Ocular Reflexes Flashcards
what is a reflex?
stereotypical predictable response to a stimuli
what is the path of the reflex arch?
afferent limb —–> synapse —–> efferent limb
what is the corneal blink reflex stimuli?
touch or irritation to cornea
what is the afferent limb of the corneal blink reflex?
ophthalmic division of the trigeminal (V1)
what is the efferent limb of the corneal blink reflex?
facial nerve (CN VII) bilateral response
what happens if either the sensory or motor limb is damaged?
corneal relfex is absent
what is the stimulus, afferent limb and efferent limb of the pupillary light reflex?
- light striking retina
- CN II
- CN III
the response is that both pupils constrict even though light is only shining on one eye
what is the pathway for the pupillary light reflex?
- optic nerve fibers bypass the LGN and project to the pretectal midbrain
- neurons from pretectum project to bilateral E-W nuclei
- neurons in each E-W nuclei project to ipsilateral ciliary ganglion
what is the accommodation reflex/near reflex?
shifting of the gaze from distant to near object causing three things happen
what are the three things that happen during an accommodation reflex?
- convergence of the eyes
- accommodation of lens
- pupillary constriction
entire accommodation reflex is lost when what happens?
CN III lesion
Pupillary control parasympathetics includes?
constrictor muscles
E.W. nucleus (CN III)
ciliary ganglion
Pupillary control sympathetics includes?
dilator muscles
superior cervical ganglion
hitchhikes on internal carotid artery
