Exam 1 - 004 Overview of Ocular Circulation Flashcards
Pathway of the Ophthalmic Artery
Branches from the internal carotid artery
Enters the orbit through the optic canal
• Inferior and lateral to the optic nerve
• Lies within the muscle cone formed by the four rectus muscles that arise from the common tendinous ring
In the orbit it runs forward a short distance between the optic nerve and lateral rectus
Turns medial
Crosses above the optic nerve
Proceeds to the medial wall with the nasociliary nerve
Travels forward along the medial wall with the nasociliary nerve, giving off branches as it goes
Branches of the Ophthalmic Artery
Central Retinal A* Lacrimal A Muscular branches Posterior Ciliary arteries • Long posterior Ciliary A. (LPCA)* • Short Posterior Ciliary A (SPCA)* Supraorbital A Supratrochlear A Anterior Ethmoidal A Posterior Ethmoidal A Medial Palpebral A Dorsal Nasal A Meningeal A • Variable • Runs posteriorly through SOF to anastomose with the middle meningeal artery in the middle cranial fossa *supplies the eyeball, along with anterior ciliary arteries
What is the direct origin of the medial and lateral palpebral arteries?
Lacrimal artery
What is the pathway of the lacrimal artery?
Lacrimal A. Runs forward on the upper border of the lateral rectus (with the lacrimal nerve
• While in the orbit it supplies the lacrimal gland
Pierces the orbital septum
Terminates as the lateral palpebral arteries (2)
• Supplies that skin and conjunctiva of the lateral half of the upper and lower eyelids
Origin of SPCA
Medial and lateral posterior ciliary arteries
Origin of LPCA
Posterior Ciliary Arteries
Pathway of the central retinal artery
• Branches from the ophthalmic artery after it enters the orbit
• Runs under the optic nerve
• Eventually pierces the optic nerve about 10-12 mm posterior to the eyeball
o Passes through the center of the optic nerve
Structures supplied by the central retinal artery
- The central part of the optic nerve from its point of entry into the optic nerve to the posterior border of the lamina cribrosa
- INNER layers of the retina
Path of the short posterior ciliary arteries
Arise from the medial and lateral Posterior Ciliary Arteries (about 7-10 of them)
Pierce the back of the eyeball in a ring around the optic nerve
Run forward in the space between the sclera and the choroid
• The space is called suprachoroidal space
Structures supplied by the SPCA
Sclera near where they enter the eyeball
Some supply the posterior portion of the choroid up to the equator
Others anastomose in the sclera to supply the laminar part of the optic nerve
• As the circle of Zinn-Haller
Pathway of the LPCA
Branch from the Posterior Ciliary Arteries (one medial and one lateral)
Pierce the sclera at the back of the eyeball
Run forward in the suprachoroidal space to the ciliary body
• Divides into superior and inferior branches at the ciliary body
• Superior and inferior branches anastomose with each other and the anterior ciliary arteries
o forms the major arterial circle of the iris (a discontinuous arterial ring which is in the CILIARY BODY)
LPCA gives off 3-5 recurrent branches at the ora serrata
• Pass directly back to the choroid anterior of the equator
Structures supplied by LPCA
Sclera where they enter the eyeball
Iris at the major arterial circle of the iris
Ciliary body the major arterial circle of the iris
Choroid anterior to the equator of the eyeball (supplied by the recurrent branches)
Pathway of the anterior ciliary arteries and their recurrent branches
Originate from the muscular arteries that supply the four rectus muscles
• 2 for SR, MR and IR
• 1 for LR
After supplying the muscles, the 7 muscular arteries continue anteriorly as the anterior ciliary arteries
• ACA pass forward
• Bifurcates just beyond the rectus muscle insertions
o Some branches continue forward beneath the bulbar conjunctiva (episcleral arteries)
o Some branches pierce the sclera (major perforating branches)
Gives off 8-12 recurrent branches that pass backwards to supply the choroid anterior to the equator of the eyeball
After giving off the branches, MPB joins the LPCA in the ciliary body to form the major arterial circle of the iris (MAC)
Structures supplied by the anterior ciliary arteries and their recurrent branches
Sclera (major perforating branches)
Choroid anterior to the equator of the eyeball (recurrent branches)
Iris (MAC)
Ciliary Body (MAC)
What is the major arterial circle of the iris (MAC)?
o It is the anastomosis of the superior and inferior branches of the LPCA with the anterior ciliary arteries
What makes up the MAC
o 2 LPCA
Superior and inferior branches
o 7 anterior ciliary arteries
What supplies the choroid?
Anterior to the equator • 2 LPCA • 7 anterior ciliary arteries Posterior to the equator • 15-20 short posterior ciliary arteries
What supplies the central part of the optic nerve behind lamina cribrosa?
