Orbital Blood Supply

internal carotid artery

runs upward through the neck and enters the skull via carotid canal, leaves canal and immediately enters cavernous sinus, exits sinus through roof

ophthalmic artery

first major branch from internal carotid artery; branches from internal carotid as it exits cavernous sinus medial to anterior clinoid process of sphenoid bone

central retinal, lacrimal, SPCA, LPCA, ethmoid, supraorbital, muscular, medial palpebral, supratrochlear, dorsonasal

list the branches of the ophthalmic artery

lacrimal, supraorbital, posterior ethmoidal, anterior ethmoidal, medial palpebral, supratrochlear, dorsalnasal

list the branches of the ophthalmic artery in the orbital group

central retinal, muscular, long posterior, short posterior, anterior ciliary

list the branches of the ophthalmic artery in the ocular group

central retinal artery

• pierces dural sheath of optic nerve 12mm behind the globe

• gives off small meningeal branches to supply the pial sheath of the optic nerve

• passes through lamina cribosa and enters optic disc on nasal side

• branches into superior and inferior, then nasal and temporal

lacrimal artery

• one of the largest ophthalmic branches

• lateral

• runs along upper border of lateral rectus muscle and supplies branches to the muscle

• supplies blood to lacrimal gland

zygomaticotemporal artery

• branch of lacrimal artery

• exits orbit via zygomaticotemporal foramina

zygomaticofacial artery

• branch of lacrimal artery

• exits orbit via zygomaticofacial artery

lateral palpebral arteries

formed by terminal branches of the lacrimal artery that pass forward through the gland, pierce the orbital septum, and enter lateral side of upper and lower eyelids

long posterior ciliary arteries

• paired arteries that pierce the sclera outside the circle of Zinn

• travel forward in supra-choroidal space to ciliary body

• branches anastomose with each other and with anterior ciliary arteries to form MACI

  • gives recurrent branches that supply the choroid anterior to equator and anastomose with SPCAs

short posterior ciliary arteries

• 10-20 branches pierce sclera around optic nerve

• circle of Zinn, supplies optic nerve head

• supplies choroid to the equator

• supply sclera and conjunctiva and the iris

posterior ethmoid artery

• branch of ophthalmic artery near medial wall

• enters ethmoid bone

• passes through posterior ethmoid canal to supply posterior ethmoid and sphenoid sinus

• sends branches into nasal cavity to supply upper part of nasal conchae

anterior ethmoid artery

• branch of ophthalmic artery near medial wall

• enters ethmoid bone

• larger branch

• passes through anterior ethmoid canal and supplies anterior & medial ethmoid sinuses, sphenoid sinus, frontal sinus, nasal cavity, and skin of nose

supraorbital artery

• branch of ophthalmic artery medial to optic nerve

• passes through supraorbital notch then divides into 2 branches to supply the skin and muscles of the forehead and scalp

• sends branches to superior rectus, superior oblique and levator muscles in the orbit

muscular arteries

• branch from ophthalmic artery as 2 branches, lateral and medial

lateral branch of muscular artery

supplies lateral rectus, superior rectus, superior oblique, and levator muscles

medial branch of muscular artery

supplies medial rectus, inferior rectus, and inferior oblique muscles

medial rectus

which EOM is the only EOM to receive blood supply from just the muscular artery?

anterior ciliary artery

• branch from vessels supplying rectus muscles

• exit muscles near muscle insertions, run forward along tendons, then loop inward to pierce sclera outer to limbus

• send branches to conjunctiva

• enter ciliary body and anastomose with LPCA and form MACI

• 7 (2 from each rectus muscle except LR)

medial palpebral arteries

• branch directly from ophthalmic artery or from dorsonasal artery near trochlea of superior oblique

• pierce orbital septum on either side of medial palpebral ligament and enter superior and inferior eyelids

medial palpebral & lacrimal arteries

what 2 arteries anastomose to form the palpebral arcades?

palpebral arcades

• formed by medial palpebral & lacrimal arteries

• 2 in each lid

• provide blood supply for eyelid structures

supratrochlear artery

• one of the terminal branches of the ophthalmic artery

• pierces orbital septum at superior, medial corner of the orbit

• passes w/ supratrochlear nerve upward to supply skin and muscles of forehead and skin of scalp

dorsonasal artery

• one of the terminal branches of the ophthalmic artery

• leaves orbit by piercing the orbital septum below trochlea above medial palpebral ligament

