Session 8- Extraocular eye muscles, actions and testing

Question 1

what does binocular vision allow

Answer 1

wider field of vision and depth perception

Question 2

what is conjugate eye movement

Answer 2

eyes need to coordinate and move together

Question 3

what causes diplopia

Answer 3

misalignment of two visual axes image focuses on different area of each retina
-brain unable to fuse these see 2 separate images

Question 4

what is diplopia

Answer 4

double vision

2 images seen can be displaced horizontal, vertical and diagonally

Question 5

what are the for recti

Answer 5

superior
inferior
lateral
medial

Question 6

what are the 2 obliques

Answer 6

superior

inferior

Question 7

where do extra-ocular muscle attach

Answer 7

sclera

Question 8

where do extraocular muscles riginate

Answer 8

apex of orbit except inferior oblique which arises from the floor of orbital cavity anteriorly
-the 4 recti originate from a common tendinous ring

Question 9

what innervates the extra ocular muscles

Answer 9

LR6SO4

Lateral rectus- 6- abducens
Superior oblique- 4 -Trochlear

all remaining occulolotor

Question 10

why do some muscles attach at an oblique angle

Answer 10

the muscles run in line with the axis of orbit

-confers several actions of movement on globe for some of the extra ocular muscles

Question 11

which muscles have a single action on the eye

Answer 11

Medial rectus and lateral rectus

Question 12

what movement is moving the eye medially

Answer 12

adduction

Question 13

what movement is moving the eye laterally

Answer 13

abduction

Question 14

what muscles adducts the eye

Answer 14

medial rectus

Question 15

what muscle abducts the eye

Answer 15

lateral rectus

Question 16

what is the action of superior rectus if starting from primary resting gaze

Answer 16

elevate
slightly adducts
slightly intorts

Question 17

when is the superior rectus a more powerful elevator

Answer 17

when the eye is positioned laterally

Question 18

where does superior rectus inserts

Answer 18

superior anteriolateral surface

Question 19

where does IR attach

Answer 19

anteroinferior surface of globe

Question 20

action of IR

Answer 20

depress
slightly adducts
slightly extort

Question 21

when is IR a more powerful depressor

Answer 21

when the eye is positioned laterally

Question 22

where does SO attach

Answer 22

passes through trochlea inserts into superior-posterior aspect of globe

Question 23

SO action

Answer 23

intort

depress

Question 24

when is the SO a more powerful depressor

Answer 24

when eye is positioned medially

Question 25

where does IO attach

Answer 25

infero-posterior aspect of globe

Question 26

action of IO

Answer 26

extort elevate slightly abduct

Question 27

when is IO a more powerful elevator

Answer 27

when eye is positioned medially

Question 28

which extra-ocular muscles have an action in elevating the eyeball

Answer 28

superior rectus | inferior oblique

Question 29

which extra-ocular muscles have an action in depressing the eye ball

Answer 29

inferior rectus | superior oblique

Question 30

which extra ocular muscles are stronger elevators and depressors of th eyeball when the eye is adducted

Answer 30

inferior oblique | superior obliquw

Question 31

which extra-ocular muscles are stronger elevators and depressors of the eyeball when the eye is abducted oosition

Answer 31

superior and inferior rectus

Question 32

strabismus

Answer 32

common in children - exact cause not always known in adults- acquired due to pathology or disease -myasthenia gravis/ nerves supplying the muscles cranial nerves can be affected - vasculopathic - physical compression - raised intracranial pressure

Question 33

how do we isolate elevaton and depression actions of SR/IO and IR/SO

Answer 33

move starting postion of eye laterally or medially first then test elevation and depression

Question 34

what are the main elevators and depressors of the eye when the eyball is starting from the lateral position

Answer 34

recti muscles superior - elevates inferior- depreses

Question 35

what muscles are the main elevators and depressors of the eye when the eye is in the medial position

Answer 35

IO - elevates | SO- depresses

Question 36

what are the 2 qcquired causes of CN III palsy

Answer 36

vasculopathic lesions- pupil spared | compressive lesions -pupil involved

Question 37

which extra ocular muscles does the trochlear nerve innervate

Answer 37

superior oblique muscle | -intorts, abducts and depresses

Question 38

in what position is the eye held in a trochlear nerve lesion

Answer 38

extorted, slightly elevated and adducted

Question 39

how is the extortion of the eye compensated in a trochlear nerve palsy

Answer 39

head tilt- this is because the eye is extorted and slightly elevated

Question 40

what is the most likely cause for CN III, IV and VI

Answer 40

vasculopathic

Question 41

What is the difference between periorbital cellulitis and orbital cellulitis?

Answer 41

Periorbital cellulitis confined to tissues superficial to orbital septum and tarsal plates. Orbital cellulitis - result of an infection affecting fat and muscles posterior to orbital septum, within the orbit but not involving the globe.

Question 42

What are the three main types of conjunctivitis?

Answer 42

bacterial viral allergic

Question 43

What is age-related macular degeneration?

Answer 43

Most common cause of blindness in the UK. Degeneration of the macula is the key feature with changes usually bilateral. Two forms of macular degeneration are dry and wet

Question 44

What features will you see on the retina for central retinal artery occlusion?

Answer 44

Pale | retina, cherry red spot

Question 45

Which test do you use to check colour vision?

Answer 45

ishihara chart

Question 46

what is used to test visual acuoty

Answer 46

snellen chart

Question 47

What is orbital cellulitis

Answer 47

red and swollen right upper and lower eyelids. On examination, he had reduced visual acuity, mild proptosis, painful and reduced ocular movements. (usually caused by upper respiratory tract infection from the sinuses)