Examinations

Question 1

Functions of the direct pupil reflex (3)

Answer 1

Adjust amount of light reaching retina
Depth of field of eye
Protects photoreceptors

Question 2

Action of sphincter muscles fibres

Answer 2

Contract, constricting the pupils

Question 3

What nervous system are the sphincter muscle fibres controlled by?

Answer 3

Parasympathetic NS

Question 4

Action of dilator mm

Answer 4

Contract - dilating the pupils

Question 5

What nervous system are the dilator mm fibres controlled by?

Answer 5

Sympathetic NS

Question 6

What causes the red reflex?

Answer 6

Light reflecting back from vascularised retina

Question 7

What is leukorcoria ?

Answer 7

White reflex

Question 8

Causes of leukocoria in children? (2)

Answer 8

Retinoblastoma

Retinal detachment

Question 9

What is visual acuity?

Answer 9

The clarity of vision/ability of eye to resolve detail

Question 10

What is the accommodation response

Answer 10

When eyes are directed from a distance (>30ft away) to an object nearby

Question 11

Is the accommodation response consensual?

Answer 11

Yes

Question 12

What are the 3 actions in the accommodation response?

Answer 12

Pupil accommodation
Lens accommodation
Convergence accommodation

Question 13

What occurs in lens accommodation (3)

Answer 13

Incr curvature
Incr refractive power
Convergence accommodation

Question 14

What happens in convergence accommodation

Answer 14

Direct nasally

Contraction of medial rectus + relaxation of lateral rectus

Question 15

Light reflex neural circuit

Answer 15

Light shone R eye only

• -> retina
• -> CN II
• -> Optic chiasm
• -> Optic tract
• -> Brachium of superior collliculus
• -> AP reach R + L pretectal fibres midbrain
• -> Stimulates R + L side EW nucleus
• -> Cont parasymp preganglion fibres
• -> Gens AP by sending axons through CN III
• -> Iris sphincter –> pupil constriction

Question 16

Dark reflex neural circuit

Answer 16

Retina –> OT –>
==> Terminates on neuron sin hypothalamus
–> Descends to SC to end on
–> Symp preganglion neurons lat horns T1-3
–> Sends axons out of SC to symp neurons in superior cervical ganglion
–> Symp post ganglion axons in long ciliary nn
–> iris dilation

Question 17

Afferent limb accom response (3)

Answer 17

Retina )+ optic nn /tract
LGB (+ axons optic radiation)
Visual cortex

Question 18

Ocular motor control neurons (2)

Answer 18

Visual associate cortex

Suproculomotor nuclei

Question 19

Role visual associate cortex

Answer 19

Determines if image = out of focus

+ sends corrective signals via int capsule + crus cerebri to suprooculormotor nuclei

Question 20

Role suprooculomotor nuclei

Answer 20

Generates motor signals that initiate accom response

Question 21

What are the 2 components of the efferent limb of the accom response

Answer 21

EW nucleus

Oculomotor neurons

Question 22

Role EW nucleus in eff limb accom response

Answer 22

Sends axons to CN III - control ciliary ganglion

–> short ciliary nn –> controls iris sphincter + ciliary mm

Question 23

Role Oculomontor neurons in in eff limb accom response

Answer 23

Sends axons to CNIII

- controls medial rectus to converge eyes