Cranial Nerve Disorders Flashcards
what are the 4 functions of cranial nerves?
special sensory, general sensory, motor activity and autonomic functions
what are the special senses and their nerves?`
olfaction (I), vision (II), taste (VII, IX), hearing and balance (VIII)
what are the general sensation of the cranial nerves?
mainly the Vth which supplies sensation of the face in 3 branches
what is the parasympathetic innervation of the cranial nerves?
pupillary constriction= III, lacrimation= VII, salivation= VII (submandibular and sublingual glands) and IX (parotid glands), vagal input to organs in the thorax and abdomen
what is the motor activity of the cranial nerves?
eye muscles- III, IV and VI (LR6, SO4, rest 3), muscles of mastication- V, muscles of facial expression- VII, muscles of larynx and pharynx= mainly X, sternocleidomastoid and trapezius muscles= XI
what are the cranial nerve reflexes?
pupillary light reaction, corneal reflex, jaw jerk, gag reflex
what nerves are involved in the pupillary light reaction?
afferent= II and efferent= III
what are the nerves involved in the corneal reflex?
afferent= V and efferent= VII
what are the nerves involved in the jaw jerk?
afferent and efferent= V
what are the nerves involved in the gag reflex?
afferent= IX and efferent= X
what are the locations of the cranial nerve nuclei?
III and IV nuclei lie in the midbrain, V, VI and VII lie in the pons, VIII lies at the pontomedullary junction, IX, X, XI and XII lie in the medulla
what causes a fixed dilated pupil?
loss of parasympathetic input eg complete 3rd nerve palsy
what causes a constricted pupil?
damage anywhere within the sympathetic pathway
what is dysarthria?
disorder articulation or slurring of speech
what is dysphagia?
difficulty swallowing
what is pseudobulbar palsy?
bilateral UMN lesions eg in vascular lesions of both internal capsules, MND- dysarthria, dysphagia, spastic, immobile tongue, brisk jaw jerk and gag reflex
what is bulbar palsy?
bilateral LMN lesions affecting IX- XII eg MND, polio, tumours, vascular lesions of the medulla and syphilis - wasted, fasciculating tongue, dysarthria, dysphagia
what is vestibular neuronitis?
sudden onset, disabling vertigo, vomiting, gradual recovery, causes is uncertain but thought to be viral
what is Bell’s palsy?
idiopathic facial nerve palsy, unilateral facial weakness, LMN, often preceded by pain behind the ear, eye closure affected, treated with steroids
what is trigeminal neuralgia?
paroxysmal attacks of lancinating pain, triggers= chewing, speaking or cold air, treated with carbamazepine
how do we determine between an UMN vs LMN facial nerve palsy?
UMN lesion the forehead will be spared and the patient will be able to move their forehead on the affected side but in a LMN lesion the forehead will not be spared and the patient cannot move their forehead on the affected side
what does a IIIn palsy look like?
ptosis (drooping eyelid), dilated, non-reactive pupil, divergent strabismus (squint)= down and out position of affected eye
what are the triad of symptoms caused by Horner’s syndrome?
ptosis, miosis and anhidrosis (loss of sweating)
what causes Horner’s syndrome?
damage to the sympathetic nervous system supplying the face
what nerve would be affected if the eye does not close?
the facial nerve as the obicularis oculi closes the eyelid
what does a VIn palsy look like?
affected eye points towards the nose= away from the direction of the paralysed muscle
