Ocular muscles

Question 1

What are the seven extraocular muscles

Answer 1

1. ) Lateral rectus
2. ) Medial rectus
3. ) Superior rectus
4. ) Inferior rectus
5. ) Superior oblique
6. ) Inferior oblique
7. ) Levator palpebrae superioris

Question 2

Which muscles correct the eye movements

Answer 2

Superior oblique and inferior oblique

Question 3

Which muscle lifts the upper eye lid

Answer 3

Levator palpebrae superioris

Question 4

L.O.S insertion

Answer 4

• It inserts onto the upper eye li

Question 5

LPS nerve supply

Answer 5

Facial nerve (sympathetic nerve supply)

Question 6

What is it called when you get loss of function of LPS

Answer 6

Ptosis

Question 7

What does the lateral rectus do

Answer 7

Pulls the eye laterally (abduction)

Question 8

What does the medial rectus do

Answer 8

Pulls the eye medially (adduction)

Question 9

What does the superior rectus do

Answer 9

Pulls the eye up + medially and rotates it

Question 10

What does the inferior rectus do?

Answer 10

Pulls the eye down and medially rotate it

Question 11

Define intorsion

Answer 11

Rotation of the eye

Question 12

Define extorsion

Answer 12

Rotation of both eyes

Question 13

What does superior oblique

Answer 13

Corrects the inferior rectus action. The tendon goes through a trochlear (Pulley) and attaches to the globe of the eyeball at the top

Question 14

What does superior oblique

Answer 14

Corrects the inferior rectus action. The tendon goes through a trochlear (Pulley) and attaches to the globe of the eyeball at the top

Question 15

What does the inferior oblique do

Answer 15

Corrects the superior rectus action

Question 16

How to examine eye movements

Answer 16

1. ) Sit directly in front of patient (so eyes at same level)
2. ) Sit 2 arms lengths apart
3. ) Test peripheral vision

Question 17

How to examine lateral and medial rectus

Answer 17

• Sit in front of the patient.
• Place a finger at eye level about an arms length from their face and move your finger right and left.
• Do this twice, once whilst observing the left eye and once whilst observing the right eye.

Question 18

How to test superior and inferior rectus muscle

Answer 18

Sit in front of the patient. Place a finger at eye level about an arms length from their face and out to the right side move your finger up and down.
Repeat this on the left side.

Question 19

The issue

Answer 19

• If the lateral rectus muscle doesn’t work the eye can’t be abducted
• Superior + inferior can’t be tested in isolation

Question 20

Examination of inferior and superior oblique muscles

Answer 20

• We have to position the eye so that superior/inferior recti are giving max rotation + look for complete correction

Question 21

Examination of inferior and superior oblique muscles

Answer 21

• We have to position the eye so that superior/inferior recti are giving max rotation + look for complete correction
• Sit in front of the patient. Place a finger at eye level about an arms length from their face and out to the left side move your finger up and down.
  Repeat this on the right side.

Question 22

Semi-circular canal structure

Answer 22

Have:

1. ) Superior canal
2. ) Lateral Canal
3. ) Posterior canal
4. ) Vestibule
5. ) Cochlea

Question 23

Where does the semi-circular canallie

Answer 23

The petrous part of temporal bone

Question 24

Semi-circular canal function

Answer 24

• Has an ampulla (a swelling)

- In this ampulla there is cupula/hair cells and nerve fibres

Question 25

Function

Answer 25

• The cupula movement generates nerve impulses

- Has cilia

Question 26

Process

Answer 26

• endolymph fluid moves
• cupula distorts
• distortion detected by hair cells
• neuronal impulse generates

Question 27

Dizziness

Answer 27

• When the semi-circular canals send signals to brain when there is no movement

Question 28

Physiological cause of dizziness

Answer 28

After spinning round

Question 29

Pathological cause of dizziness

Answer 29

Labyrinthitis: inflammation of hair cells (often due to viral infection)

Question 30

Reflex

Answer 30

• ice cold water in ear
• petrous part of bone is cold
• part is warm
• creates a convection current in canal
• signal to brain is sent
• eyes slowly move towards cold water then jump back to normal position