Ocular: Orbital Vascular And Circulation Flashcards
What artery does the ophthalmic artery branch from?
Internal carotid artery
How does internal carotid artery enter the skull?
Carotid canal
How is the ophthalmic artery positioned relative to the optic nerve when it enters the orbit?
-lateral to the optic nerve in optic canal the courses overtop of nerve
-between MR and SO
**in 15% of people it goes under
3 regions that branch off the ophthalmic artery:
-ocular
-orbital
-extra orbital
What arteries are in the ocular region of the ophthalmic artery?
-central retinal artery
-ciliary arteries
What branches does the central retinal artery give off?
-small pial branches
What branches do the ciliary arteries give off?
Short and long posterior ciliary arteries
Long posterior ciliary arteries give off…
Medial and lateral branches
Short posterior ciliary arteries give off…
-10-20 branches
-may give rise to cilioretinal artery
What arteries are in the orbital region of the ophthalmic artery?
-muscular arteries
-lacrimal artery
Muscular arteries give off…
-7 anterior ciliary arteries (two to each rectus muscle except LR has one)
Which rectus muscle only has one anterior ciliary artery?
Lateral rectus
Lacrimal artery branches into:
-superior and inferior lateral palpebral arteries
-zygomatic artery and branches
What branches does the extra orbital region of the ophthalmic artery give off?
-supraorbital artery
-post. Ethmoidal artery
-ant. Ethmoidal artery
-recurrent meningeal artery
-medial palpebral artery
-supratrochlear artery
-dorsonasal artery
What are the terminal branches of the ophthalmic artery?
-supratrochlear
-dorsonasal
What is the first branch of the ophthalmic artery?
Central retinal artery (first and the smallest)
Course of central retinal artery and branches inside and outside the eye:
-branches inferior to optic nerve
-pierces dural sheath of optic nerve post. to sclera
-crosses subarachnoid space to enter substance of the nerve
-courses w/ central retinal vein
-crosses laminated cribrosa and enters the back of the eye
-small pial branches that supply pia
What is the position of the central; retinal artery relative to the central retinal vein in the optic disc?
-emerges on nasal side of optic disc just nasal to the central retinal vein
Lamina cribrosa is…
Very thin sclera
How many muscular arteries are there?
4
How many anterior ciliary arteries are there?
7
What do anterior ciliary arteries do?
They supply the rectus muscles (2 branches for each except LR has only 1)
Pathway of anterior ciliary arteries
-pierce sclera and join LPCA to form major arterial circle of iris
Arterial circle of iris is located in the…
Ciliary body
Anterior ciliary arteries can also stay on the surface to give rise to…
Conjunctival arteries
What are the branches of the external carotid artery that supply orbital and peri-orbital structures?
-facial artery
-infraorbital artery
-superficial temporal artery
Different paths of venous drainage:
-central retinal vein
-vortex veins
-anterior ciliary veins
-infraorbital veins
Where does superior ophthalmic vein drain?
Cavernous sinus
Where does inferior ophthalmic vein drain?
-pterygoid venous plexus
-superior ophthalmic vein
-cavernous sinus
Where is the superior ophthalmic vein located?
Outside the common tendinous ring, but in the SOF
Where is inferior ophthalmic vein located?
Outside the common tendinous ring but inside the IOF
What is a carotid-cavernous-sinus fistula?
Abnormal connection between carotid artery and cavernous sinus that leads to eye bulging, congestion, pulsing eyeball, headache, and droopy lid
Main causes for carotid-cavernous-sinus fistula
Trauma, aneurysm, and others
What is the main artery that supplies the eye?
Ophthalmic artery
Two vascular systems that supply the eye:
-retinal
-uveal: iris, ciliary body, choroid
What two parts of the uveal vascular system are located anterior?
Iris and ciliary body
What part of the uveal vascular is located posterior?
Choroid
Where is the Blood-aqueous-barrier (BAB) located in the iris?
In the non-pigmented layer of the ciliary epithelium in the posterior iridal epithelium
What prevents the blood from getting into the aqueous chamber?
Presence of tight junctions between endothelial cells
Why is the choroidal vascular so important for photoreceptors?
It is th only source of blood supply to the photoreceptors!
If blood supply to the photoreceptors was cut off…
The function would be compromised ad the cells may die
Are the capillaries of the choriocapillaries fenestrated or non-fenestrated?
Fenestrated
Why is the central retinal artery so important for the retina?
It provides small branches to optic nerve that supplies the inner layers of the retina
Where is the inner blood-retina layer located?
-In the retinal vessels
-made up of endothelial cells that line the blood vessels in retina
Why are pericytes important?
The give strength to the capillary cell wall
Where are pericytes located?
In tight junctions between endothelial cells apart of the blood-retina barrier
What happens to pericytes in diabetic retinopathy?
Diabetic retinopathy causes hyperglycemia which causes loss of pericytes leading to intro retinal hemorrhage and exudates
Location of outer blood-retina-barrier
Tight junctions between RPE cells
Location of inner blood-retinal-barrier
-Tight junctions between endothelial cells of retinal vascular
-include pericytes and glial cells