• sends vessels to supply the lacrimal sac then runs alongside the nose to anastomose w/ angular artery from external carotid

• medial

external carotid artery

branch of common carotid, passes upwards through tissue of the neck

facial artery

branch of external carotid near angle of mandible, runs along posterior edge of lower jaw, then curves upward over outside of the jaw and across the cheek to the angle of the mouth

angular artery

branch from facial artery sent to medial canthus, supplies the lacrimal sac

superficial temporal artery

• terminal branch of external carotid

• branches into anterior temporal, zygomatic, and transverse facial arteries

anterior temporal artery

• supplies the skin and muscles of the forehead and anastomoses with the supraorbital and supratrochlear arteries

• superficial temporal artery branch

zygomatic artery

• superficial temporal artery branch

• extends above the zygomatic arch and supplies orbicularis muscle

transverse facial artery

• superficial temporal artery branch

• supplies skin of cheek and anastomoses with infraorbital artery

maxillary artery

• branch of external carotid artery

• runs along pterygopalatine fossa and enters orbit through inferior orbital fissure as infraorbital artery

infraorbital artery

• runs forward along infraorbital groove in maxillary bone, passes through infraorbital canal, and exits through infraorbital foramen

• supplies lower eyelid and lacrimal sac

medial muscular artery

what supplies blood to the medial rectus muscle?

lateral muscular & lacrimal artery

what supplies blood to the lateral rectus muscle?

lateral muscular, lacrimal, supraorbital artery

what supplies blood to the superior rectus muscle?

medial muscular, infraorbital artery

what supplies blood to the inferior rectus muscle?

lateral muscular, supraorbital artery

what supplies blood to the superior oblique muscle?

medial muscular, infraorbital artery

what supplies blood to the inferior oblique muscle?

no

do veins of the orbit have valves?

2

how many ophthalmic veins are there?

superior ophthalmic vein

• formed by joining of angular and supraorbital veins

• larger

• runs with ophthalmic artery and passes posteriorly, receives blood from veins that drain superior orbital structures

• passes below superior rectus, crosses ON, exits superior orbital fissure to empty to cavernous sinus

central retinal vein

• venous branches in retinal tissue join to form this

• leaves ON ~10-12mm behind lamina cribosa along retinal artery

• emerges from meningeal sheath of ON and joins superior ophthalmic vein or exits orbit and drains into cavernous sinus

vortex veins

• 4, one in each quadrant

• drains choroid

inferior ophthalmic vein

• starts as plexus near anterior floor of orbit

• drains blood from lower and lateral muscles, inferior conjunctiva, lacrimal sac, and inferior vortex veins

• can branch into one that empties into superior ophthalmic vein/cavernous sinus and one that empties into pterygoid venous plexus

anterior ciliary veins

receive branches from conjunctival capillary network then pierce the sclera and join muscular veins

infraorbital vein

• formed by several veins that drain face

• receives branches from some structures in inferior orbit and may communicate with inferior ophthalmic vein

• drains into pterygoid venous plexus

fluorescein angiography

identifies leakages and occlusions in retina

internal carotid artery stenosis

clinical condition where ICA is not as open as it should be, identifiable with fluorescein angiography because dye is slow to exit

retinal venous branch occlusion

clinical condition where there is a compression of the vein at the crossing of the central retinal artery and vein; restriction of flow results in retinal edema and hemorrhage in the area surrounding the occlusion

anterior ischemic optic neuropathy

clinical condition resulting from nonperfusion or hypoperfusion of the ciliary blood supply to the ONH

conjunctivitis

red eye involving the infection of superficial blood vessels, giving conjunctiva a bright-red color that often increases towards fornix; vessels move with conjunctival movement and can be blanched with a topical vasoconstrictor

uveitis

red eye where deeper scleral and episcleral vessels are injected, gives the circumlimbal area a purplish or rose-pink color; vessels do not move with conjunctiva and are not blanched with a topical vasoconstrictor