Vision 2 Flashcards
what is another name for extrinsic eye muscles ?
extra ocular muscles
from which ring do the rectus muscles arise from?
annular fibrous ring at the apex of the orbit
which extrinsic muscle arises from anterior of the orbit?
inferior oblique muscle
which muscle elevates the superior eye lid?
LPS - levator palpebrae superioris
where abouts do the oblique muscles insert on the sclera?
posteriorly
what nerve innervates the lateral rectus ?
abducens (VI)
what nerve innervates the superior oblique?
trochlear (IV)
what nerve innervates the medial rectus ?
oculomotor (III)
what nerve innervates the inferior rectus ?
oculomotor (III)
what are the three action of superior oblique?
depress
intortion
abduction
what are the three action of inferior oblique?
elevate
extortion
abduction
what does strabismus mean?
squint
what are the two types of squints called ?
- convergent
- divergent
Esotropia (manifest convergent squint)
Exotropia (manifest divergent squint)
what are the two functional consequences of a squint?
amblyopia
diplopia
what is amblyopia ?
brain supresses the image of one eye leading to poor vision in that eye without any pathology
what is diplopia ?
double vision
what is your visual field?
everything you can see with one eye including in the periphery
are images of objects reflected upside down and inverted on your retina?
yes
what happens when there is a lesion on the Right Optic nerve ?
blindness in right eye
what happens when there is a lesion on the Optic chiasma ?
bitemporal hemianopia
- vision has been cut laterally
what happens when there is a lesion on the Right Optic tract ?
contralateral homonymous hemianopia
- both eyes have blindness in the left hemi side
what is the reflex when both pupils constrict at the same time?
consensual reflex
describe the pathway of the efferent limb of the light reflex
- efferent fibres radiate from the EWN
- preganglionic parasympathetic fibres pass through IIIn into the orbit
- the fibres synapse in the ciliary ganglion
- post ganglionic fibres go through short ciliary nerves to constrictor pupillae
what is anisocoria ?
pupils which are different sizes
what condition could causes anisocoria?
horners syndrome
what are the three main causes of the pupillary reflex being absent?
- disease of the retina
- disease of the optic nerve
- disease of the III cranial nerve
does sympathetic dilate or constrict the pupil?
dilate
where do the sympathetic fibers travel next to in the head and neck?
travel along with blood vessels
