Cranial nerves Flashcards
How many extraoccular muscles are there? name them and the nerves which innovate them
6 4 rectus muscles superior, medial, inferior (oculomotor) Lateral (abducens) 2 oblique muscles Superior (trochlear) Inferior (oculomotor)
What is the origin and attachment of the rectus muscles?
Origin- common tendinouse ring
Attachment- sclera
Where do the oblique muscles attach?
Behind the equator
What does the suprior oblique muscle hook around?
fibrocartilaginous pulley (trochlear)
What is the action of the superior and inferior oblique muscle?
Superior- Down and intorsion (inward rotation)
Inferior- up and extorsion (outward rotation)
What Is the parasympathetic nervous pathway of the oculormotor nerve?
Pre-synaptic fibers travel to the ciliary ganglion
Post-synaptic fibers innervate the sphincter pupillae and ciliary muscles
What is the sympathetic innervation to the eye?
Sympathetic fibres go from the carotid plexus to the dilator pupillae blood vessels of the eye
What is the primary action of the medial, lateral, inferior and superior rectus muscles?
Medial- adduction
lateral- abduction
Superior- elevate
inferior- depress
What are the symptoms of an oculomotor palsy?
ptosis (lev palpebrae) Stabismus (eyes not aligned) Dyplopia (double vision) Dilated pupil Down and out due to the unapposed action of superior oblique (down) out (lateral rectus)
What cause cause an oculomotor palsy?
Ischemic event from diabetes and hypertension
aneurysm at the junction of internal carotid and posterior communicating arteries
What are the is the cause and symptoms of a trochela pasly?
Paralysis of superior oblique
Hardest to diagnose but also rarest.
Patients attempt to minimise diplopia by tilting head away from paralyzed eye
Eyes move up and in
What is the cause and symptoms of an abducens pasly?
Paralysis of lateral rectus
Effected eye cannot abduct
Goes through cavernous sinus – abducens palsy can be a sign of raised intracranial pressure
What is the name of the intermediate facial nerve? What are the categories of its function?
nervus intermedius– special sensory, and parasympathetic
What are the muscles of facial expression?
post belly digastric, stylohyoid, stapedius
What is bells palsy? What is the potential cause?
Facial muscle paralysis LMN injury
swelling of nerve in facial canal
Explain the concept of for-head sparing
a patient with forehead sparing (i.e. no involvement to the occipitofrontalis muscle) will have a UMN origin to the palsy, due to the bilateral innervation of the forehead muscle).
UMN- stroke
LMN- bells palsy-forhead will crease
What are the symptoms of bells palsy? State the inhibited branch of the facial nerve causing each symptom
Droopy eye lid (can not close eyes), (temporal and zygomatic branches)
Facial paralysis
Hyperacusis (increased sensitivity to sound) (nerve to stapedius)
Metallic taste (chorda tympani)
Reduced lacrimation (greater petrosal nerve)
Droopy corner of the mouth
dry mouth
What are the branches of the vagus nerve in the neck?
Auricular nerve
external acoustic meatus and tympanic membrane
Pharyngeal nerves – pharyngeal plexus
muscles and mucous membranes
Superior laryngeal nerve –
sensory to laryngeal mucosa above vocal folds, motor to cricothyroideus
Right recurrent laryngeal nerve – loops under RSCA
sensory to mucosa below folds, motor to all intrinsic laryngeal muscles (excluding cricothyroideus)
Left recurrent larnygeal – loops under the aortic arch
What is the parasympathetic innervation to the intrinsic eye muscles?
Ocularmotor nerve, ciliary ganglion, opthalmic branch of trigeminal
What is the parasympathetic innervation to the lacrimal gland, nasal cavity, maxillary sinus ans palate?
Facial nerve
Pterygopalatine ganglion branch
maxillary trigeminal
What is the parasympathetic innervation to the submandibular and sublingual glands?
facial nerve
Submandibular ganglion
mandibular trigeminal
What is the parasympathetic innervation to the parotid gland?
glosso nerve
otic ganglion
mandibular trigeminal
List the nerves found in the …
3, 4, 5, 6
What is the consequnce of damage to the olfactory nerve?
Anosmia
What will be effected if the optic nerve is damaged?
Visual field defects
Pupillary light reflex issues
What will be effected if the trigeminal nerve is damaged?
Corneal blink reflex
Sensory innervation over opthalmic, maxillary and mandibular divisions
Loss of motor function
Jaw deviates to side of lesion
What will be effected if the Facial Nerve is damaged?
Lower Motor Neuron Lesion – ipsilateral facial weakness
- bells palsy
Upper Motor Neuron Lesion – contralateral facial weakness, forhead sparing, stroke
What will be effected if the Vestibulocochlear is damaged?
dolls eye- Vestibulo-ocular reflex
What will be effected if the vagus is damaged?
Vagus UMN unilateral damage- Minimal effect on swallowing – bilateral innervation
Vagus UMN bilateral damage
Paralysis of vocal folds
swallowing difficult
Vagus LMN unilateral damage
Palate drops, vocal fold paralysis, weak pharynx – difficulty swallowing
Vagus LMN bilateral damage
Usually not compatible with life
What can cause a Vagus UMN bilateral damage?
TIA- can effect this- casues aspiration neumonia
Symptoms of damage to midbrain
Ptosis (drooping of the upper eyelid)
Diplopia (double vision)
Dilated pupils
Inability to gaze up, down or inward
Symptoms of daWallenberg’s Syndrome) – ataxia, inability to swallow, hoarse voice)
mage to pons
Facial sensation loss CN 5
Corneal reflex loss CN IN5 OUT 7
Facial muscle drooping
Inability to gaze outwards (abduction)- CN 6
Symptoms of damage to medulla
Difficulty swallowing Loss of gag and cough reflex- TONGUE PERTRUSION , respiratory changes Vomiting Tongue protrusion (deviate towards) Respiratory pattern changes.
(Wallenberg’s Syndrome) – ataxia, inability to swallow, hoarse voice)
