Lecture 7: Eye And Adenxa

Question 1

Know how to label the picture on slide 4

Answer 1

Do it nigs

Question 2

Know the 6 muscles of the eye slide 7

Their innervation and muscle action

Answer 2

Superior rectus- oculomotor nerve, elevates, and laterally rotates the eyeball
Inferior rectus- CN 3- depresses, adducts, and rotates eyeball laterally
Lateral rectus- CN 6- abducts eyeball
Medial rectus- CN 3- adducts eyeball
Superior oblique- CN 4 (trochlear)- abducts, depresses, and medially rotates eyeball
Inferior oblique- CN 3- abducts, elevates, and laterally rotates eye
Levator palpebrae superioris- CN3- elevates superior eyelid

Question 3

All eye muscles are the oculomotor nerve except?

Answer 3

Torochlear (4) superior oblique (goes through a trochlear)

Abducent CN 6: lateral rectus

Question 4

What muscles are used to close eyelids?

To open eyelids?

Answer 4

Orbicularis oculi contracts and levator palpebrae relaxes

To open: levator palpebrae superioris contracts

Question 5

What are the glands that secrete oily substance into tears?

Answer 5

Tarsal glands

Question 6

What is the syndrome were you have a drooping superior eyelid cause by loss of sympathetic innervation to superior tarsus muscle.

Answer 6

Ptosis: in Horners syndrome

Question 7

Be able to label the diagram in slide 21

Answer 7

Ya

Question 8

Be able to label the bones making the orbit on slide 22

Answer 8

Ljdbc

Question 9

What are the parts that make u the lacrimal apparatus?

Picture on slide25

Answer 9

Consist of the:
Lacrimal gland: secretes lacrimal fluid (watery physiological saline containing lysozyme and O2)
Excretory ducts: lacrimal fluid from gland to conjunctival sac
Lacrimal canaliculi (small canals)
Lacrimal punctum (opening)
Lacrimal papilla
Lacrimal lake (where tears collect)
Lacrimal sac (diluted superior part of duct)
Nasolacrimal duct –> inferior nasal meatus

Question 10

What is the parasympathetic innervation of the lacrimal gland?

Answer 10

Secretomotor parasympathetic fibre from facial nerve (CN 7) via pterygopalatine ganglion
Sympathetic: inhibits tears
Parasympathetic: creates tears

Question 11

Development
Were do the retina, iris and optic nerve originate from?
What forms from the ectoderm?
Mesenchyme?

Answer 11

The brain. Reason why the optic nerve is coated in the 3 layers of the cranial meninges!
Surface ectoderm –> lens, cornea, conjunctiva, eyelashes, lacrimal glands.
Mesenchyme–> choroid, sclera, tarsal plates, orbicularis oculi

Question 12

Describe the optic tract

Answer 12

The optic nerves meet at the optic chiasm then to the optic tract and end at the lateral geniculate body (midbrain)

Question 13

Rods and cones. What do they specialise in?

Answer 13

Rods: dim light, peripheral vision receptors
Cones: bright light, high acuity colour receptors

Question 14

Normal retina
What is the optic disc
Fovea centralis

Answer 14

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 accurate vision, only comes

Question 15

What used to be in the hyaloid canal?

Answer 15

Because when we are an embryo less than 10 weeks old we have an artery that is supplying the lens and letting it grow. It regresses and it no longer gets supplied from blood vessels. Instead lens will get nutrients from the vitreous fluid

Question 16

What is the function of the vitreous body?

Answer 16

• holds the eye in shape

- vision, it is a high density substance which magnifies and refracts the light to focus it onto the fovea centralis

Question 17

Tunic of the eyeball

Label diagram on slide 35

Answer 17

Fibrous: sclera (white): tough, opaque, supplied by arteries cornea (clear): transparent, avascular, highly innervated by nerves from CN5-V1
Vascular: choroid, ciliary body, and iris
Nervous coat: retina (2 layers, neural layer and retinal pigmented epithelium) important because it changes the colour of our eyeball

Question 18

Corneal blink reflex:
Afferent limb (sensory) ie which nerve is sensory to brain
Efferent limb (motor from brain)

Answer 18

Afferent: opthamic branch from trigeminal
Efferent: facial

Question 19

Cataract

Answer 19

Clouding of lens
Scatters light entering the eye ie light can’t focus so will make vision blurry
- fixed by removing lens and replacing it

Question 20

Aqueous humour

Answer 20

Fills and shapes anterior and posterior chambers of eye

• provides nutrients to avascular lens and cornea, removes wastes
• secretion from ciliary processes
• ciliary processes –> posterior chamber –> through pupil –> anterior chamber
• circadian rhythm of flow: higher in morning than at night

Question 21

Glaucoma. What is this condition

Answer 21

Impaired aqueous humour outflow
Elevated intracellular pressure
Optic nerve damage

Question 22

Ciliary body and iris

Answer 22

Ciliary body connect choroid to iris
Ciliary body processes secrete aqueous humour
Autonomic innervation of muscles of iris.

Question 23

What is the disease when there is a hole in the iris?

Answer 23

Coloboma

Question 24

Pupillary reflexes

Answer 24

Slow sympathetic response ie dilation
Fast parasympathetic fibres by ciliary nerves ie constriction
Under autonomic control

Question 25

What happens when there is an absence of nerve stimulation to the eye?

Answer 25

The ciliary muscle relax, the k
Zonular fibres are under tension
Lens is stretched then to refract light for distant vision

Question 26

What happens when parasympathetic stimulation causes ciliary muscle to contract?

Answer 26

Zonular fibres relax.
In the absense of stretching, internal tension causes lens to become more spherical (thicker) to refract light for near vision

Question 27

What happens when the aqueous humour pressure decreases?

Answer 27

It may cause the retina to separate slide 50.

Vision impairment and blindness

Question 28

Macula degeneration

Answer 28

Chronic disease no cure,

Leading causes of blindness