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