Blood supply to the eye and adnexa

Question 1

GIve 6 reasons there is a blood supply to the eye

Answer 1

-provides oxygen, nutrients and water
-removes carbon dioxide and metabolic wastes
-hormones
-to mediate the immune system response
-to maintain a constant pH and temperature
-source of pressure

Question 2

What is the common carotid and what does it consist of?

Answer 2

the main artery that supplies blood to the head and neck

theres a left and a right carotid artery and each divides into the internal carotid and the external carotid

Question 3

what is the infraorbital artery?

Answer 3

a branch of the external carotid that provides blood supply to the eye

Question 4

what is the circle of Willis? What arteries does it contain?

Answer 4

the cerebral arterial circle that provides alternative passages for blood flow in case another gets blocked. It contains
-the internal carotid arery
-the middle cerebral artery
-the basilar artery
-vetebral artery

Question 5

what is the ophthalmic artery?

Answer 5

a branch of the internal carotid that provides blood supply to the adnexa

Question 6

what are the main branches of the ophthalmic artery?

Answer 6

-central retinal artery
-lacrimal artery
-posterior ciliary arteries ( short and long)
-muscular arteries that branch to form:
-anterior ciliary arteries
-supraorbital artery
-medial palpebral arteries

Question 7

for the central retinal artery,
what structures does it go through and what is it accompanied by?

Answer 7

-goes through the optic nerve behind the eye and the central optic disk
-accompanied by the central retinal vein

Question 8

how does the central retinal artery supply blood to the optic nerve?

Answer 8

via collateral branches

Question 9

what forms the blood-retina barrier?

Answer 9

endothelial cells of retinal capillaries and retinal pigment epithelial cells capillaries via tight junctions by zonula occludens

Question 10

what is autoregulation in the retina?

Answer 10

the maintenance of constant blood flow despite the changes in intraocular pressure and systemic blood pressure controlled by metabolism

Question 11

how does the Bruch’s membrane change with age?

Answer 11

1. it thickens
2. it causes decreased permeability

Question 12

how is dry AMD diagnosed?

Answer 12

staining of the large drusen in the retina as a result of the bruch’s membrane allowing for extracellular debris

Question 13

what supplies the choroid with blood?

Answer 13

posterior ciliary arteries

Question 14

what supplies the iris and ciliary body with blood?

Answer 14

anterior ciliary arteries as they anastomose with the branches of the long posterior ciliary arteries

Question 15

what do the short posterior ciliary arteries supply?

Answer 15

posterior choroid, optic nerve, pia matter of the optic nerve and in some cases the inner retina

Question 16

what do the long posterior ciliary arteries supply?

Answer 16

ciliary body, anterior choroid and major arterial circle of the iris

Question 17

what are the two muscular arteries and what do they supply?

Answer 17

-lateral superior artery supplies, lateral rectus, superior rectus, superior oblique and levator muscle
-medial inferior artery supplies, medial rectus, inferior rectus and inferior oblique

Question 18

what does the lacrimal artery pass through and what does it supply?

Answer 18

passes through the lacrimal gland and supplies the lacrimal gland, conjunctiva and the lids , it anastomoses the medial palpebral artery

Question 19

which arteries provide blood supply for the photoreceptors?

Answer 19

the short posterior ciliary arteries and long posterior ciliary arteries

Question 20

which arteries provide blood supply for the majority of retinal ganglion cells in our eyes?

Answer 20

the central retinal arteries

Question 21

what does the central retinal artery branch off?

Answer 21

the ophthalmic artery

Question 22

Give two reasons for the need of a dual blood supply to the retina

Answer 22

-the blood supply in the inner retina is only enough for the retinal ganglion cells, intermediary neurones and muller cells. As the outer retina has high oxygen requirements, the nutrients need to have a separate blood supply
-as photoreceptors are metabolically active in the dark producing ATP hence use up alot of oxygen supplied from the choroid and so causing the conc of o2 to steeply decrease from the choroid towards the inner segment layer where it is close to zero meaning no o2 can diffuse into the inner retina

Question 23

which arteries provide branches that supply the optic nerve?

Answer 23

-the central retinal artery
-the short posterior ciliary arteries