Central Retinal Artery
What supplies the lamina cribrosa of the optic nerve
15-20 short posterior ciliary arteries
What supplies the central retinal layers
Central Retinal Artery
What supplies the iris?
2 LPCA
7 anterior ciliary arteries
What supplies the ciliary body?
2 LPCA
7 anterior ciliary arteries
What supplies the sclera?
15-20 short posterior ciliary arteries
2 LPCA
7 anterior ciliary arteries
Central Retinal Vein
Formed from tributaries corresponding roughly to the branches of the central retinal artery
Leaves the eye by passing through the optic nerve with the central retinal artery through the SOF
What does the central retinal vein receive blood from and drain into?
Receives blood from • Capillaries supplying the inner layers of the retina Drains into • Cavernous sinus OR • Superior ophthalmic vein
Superior Ophthalmic vein
larger than the inferior ophthalmic vein Receives blood from • Don’t need to know but: o Muscular branches (from SO, SR, MR and levator palpebrae superioris) o Lacrimal vein o Ethmoidal veins • Supraorbital vein • Supratrochlear vein • Angular vein • Central retinal vein (in some cases • Superior vortex veins (which receive blood from the choroid) Drains into • Cavernous sinus Passes through the SOF above the common tendinous ring
Inferior Ophthalmic Vein
Arises from a venous plexus on the anterior floor of the orbital cavity
• SAYS WE DON’T NEED TO KNOW THIS
Passes posteriorly on the inferior rectus muscle
Pathway
• Passes through SOF below the common tendinous ring to drain into the cavernous sinus
• Passes through the IOF to drain into the pterygoid venus plexus
What does the inferior ophthalmic vein receive blood from and drain into?
Receives blood from • Angular vein • Inferior vortex vein • Don’t need to know these: o Muscular branches (from IR, IO and LR) o Inferior conjunctiva and lacrimal sac Drains into • Cavernous sinus • Pterygoid venous plexus
Vortex Veins
Usually four, one for each quadrant of the eye • Can vary from 3 to 6 Receives blood from (drains) • Areas supplied by the LPCA and SPCA including the choroid and portions of the ciliary body and iris Drains into • Superior side o Superior ophthalmic vein • Inferior side o Inferior ophthalmic vein
Infraorbital Veins
Receives blood from • Facial vein Drains into • Pterygoid venous plexus Passes posteriorly through the infraorbital foramen, infraorbital canal and infraorbital groove. Then exits the orbit through the IOF
Vortex Vein Ampulla
o Located at the equator of the eyeball
o The dilated beginning of the vortex vein
Site where the choroidal veins drain
Together, the choroidal veins and the ampula look like an octopus – the choroidal veins are tentacles and the ampula the body
o Exits the eyeball about 6 mm posterior to the equator of the eyeball
o Readily visible during a DFE with a BIO
Supraorbital Artery Pathway
In the orbit it passes forward above the levator palpebrae superioris
• Travels with the supraorbital nerve
Exits the orbit through the supraorbital foramen
Anastomosis with superficial temporal and supratrochlear arteries on the scalp
Structures supplied by the supraorbital artery
Levator palpebrae superioris
Superior rectus
Superior oblique
Skin and muscles of the forehead and scalp
Ethmoidal arteries
o Anterior Ethmoidal A Supplies • Anterior, middle and posterior ethmoidal air cells • Frontal sinus • Nasal cavity • Skin of the nose o Posterior Ethmoidal A Supplies • Posterior ethmoidal air cells • Sphenoid sinus
Supratrochlear Artery
o One of the terminal branches of the ophthalmic artery
o Pathway
Leaves the orbit on the medial side by piercing the orbital septum above the puller for the superior oblique
• Travels with the supratrochlear nerve
Anastomosis with superficial temporal and supraorbital arteries in the scalp
o Supplies
Skin of the forehead and scalp
Muscles of the forehead
Medial Palpebral arteries
o Two arteries
o Pathway
Arise from the anterior portion of the ophthalmic artery just below the pulley for the superior oblique
Pierce the orbital septum
Anastomosis with lateral palpebral arteries
o Supplies
Medial half of the upper and lower eyelids and conjunctiva
Nasal Artery
o One of the terminal branches of the ophthalmic artery
o Pathway
Leaves the orbit on the medial side by piercing the orbital septum below the pulley for the superior oblique
Sends branches to the lacrimal sac
Runs along the side of the nose to anastomose with the angular artery
Infraorbital Artery
o Pathway
Branches from the maxillary artery
Enters the orbit through the IOF
Passes forward through the infraorbital groove, infraorbital canal and infraorbital foramen
Exits the orbit by passing through the infraorbital foramen
Gives off the anterior superior alveolar artery to supply the maxillary sinus and upper teeth
o Supplies
Inferior rectus muscle
Inferior oblique muscle
Lacrimal sac
