Lecture 7: Eye And Adnexa

Question 0

Oculomotor nerve innervates what muscles

Answer 0

Supplies all muscles of the eye except superior oblique and lateral rectus

• medial rectus
• inferior oblique
• superior rectus
• inferior rectus
• levator palpebrae superioris

Question 1

Ciliary ganglion

Answer 1

Parasympathetic ganglion for post- synaptic fibres to ciliary muscle and sphincter pupillae

Question 2

Oculomotor nerve exits where

Answer 2

• Cell bodies in midbrain.
• Exits cranium via superior orbital fissure.

• Efferent motor fibres to medial/superior/inferior rectus
muscles, inferior oblique, levator palpebrae superioris

• Parasympathetic motor fibres to sphincter pupillae (via ciliary ganglion).

Question 3

Abducens nerve exits where

Answer 3

• Cell bodies in pons.
• Emerge from brainstem at junction of pons and medulla.
• Enters orbit via superior orbital fissure.
• Pure motor nerve (efferent fibres to lateral rectus).

Question 4

Superior oblique muscle- trochlear

Function?

Answer 4

Abducts, depresses and medically rotates the eyeball

Question 5

Inferior oblique muscle- oculomotor

Function?

Answer 5

Abducts, elevates and laterally rotates the eyeball

Question 6

Superior rectus- oculomotor

Function?

Answer 6

Elevates, adducts and medially rotates the eyeball

Question 7

Inferior rectus- oculomotor

Function?

Answer 7

Depresses, adducts and laterally rotates the eyeball

Question 8

Medial rectus- oculomotor

Function?

Answer 8

Adducts the eyeball

Question 9

Lateral rectus- abducens

Function?

Answer 9

Abducts the eyeball

Question 10

Upper eyelid is comprised of what?

Answer 10

Upper: Orbicularis oculi + Levator palpebrae superioris +

superior tarsal smooth muscle

Question 11

What muscles are used to open and close the eyelid

Answer 11

• To close eyelids: orbicularis oculi contracts and levator palpebrae superioris relaxes.
• To open eyelids: levator palpebrae superioris contracts.

Question 12

To open eyelid in fright

Answer 12

• Open eyelids wide in fright = Superior tarsus muscle =

smooth muscle under sympathetic control.

Question 13

Tarsal glands and ciliary glands

Answer 13

• Tarsal glands: secrete oily substance into tears.

* Ciliary glands: modified sweat glands.

Question 14

Ptosis in horners syndrome

Answer 14

Drooping of superior eyelid, caused by loss of sympathetic Innervation to superior tarsus muscle ( opens eyelid wide in fright)

Question 15

Blood supply of the eye

Answer 15

Opthalmic artery branching from the Internal carotid

Question 16

Parasympathetic innervation of lacrimal gland

Sympathetic Innervation of the lacrimal gland

Answer 16

From facial nerve, synapses at the pterygopalatine ganglion and again right on the lacrimal gland to create tears.

Sympathetic and sensory fibres do not synapses in the pterygopalatine ganglion, they travel through

Question 17

Development

Answer 17

• Surface ectoderm => lens, cornea, conjunctiva, eyelashes,
lacrimal glands.

• Mesenchyme => choroid, sclera, tarsal plates, orbicularis oculi.

Question 18

Hyaloid canal

Answer 18

Hyaloid artery supplies developing lens and then regresses at 10
weeks development to form hyaloid canal.

Question 19

Vision

Answer 19

Rods = dim-light, peripheral
vision receptors

Cones = bright light, high-acuity
colour receptors

Question 20

Eyeball

Answer 20

Optic disc: blind spot, where retinal ganglion cell nerve axons leave retina in optic nerve and pass to brain.

Fovea centralis: area of macula with most acute vision, only cones.

Question 21

Tunica of the eye

Answer 21

• Fibrous (outer): Sclera (white), cornea (clear)
• Vascular pigmented: choroid*, ciliary body, iris
• Nervous coat (inner): retina

Question 22

Are the sclera and cornea vascular or avascular?

Answer 22

Both avascular

Question 23

Corneal reflex ( when someone pokes you in the eye)

Answer 23

Ophthalmic nerve (CNV1) provides sensory innervation to cornea.

• Facial nerve provides motor innervation to orbicularis oculi of BOTH eyes.

Question 24

Accomodation reflex of the eye- sympathetic

Answer 24

In the absence of nerve stimulation the ciliary muscle is relaxed.
Zonular fibres are under tension
Lens is stretched thin the refract light for distance vision

Question 25

Accommodation reflex for the eye- parasympathetic

Answer 25

Ciliary muscles are contracted
Zonular fibres are relaxed
In the absence of stretching the lens becomes more spherical (thick) to accommodate for near vision

Question 26

Miosis: Horner’s Syndrome

Answer 26

Pupillary constriction of affected side due to paralysis of pupillary dilator smooth muscle (innervated by sympathetic nerves).

• Loss of sympathetic tone => parasympathetic effects!

Question 27

Retinal ganglion cells project where for pupillary light reflex?

Answer 27

Lateral geniculate body of the thalamus

Question 28

Pupillary light reflex
After retinal ganglion cells arrive at the lateral geniculate body, Interneuron projects from superior colliculus bilaterally to?

Answer 28

Edinger-Westphal nuclei

Question 29

Pupillary light reflex

Preganglionic parasympathetic fibres leave Edinger-Westphal nuclei in the oculomotor nerve (CN III) which synapses?

Answer 29

in the ciliary ganglion

Question 30

Pupillary light reflex

Postsynaptic parasympathetic fibres synapse on smooth muscle (sphincter pupillae) and cause?

Answer 30

bilateral constriction of pupils

Question 31

What are three intrinsic muscles of the eye?

Answer 31

Dilator pupillae
Sphincter pupillae
Ciliary muscles

Question 32

Sympathetic fibres from superior cervical ganglion to lacrimal gland via pterygopalatine ganglion does what?

Answer 32

Inhibits tears

Question 33

Parasympathetic fibres from facial nerve to lacrimal glands via pterygopalatine ganglion does what?

Answer 33

Causes tears

Question 34

Sympathetic fibres from superior cervical ganglion to dilator pupillae via ciliary ganglion does what?

Answer 34

Dilates pupil