Ocular Anatomy 14 Vasculature and Cavernous Sinus Flashcards
What is the first branch of the ICA after it emerges from the cavernous sinus
Ophthalmic artery
What is the path of the ophthalmic artery?
Passes from cavernous sinus inferolateral to the optic nerve in the optic canal within dural sheath
Above optic nerve in 85% of cases as enters the orbit
Gives off central retinal artery which passes below the nerve
What are the branches of the ophtahlmic artery?
Long and short posteiorr ciliary arteries
Anteiror and posteiror ethmoidal arteries (to ehtmoidal sinuses)
Supraorbital artery (to frontal sinus)
TEmirnal - supratrochlear and dorsal nasal arteries
Where does the Central retinal artery lie in relation ot the optic nerve? Path?
Lies inferolateral to optic nerve as it branhes from ophthalmic artery
Passes inferior to the optic nerve
Pierces dural sheath approximately 12mm behind the globe
Travels obliquely through the subarachnoid space and gives off a number of small meningeal branches that supply pial sheath of optic nerve
What is the blood supply to the sclera?
Long posterior, short posterior and anterior ciliary arteries
what is the path of the long posterior ciliary arteries?
Pierce scelra outside circle of Zinn and travel forard in the suprachoroidal space to the cilairy body where the contribute to the major arterial arcade
Recurrent branches supplying the choroid anterior to the equator anastamose with the short posterior ciliary arteries
What is the path of the short posterior ciliary arteries
Divide into 10-20 branches pierce the sclera around the optic nerve
Anastomotic circle of Zinn supplies optic nerve head with more anterior branches supplying the choroid as far as equator
What do the anterior ciliary arteries supply?
Two arteries accompany each rectus muscle except the LR which only has one
Supply the sclera and conjunctiva as well as major arterial circle of iris
What is the venous drainage of the globe?
Superior ophthalmic vein formed by supraorbital and facial veins
Receives contributions from superior vortex veins and central retinal vein
Inferior ophthalmic vein receives the inferior vortex veins and usually drains into the superior ophtahlmic vein
Communicates with pterygoid venous plexus
All drain into cavernous sinus
What drains into the cavernous sinus?
Superior ophthalmic vein
Inferior ophthalmic vein
Sphenoparietal sinus (accompanies MMA)
Inferior and superficial middle cerebral vein
Where are cavenous sinuses located?
Between inner meningeal and outer endosteal layers of dura mater
Situated on either side of the body of the sphenoid bone
What is the risk to the cavernous sinus from the pterygoid venous plexus
Spread of infection as orbital veins have no valves
Causing cavernous sinus thrombosis
How does the cavernous sinus communicate with the pterygoid venous plexus?
Emissary veins via the foramen ovale or foramen of Vesalius
How does the cavernous sinus drain?
Via superior and inferior petrosal sinus into the sigmoid sinus and internal jugular vein via jugular foramen
What are the boundaries of the cavernous sinus?
Superior orbital fissure anteirorly
Apex of petrous part of temporal bone posteriorly
Floor formed by dural covering of greater wing of sphenoid bon
