C: Accomodation Reflex

Question 1

What are the 3 components of the accomodation reflex - which muscle does each?

Answer 1

1) Pupils constrict - sphincter pupillae
2) Ocular convergence medial rectus
3) Lens rounding - contraction ciliary muscle

Question 2

Which CN carries the afferent limb of the accomodation reflex and which the efferent?

Answer 2

Afferent = CN1
Efferent = CN2

Question 3

In the accommodation reflex is the striate cortex involved?

Answer 3

Yes - afferent part ends here and gives rise to interneuron which synpases with first neuron in efferent part of the reflex

Question 4

In the accomodation reflex fibres from the striate cortex synapse where?

Answer 4

In the somatic occulomotor nucleus

In the Edinger Westphal (PS) occulomotor nucleus

Question 5

What happens in the somatic occulomotor nucleus in the accomodation reflex?

Answer 5

Fibres from striate cortex synapse with fibres which travel to medial rectus via CN3

Question 6

What happens in the Edinger Westphal nucleus in the accomodation reflex?

Answer 6

Fibres from the striate cortex synapse with preganglionic PS fibres which travel to ciliary ganglion via CN3

Question 7

Which autonomic ganglion of the head is involved in the accomodation reflex?

Answer 7

Ciliary ganglion

Question 8

What is the nerve supply to sphincter pupillae and ciliary muscle in the accomodation reflex?

Answer 8

Post ganglionic PS fibres carried from ciliary ganglion