lateral rectus and superior oblique
Oculomotor
Motor function - innervates muscles and upper eyelet
parasympathetic function - constrict the pupils
3rd nerve palsy
lateral rectus - laterally
superior oblique - down
Down and out + ptosis (parasympathetic innervation)
Medical 3rd nerve palsy
pupil sparing
microvascular change on uncles or 3rd nerve pathway
Surgical 3rd nerve palsy
pupillary dilation
parasympathetic fibres run on outside of oculomotor nerves
something that presses on the nerve ( causes the pupil to dilate)
Trochlear nerve innervates
Superior oblique muscles
Trochlear nerve
motor
moves the eyeball
nucleus location: midbrain
depresses the adducted eye and intorts the abducted eye
longest intracranial course are II and IV are only nerves to decussate to contralateral side
Trochlear nerve lesions (4th nerve palsy)
Double vision when eye looking down (superior oblique moves the eye down)
When looking down at the paper or looking down the stairs
abducens Nerve
motor
eyeball movement
nucleus: pons
Structure innervated : lateral rectus
6th nerve palsy
horizontal double vision that is corrected in the primary position
Causes of 6th nerve palsy
Vasculitis ( DM and HTN) Raised ICP (due to turning junction)
Causes of 4th nerve palsy
- vasculitis (HTN and DM)
- tumour
- trauma
- congenital
superior oblique
3rd nerve palsy causes
Vasculitis (HTN and DM)
Aneurysm (berry aneurysm of circle of wills)
Internuclear ophthalmoplegia
disorder of conjugate gaze
-failure of adduction of affected eye with nystagmus on lateral gaze in contralateral eye
Can be unilateral or bilateral
Results from lesion of medial longitudinal fasiculus (connects 3rd and 6th nerve nuclei)
Commonly seen in multiple sclerosis
Horner syndrome
consists of:
- ptosis (drooping of the eyelid)
- miosis (constriction of the pupil)
- enopthlamosis (posterior displacement of the eyeball shruken)
- anhidorsis (not able to sweat properly)
From ipsilateral disruption of cervical/thoracic sympathetic chain
Trigeminal nerve
sensory input from face
nucleus: Pons and medulla
structure innervated: face (ophthalmic, mandibular and maxillary division) and touch pain pressureto anterior 2/3rds of the tongue
Motor Mastication nucleus location: pons Structure innervated: Muscles of mastication (master, temporalis, medial and lateral pterygoids
Herpes zoster opthalmicus
pain may priced vesicles lifetime risk 1% V2/v3 rarely affected elderly and immunocompromised treated with oral acyclovir
