Anatomy of eye reflexes

Question 1

What is a possible mechanism for causing diplopia in orbital trauma?

Answer 1

Damage to the suspensory ligament

Question 2

How might a fracture to the maxilla/zygoma cause altered sensation to the facial skin?

Answer 2

Damage to the infraorbital NVB within the infraorbital canal (containing the infraorbital nerve, a branch of maxillary nerve V2)

Question 3

Which large branch of the opthalmic nerve (V1) covers a large area of the forehead?

Answer 3

Supraorbital nerve

Question 4

What is the angle of the mandible supplied by?

Answer 4

C2/C3 spinal nerves

Question 5

How are the afferent and efferent limbs of the corneal reflex transmitted?

Answer 5

Afferent- V1 (opthalmic nerve) to trigeminal ganglion, then to trigeminal nerve (CNV), then to pons
Efferent- central connections within the CNS between CN V and the facial nerve ( CN VII), transmitted by CN VII to orbicularis oculi

Question 6

Where do presynaptic sympathetic axons to the head and neck organs…

a) exit the spine
b) synapse
c) exit the sympathetic chain

Answer 6

a) T1 vertebral level
b) ascend within the sympathetic chain and synapse within the superior cervical sympathetic ganglion
c) join the internal and external carotid nerves coursing along the surface of the internal and external carotid arteries

Question 7

How do sympathetic axons enter the orbit?

Answer 7

Along the opthalmic artery, a branch of the internal carotid

Question 8

What is the stellate ganglion?

Answer 8

Fusion of the inferior cervical and first thoracic sympathetic ganglia

Question 9

Which cranial nerves are responsible for parasympathetic supply to the head and neck organs?

Answer 9

Oculomotor
Facial
Glossopharyngeal
Vagus

Question 10

How do parasympathetic axons reach the orbit and lacrimal gland?

Answer 10

CN III- to the eye (via the ciliary ganglion in the orbit)

CN VII- to the lacrimal gland via it’s parasympathetic ganglion within the head

Question 11

How does the occulomotor nerve exit the base of skull?

Answer 11

Superior orbital fissure

Question 12

Where does the occulomotor nerve connect with the CNS?

Answer 12

In the midline at the junction between pons and midbrain

Question 13

What muscles does the superior branch of the occulomotor nerve supply?

Answer 13

Levator palpebrae superioris
Superior rectus
(all others supplied by the inferior branch))

Question 14

Which ciliary nerve (long or short contains) somatic sensory axons which function in the first part of the afferent limb of the corneal reflex?

Answer 14

Long ciliary nerve

Question 15

The ciliary nerves supply autonomic axons to the orbit. What do these autonomic axons control?

Answer 15

Diameter of the iris/pupil and refractive shape of the lens

Question 16

Which muscle controls elevation of the eyelid in a sympathetic response?

Answer 16

Levator palpebrae superioris, via it’s smooth muscle

Question 17

What is the response of the pupil to sympathetic stimulation?

Answer 17

Mydriasis

Question 18

Which muscles control the dilatation of the pupil?

Answer 18

Dilator pupillae muscles

Question 19

How would the pupil appear in CNIII palsy?

Answer 19

Fixed-dilated due to lack of constriction from parasympathetic axons in the ciliary nerves

Question 20

Which muscles control pupillary constriction?

Answer 20

Sphincter pupillae

Question 21

What are the two midbrain nuclei involved in the pupillary light reflexes?

Answer 21

Pretectal

Edinger-Westphal

Question 22

What are the three components of the accommodation reflex? Which nerve is responsible for this?

Answer 22

1. Pupillary constriction
2. Bilateral convergence
3. Biltaeral relaxation of the lens (becomes shorter and fatter)

Oculomotor nerve

Question 23

What are the afferent and efferent limbs of the reflex tear pathway?

Answer 23

Afferent- corneal/conjunctival stimulation. V1

Efferent- parasympathetic axons from VII