Blood Supply

what does external carotid artery do

provides blood to superficial areas of head and neck

important external carotid artery branches

facial artery, maxillary artery, superficial temporal artery

where does the facial artery branch and where does it go

branches at the mandible

goes across the cheek to the medial canthus of the eye

what is the terminal branch of the facial artery

angular artery

function of angular artery

supplies medial canthus

communicates with the dorsal nasal artery (from the ophthalmic artery)

where does the maxillary artery start

in front of the ear in the parotid gland

what branch of the maxillary artery enters the orbit

infraorbital artery

where does the infraorbital branch of the maxillary artery enter and leave the orbit

enters the orbit through the inferior orbital fissure

leaves the orbit through the infraorbital foramen

what does the infraorbital branch of the maxillary artery supply

when it enters the orbit: IO, IR

when it leaves the orbit: lower lid, lacrimal sac

where does the infraorbital branch of the maxillary artery go when it leaves the orbit

joins the angular artery and the dorsal nasal artery

where does the superficial temporal artery start

parotid gland

what does the superficial temporal artery supply

skin, muscles, and soft tissue of the face and orbit

what artery does the superficial temporal artery communicate with

ophthalmic artery (supraorbital branch)

what ocular arteries are damaged in giant cell arteritis (GCA)

short posterior ciliary arteries (in the circle of Zinn) are damaged

causes damage and suffocation of the ON leading to irreversible vision loss

superficial temporal artery becomes inflamed in GCA

what does the internal carotid artery do

provides blood to structures in the cranium

what part of the internal carotid artery helps the external carotid artery supply areas of the superficial face and orbit

terminal branches of ophthalmic nerve

what happens if the supraorbital artery (branch of ophthalmic artery) is obstructed and cannot provide blood to the orbit

the supraorbital artery (of the ophthalmic artery) anastomoses with the superficial temporal artery

if the SOA is obstructed, the STA will temporarily provide a low level of circulation to the orbit

where does the ICA enter the skull and where does it go

enters through the petrous part of the temporal bone

travels through the cavernous sinus

what travels alongside the ICA in the cavernous sinus

CN VI

where are CN II and CN III located in relation to the ICA in the cavernous sinus

CN II is medial to the ICA as it exits the sinus

CN III is lateral to the ICA as it exits the sinus

what is the first branch of the ICA towards the orbit

ophthalmic artery

what would most likely be affected if there was an aneurysm of the ICA within the cavernous sinus

CN VI

where does the ophthalmic artery enter the orbit

optic nerve sheath

where does the ophthalmic artery travel after leaving the ON sheath

near medial wall of orbit between the LR and SO

what does the ophthalmic artery travel with after leaving the ON sheath

nasociliary nerve

branches of the ophthalmic artery

central retinal artery, lacrimal artery, muscular artery, short posterior ciliary artery, long posterior ciliary artery, supraorbital artery, ethmoid artery

what is the first branch of the ophthalmic artery

central retinal artery

path of CRA

travels in ON, enters optic disc nasally, divides into multiple superior and inferior branches

what does the CRA supply

optic nerve and surrounding pia mater that it is traveling through

inner 2/3 of retina

lacrimal artery path

travels along lateral wall of orbit with lacrimal nerve

branches and terminates into lateral palpebral artery

what does lacrimal artery supply

lateral rectus & lacrimal gland

what does lacrimal artery terminate into

lateral palpebral artery

what does the lateral palpebral artery supply

lateral inferior and superior lids

what forms the palpebral arcades

lateral (lacrimal artery branch) and medial (dorsal nasal artery branch) palpebral arteries anastomose to form palpebral arcades of the eyelids

what does the muscular artery supply

EOMs

name of 2 branches of the muscular artery

superior lateral and inferior medial

what does the superior lateral muscular artery supply

LR, SR, SO

what does the inferior medial muscular artery supply

MR, IR, IO

what are the anterior ciliary arteries made up of

branches of the muscular artery that supply the four recti muscles

pathway of short posterior ciliary arteries

1-2 large branches enter the eye on either side of the ON and branch 10-20 times within the choroidal stroma

in the choroidal stroma, SPCA branches form the arterial network that supplies the ON head known as the circle of zinn

what do the SPCAs supply

posterior choroid and macula

what is the circle of zinn

branches of SPCAs that form a network in the choroidal stroma to provide blood to the optic disc

pathway of long posterior ciliary arteries

2 arteries enter the eye on either side of the ON and travel between the choroid and sclera, joining the SPCAs to supply blood to the choroid

they continue traveling forward to the ciliary body to join the anterior ciliary arteries and form the major arterial circle of the iris

what do the LPCAs supply

anterior choroid, ciliary body, iris

blood supply of the choroid

SPCAs supply posterior choroid (post seg)

