The document summarizes the orbital blood supply. The ophthalmic artery is the first main branch of the internal carotid artery and gives rise to numerous branches that supply the orbit and eye. These branches include the central retinal artery, lacrimal artery, muscular branches, and ciliary arteries. The central retinal artery supplies the retina. The lacrimal artery supplies the lacrimal gland and eyelids. Venous drainage is mainly through the superior and inferior ophthalmic veins which drain into the cavernous sinus.

1. Orbital Blood Supply
Othman Al-Abbadi, M.D
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2. Ophthalmic artery
 The first main branch of the internal carotid
artery.
 Course:
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Relation to the optic
nerve
Relation to the
meninges
Pre-optic canal Inferolateral Subarachnoid
Optic canal Inferolateral Dural-Arachnoid sheath
Orbital cavity Lateral Extra-dural
Superior 85%
Inferior 15%

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6. Branches
1. Central artery of the retina
2. Lacrimal artery
3. Muscular branches
4. Ciliary arteries
5. Supraorbital artery
6. Posterior ethmoidal artery
7. Anterior ethmoidal artery
8. Meningeal artery
9. Medial palpebral arteries
10. Supratrochlear arteries
11. Dorsal nasal artery
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7. Central retinal artery
 First branch from the ophthalmic artery.
 End arteries.
 Course:
◦ Runs beneath optic nerve, then at about
1.25cm behind eyeball it pierces the dural &
arachnoid sheaths of optic n, enters eyeball
through lamina cribrosa
 Divides into equal superior & inferior
branches, then another division (nasal &
temporal).
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8.  Branches:
◦ Small meningeal branches supply the pial
sheath
◦ Central collateral branches which pass with
the CRA to the lamina cribrosa & a branch
goes posteiorly to supply the macular nerve
fibers
 Circle of Zinn occurs between the pial
vessels & the small vessels in the sclera
around the nerve head.
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11. Lacrimal artery
 Runs on upper border of the LR, passes
through lacrimal gland & sends terminal
branches to the eyelids & conjunctiva.
 Branches:
◦ Lateral palpebral to the U & L eyelids &
anastomose with the medial palpebral
◦ Zygomatic which pass through the
zygomaticofacial & zygomaticotemporal
foraminae
◦ Muscular branch to the LR
◦ Recurrent meningeal anastomoses with the
middle meningeal artery.
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14. Muscular branches
 Most of these branches accompany
the branches of the oculomotor nerve.
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15. Ciliary arteries
1. Long posterior ciliary artery
◦ 2 in no.
◦ Pierce the sclera & run in the epichoroidal space
to the ciliary body where they divide into upper &
lower branches & encircle iris
◦ Anastomose with the anterior ciliary arteries to
form the major arterial circle of iris..
◦ recurrent branches supply the choroid posteriorly to
the equator & anastomose with the short posterior
ciliary arteries
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16. 2. Short posterior ciliary arteries:
◦ 7 in no.
◦ divide into 10-20 branches
◦ run around the optic nerve before piercing the sclera to
supply the choroid as far as the equator where they
anastomose with recurrent branches of the LPCA, ACA &
the major arterial circle of the iris
 A number of small branches form an anastomotic
ring(ring of Zinn) around optic disc with the pial
arteries
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17.  Cilioretinal artery
◦ ~15-20% of the population
◦ Enters the retina at the lateral border of the
optic nerve & supplies the retina between the
disc & the macula
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19. 3. Anterior ciliary arteries
◦ 7 in no.
◦ originate from the muscular branches
◦ Join the LPCA to form the major arterial
circle of iris.
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22. Supraorbital artery
 Runs at the medial border of the SR & LPS then
with the supraorbital nerve between the LPS &
orbital roof,
 leaves orbit through the supraorbital foramen &
ascends to the scalp deep to the frontalis
 Anastomose with supratrochlear & superficial
temporal arteries
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23. Posterior ethmoidal artery
 Passes between the upper border of the MR &
SO muscles to enter the posterior ethmoidal
canal
 Supplies posterior ethmoidal air sinuses, dura of
anterior cranial fossa & upper part of nasal
mucosa.
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24. Anterior ethmoidal artery
 Larger
 Enters anterior ethmoidal canal then
anterior cranial fossa & passes into the
nose through cribriform plate down in a
groove in the nasal bone to enter face
between the nasal bone & upper cartilage
 supplies ant. & middle ethmoidal air cells,
frontal air sinus, meninges, ant. nasal
mucosa & skin of nose.
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25. Meningeal artery
 Runs posteriorly through the superior
orbital fissure to supply meninges of
middle cranial fossa.
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26. Medial palbebral atery
 Arise below the pulley for the SO
 Descend behind the lacrimal sac
 pierce the orbital septum above & below the
medial palpebral ligament
 form peripheral & marginal arterial arches
 Run between the orbicularis oculi & the tarsal
plate
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27. Supratrochlear artery
 Terminal branch
 Pierces the orbital septum above pulley for the
SO
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29. Dorsal nasal artery
 Terminal branch
 Pierces the orbital septum
 Passes above medial palpebral ligament &
descends to nose, gives branches to lacrimal sac
& anastomoses with the facial artery
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30. Arterial Supply of Eyeball
 Outer 1/3rd (up to the outer nuclear layer)
is avascular & supplied by the choroidal
vessels
 Inner 2/3rd by the CRA
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32. Veins of the Orbit
 Tortuous & freely anastomose with one
another
 No valves
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33. Superior ophthalmic vein
 Larger
 formed by union of supraorbital & facial
veins
 communicates with CRV, then recieves
IOV & 2 vorticose veins from the upper
part of the eyeball
 Leaves the orbit through superior orbital
fissure to join the cavernous sinus.
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37. Inferior Ophthalmic vein
 Arises from venous plexus in orbital floor,
 Communicates with facial v & pterygoid venous
plexus,
 Receives muscular branches & 2 inferior
vorticose v,
 Drains into the cavernous sinus or the pterygoid
venous plexus.
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38. Central retinal vein
 Leaves the eyeball by piercing lamina cribrosa
with the CRA
 Drains into cavernous sinus or SOV.
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