ORBIT & OCULAR ADNEXAE - Orbital Blood Vessels Flashcards
Where does the ophthalmic artery arise from?
Arises from medial aspect of ICA medial to the anterior clinoid process at foramen lacerum junction (ICA passes through here)
Fill in the blanks.
What is the first branch of the ophthalmic artery?
central retinal artery.
What is the route of the central retinal artery?
Travels below optic nerve
then pierces upwards around the dural sheath and arachnoid of optic nerve 12mm behind globe and gives off some small pial branches.
then travels within the optic nerve through to the lamina cribrosa into the retina at nasal side of optic disc.
Then divides into superotemporal, superonasal, inferotemporal and inferonasal branches to supply INNER SIX layers of retina.
What supplies the fovea?
Ciliary/choroidal circulation.
What is the route of the ophthalmic artery?
INFERIOR to optic nerve —> LATERAL to optic nerve —> LATERAL COMPARTMENT –> above optic nerve to MEDIAL COMPARTMENT –> superiorly –> towards medial orbit.
travels inferior to optic nerve, then takes a turn and goes lateral to optic nerve.
Gives two branches at lateral compartment here,
1. the lacrimal artery (runs above lateral rectus and supplies lacrimal gland).
2. recurrent meningeal artery - travels in lateral part of SOF and anastamoses with middle meningeal artery (branch of ECA)
after going laterally, ophthalmic artery travels above optic nerve and reaches medial compartment of the orbit passing below superior rectus. Gives branch here the posterior ciliary arteries either side of the optic nerve (lateral and medial PCA).
As ophthalmic artery travels above optic nerve it gives one branch (supraorbital arteries) and two more braches: medial and lateral mscular artery.
It now encounters the medial wall of orbit and gives rise to two arteries - anterior and posterior ethmoidal arteries (which passes through their foramen respectively)
It then travels anteriorly in medial compartment and gives rise to its terminal branches at the trochlea of the superior oblique - dorsal nasal and supratrochlear artery.
Name a branch of the lacrimal artery.
the lateral palpebral artery - supplies the eyelids.
What is the route of the medial and lateral posterior ciliary arteries?
Divide into short and long posterior ciliary arteries.
Some short arteries form plexus around optic disc form Zinn of Haller.
Long posterior Passes in suprachoroidal space all along until the ciliary body where anastomoses with anterior ciliary artery to form the major arterial circle of iris.
What is the circle of Zinn and Haller?
plexus formed between the posteiror ciliary arteries above the optic nerve head –>
the PCA is main source of blood supply to optic nerve head and adjacent retrolaminar part of optic nerve
What is the cause of anterior ischaemic optic neuropathy?
Results from non-perfusion/hypoperfusion of the ciliary blood supply to the optic nerve head –> usually results in sectoral disc oedema and altidunal field defect as either the superior or inferior portion is affected (the cilioretinal blood supply is SEGMENTAL)
What do the short posterior ciliary arteries supply?
Short posterior ciliary arteries supply the outer 4 layers of the retina (RPE, photoreceptors, ELM and outer nuclear layer)
Supply intraocular part of optic nerve
What do the long posterior ciliary arteries supply?
choroid (anterior to the equator), ciliary body and iris (outer 4 layers of retina).
Where does the short posterior ciliary arteries terminate?
Short posterior ciliary arteries pierce sclera and supply choroid in segmental manner terminate at the posterior region.
Where does the long posterior ciliary artery terminate?
Long posterior pierce the sclera oblique and enter suprachoroidal space reaching the ciliary body where anastomoses with anterior ciliary artery to form the major arterial circle of iris.
What is the difference between the short and the long posterior ciliary arteries? (2)
1. Difference in number
2. Difference in branches
- number - LPCA (2) , SPCA (2)
- branches - LPCA (0) , SPCA (10-20)
What is the route of the supraorbital artery?
accompanies supraorbital nerve and travels just below orbital roof and above superior rectus and LPS and leaves through the supraorbital notch.
What is the difference between the medial and lateral muscular arteries?
Medial muscular : supplied medical aspect - medial rectus, inferior rectus and inferior oblique
Lateral muscular artery: supplies LPS, and lateral rectus and superior rectus, superior oblique.
What are the terminal branches of the muscular arteries (medial and lateral)?
The anterior ciliary artery
How many anterior ciliary arteries are there?
7 anterior ciliary arteries - 2 for each recti, one for the lateral rectus
What is the route of the anterior ciliary artery?
Pierces sclera near the limbus to enter the ciliary body and form the major arterial circle with the long posterior ciliary artery 4mm from the lmbus.
What does the anterior ciliary artery supply?
Supply sclera, conjunctiva, limbus and extraocular muscles.
What forms the major and minor arterial circles?
Major: anastamoses of long posterior ciliary artery and anterior ciliary artery around the iris.
Minor: branches from major run radially into iris as iris vessels and anastamose at pupillary margin forming minor arterial circle.
What arteries form the superior and inferior marginal arcades? How many arcades are in the upper eyelid vs lower eyelid?
anastamoses of lateral and medial palpebral arteries. 2 in upper eyelid, one in lower eyelid.
How far are the vortex veins away from the limbus?
They exit 14-25mm away from the limbus between rectus muscles.
Where do the vortex veins drain into?
Superior vortex veins –> superior ophthalmic vein
inferior vortex veins –> inferior ophthalmic vein
join with central retinal vein to the cavernous sinus.
What vessel supplies the intracranial part of the optic nerve? (4)
- recurrent branch of anterior superior hypophyseal artery (supplies inferior optic nerve)
- anterior cerebral artery (supplies superior optic nerve)
- ophthalmic artery
- anterior communicating artery
What is the course of the internal carotid artery?
picture
Which hole does the internal carotid artery go through?
Foramen lacerum
What are the branches of the ophthalmic artery?
picture
What branches does the ophthalmic artery give in the lateral compartment of the orbit? (2)
Gives a lacrimal branch –> lacrimal artery
Lacrimal artery gives branch lateral palpebral artery which supplies lateral side of eyelids
Recurrent meningeal artery –> travels in lateral SOF and anastamoses with middle meningeal artery (branch of external carotid artery)
What structures accompany the ophthalmic artery as it travels above the optic nerve in the medial compartment of the orbit? (2)
- Superior ophthalmic vein
- Nasociliary nerve
What branches does the ophthalmic artery give off in the medial compartment of the orbit?
Posterior ciliary artery –> divides into lateral and medial posterior ciliary arteries.
the long posterior ciliary arteries travel in the suprachoroidal space and reach ciliary body and form the major anastamosis
What do the short posterior ciliary arteries do?
Pierce sclera and supply choroid in segmental manner
Some branches form anastamotic ring around optic disc –> circle of Zinn-Haller
What is the anterior portion of the optic radiation supplied by?
anterior choroidal artery
What does the anterior ethmoidal artery supply?
What does the posterior ethmoidal artery supply?
Supply the ethmoid sinus, nasal cavity and skin of nose.
What does the inferior ophthalmic vein receive drainage from? Where does it send its drainage to?
Facial and angular veins
Sends drainage to cavernous sinus and pterygoid plexus
What is the route of the superior ophthalmic vein?
See picture