LPCAs supply anterior choroid (ant seg)

what makes up the major arterial circle of the iris

anterior ciliary arteries from the muscular artery that supplies the recti

LPCAs

what is the major arterial circle of the iris

fenestrated capillaries in the ciliary body that leak out plasma, allowing aqueous humor to form

made up of anterior CAs and LPCAs

path of the supraorbital artery

goes into the orbit and exits the orbit through the supraorbital notch

what does the supraorbital artery supply

in the orbit: SR, SO, levator

once it exits the orbit, it supplies the superficial scalp and forehead alongside the superficial temporal artery of the ECA

what does the ethmoid artery supply

sphenoid, frontal, and ethmoid sinuses

what are the 2 terminal branches of the ophthalmic artery

supratrochlear artery & dorsal nasal artery

what does the supratrochlear artery supply

skin of the forehead and scalp, muscles of the forehead

pathways of dorsal nasal artery

supplies lacrimal sac and travels down side of nose to join angular artery (of facial artery of ECA) and later infraorbital artery (of maxillary artery of ECA)

what does the dorsal nasal artery supply

lacrimal sac

what does the dorsal nasal artery branch into

medial palpebral arteries that supply medial upper and lower lids and form palpebral arcades

ocular ischemic syndrome is the occlusion of the ________________

internal carotid or ophthalmic artery

how are orbital veins similar to veins in the head and neck (unlike the rest of the body)

do not contain valves

venous drainage does not correspond to arterial supply

central retinal vein pathway

exits the eye through the ON and enters the cavernous sinus (alone or with superior ophthalmic vein)

where does central retinal vein drain from

inner 6 layers of the retina supplied by the CRA

anterior ciliary vein pathway

follow path of anterior ciliary arteries across the recti and drain into superior and inferior ophthalmic veins

what do anterior ciliary veins drain

blood from anterior parts of the eye: ciliary body, conjunctiva, Schlemm’s canal

what do vortex veins drain

blood from choroid, at least 1 vein in each quadrant

largest vein in the orbit

superior ophthalmic vein

veins that drain into the superior ophthalmic vein

central retinal vein, superior vortex veins, muscular veins from the SR, SO, & MR (anterior ciliary veins), lacrimal vein

origin of the superior root of the superior ophthalmic vein

branches of the supraorbital and supratrochlear

where in the orbit does the superior root of the superior ophthalmic vein originate

superomedial orbital rim

origin of the inferior root of the superior ophthalmic vein

branches of the angular vein (of the facial vein)

what 2 roots form the superior ophthalmic vein and where

superior and inferior root of superior ophthalmic vein

join together behind the trochlea and medial to the superior rectus

where does the inferior ophthalmic vein originate

network of veins along the anterior medial orbital floor between the globe and IR

veins that drain into the inferior ophthalmic vein

muscular veins (drain the IR, IO, LR), inferior vortex veins, small veins (drain inferior conjunctiva, lower lid, lacrimal sac)

where do the 2 branches formed by the inferior ophthalmic vein exit the orbit

inferior branch: inferior orbital fissure

superior branch: superior orbital fissure

where do the inferior and superior branches of the IOV drain

inferior: pterygoid plexus to communicate with facial veins

superior: cavernous sinus, joining superior ophthalmic vein

where does the supraorbital vein originate

forehead

the supraorbital vein sends a branch through the ____________ to help form the ____________

supraorbital notch; superior ophthalmic vein

where does the frontal vein originate

venous plexus on the forehead

what 2 veins form the angular vein

supraorbital vein and frontal vein

where does the angular vein originate

side of nose at the medial angle of the orbit

what 2 anterior vein branches help form the SOV

supraorbital branch of supraorbital vein and nasofrontal branch of angular veins

what vein does the angular vein form into and where

anterior facial vein at the inferior orbit margin

where does the anterior facial vein get blood from

superior and inferior palpebral veins, pterygoid venous plexus branch

what forms the common facial vein

anterior facial vein travels from the side of the nose to the masseter and joins the posterior facial vein forming the common facial vein

where does the common facial vein drain

internal jugular vein

what drains into the infraorbital vein

small superficial veins that drain the inferior orbit

where does the infraorbital vein enter the orbit and travel

enters the infraorbital foramen

travels along orbital floor in infraorbital groove

where does the infraorbital vein empty

pterygoid venous plexus

where is the pterygoid plexus located

infratemporal fossa

what does pterygoid plexus communicate with

anterior facial veins and cavernous sinus

what does the pterygoid venous plexus form

maxillary vein

what forms the posterior facial vein

superficial temporal vein and maxillary vein

what forms the superficial temporal vein

frontal and parietal branches of venous plexus

what vein originates from lateral palpebral venous branches

orbital vein

where does the orbital vein drain

middle temporal vein

where is the posterior facial vein formed

parotid gland

what does the anterior branch of the posterior facial vein do

joins anterior facial vein to form common facial vein and drains into internal jugular vein

what does the posterior branch of the posterior facial vein do

joins the posterior auricular vein to form the external jugular vein

where does the occipital vein originate

posterior vertex of the skull

where does occipital vein drain

internal jugular vein or posterior auricular vein to go to external jugular vein

what is the external jugular vein

formed by retromandibular and posterior auricular veins, drains blood from superficial face

what is the internal jugular vein

continuation of sigmoid sinus, drains blood from internal facial veins

what are dural sinuses

venous channels in the dura mater of the brain that drain blood from the head back to the heart