Intrinsic Eye Muscles Flashcards
what are the intrinsic eye muscles? where are they found? what is it innervated by?
what can pathology of innervation of intrinsic eye muscles lead to?
pupillary abnormalities
what is the pupilarry reaction to light? what is this innervated by?
dilation is sympathetic
constriction is parasympathetc
what is the edinger-Westephal nucleus? what role does it play in the pathway of light reflex?
optic nerve -> optic chiasm -> optic tract ->EWN of both sides
its one of the sub parts of the third nerve nuclei.
some of these fibres go to the EWN of the opposite side and this explains why we have bilateral constriction of the pupil/consensual light reflex when light is shone in one eye.
efferent limb is via the CN III (oculomotor nerve) whcih causes pupillary constriction
what are some pupil abnormalities? what do they present as?
what are common vcauses of absent/abnormal pupilarry reflex?
in CN III palsy due to medical cause like diabetes, what should you do?
usually there is no damage to parasympathetic fibres - so check cupillary reflex on someone with CN III palsy
what happens is someone with a mediacl CN III palsy has pupillary damage? what should you do? what should you suspect?
if reflex is absent then suspect cerebral artery aneurysm
this is a medical emergency
what type of nerve is the CN III?
Efferent limb
what diseases affect the pupilarry reactions?
optic neuritis
severe glaucoma causing damage to optic nerve
retinal detachment
retinal infection
what are the clinical signs for Horner’s syndrome?
ptosis (drooping of eyelid)
miosis (excessive constriction of pupil)
anhidrosis (loss of sweating on affected side)
what is Horner’s syndrome?
anisocoria due to damage to the sympathetic innervation of the pupil
anisocoria = different sizes of pupil
give an example of how horner’s syndrome can occur
can occur due to distruption at any point
especially at superior cervical ganglia froma pancoast tumour of lungs
how do post ganglionic sympathetic fibres innervate the eye?
they travel via blood vessels to reach eye
