Exam 1 - 004 Overview of Ocular Circulation

Question 1

Pathway of the Ophthalmic Artery

Answer 1

 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

Question 2

Branches of the Ophthalmic Artery

Answer 2

	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

Question 3

What is the direct origin of the medial and lateral palpebral arteries?

Answer 3

Lacrimal artery

Question 4

What is the pathway of the lacrimal artery?

Answer 4

 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

Question 5

Origin of SPCA

Answer 5

 Medial and lateral posterior ciliary arteries

Question 6

Origin of LPCA

Answer 6

 Posterior Ciliary Arteries

Question 7

Pathway of the central retinal artery

Answer 7

• 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

Question 8

Structures supplied by the central retinal artery

Answer 8

• 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

Question 9

Path of the short posterior ciliary arteries

Answer 9

 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

Question 10

Structures supplied by the SPCA

Answer 10

 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

Question 11

Pathway of the LPCA

Answer 11

 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

Question 12

Structures supplied by LPCA

Answer 12

 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)

Question 13

Pathway of the anterior ciliary arteries and their recurrent branches

Answer 13

 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)

Question 14

Structures supplied by the anterior ciliary arteries and their recurrent branches

Answer 14

 Sclera (major perforating branches)
 Choroid anterior to the equator of the eyeball (recurrent branches)
 Iris (MAC)
 Ciliary Body (MAC)

Question 15

What is the major arterial circle of the iris (MAC)?

Answer 15

o It is the anastomosis of the superior and inferior branches of the LPCA with the anterior ciliary arteries

Question 16

What makes up the MAC

Answer 16

o 2 LPCA
 Superior and inferior branches
o 7 anterior ciliary arteries

Question 17

What supplies the choroid?

Answer 17

	Anterior to the equator
•	2 LPCA
•	7 anterior ciliary arteries
	Posterior to the equator
•	15-20 short posterior ciliary arteries

Question 18

What supplies the central part of the optic nerve behind lamina cribrosa?

Answer 18

 Central Retinal Artery

Question 19

What supplies the lamina cribrosa of the optic nerve

Answer 19

 15-20 short posterior ciliary arteries

Question 20

What supplies the central retinal layers

Answer 20

 Central Retinal Artery

Question 21

What supplies the iris?

Answer 21

 2 LPCA

 7 anterior ciliary arteries

Question 22

What supplies the ciliary body?

Answer 22

 2 LPCA

 7 anterior ciliary arteries

Question 23

What supplies the sclera?

Answer 23

 15-20 short posterior ciliary arteries
 2 LPCA
 7 anterior ciliary arteries

Question 24

Central Retinal Vein

Answer 24

 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

Question 25

What does the central retinal vein receive blood from and drain into?

Answer 25

	Receives blood from
•	Capillaries supplying the inner layers of the retina
	Drains into
•	Cavernous sinus OR
•	Superior ophthalmic vein

Question 26

Superior Ophthalmic vein

Answer 26

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

Question 27

Inferior Ophthalmic Vein

Answer 27

 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

Question 28

What does the inferior ophthalmic vein receive blood from and drain into?

Answer 28

	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

Question 29

Vortex Veins

Answer 29

	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

Question 30

Infraorbital Veins

Answer 30

	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

Question 31

Vortex Vein Ampulla

Answer 31

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

Question 32

Supraorbital Artery Pathway

Answer 32

 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

Question 33

Structures supplied by the supraorbital artery

Answer 33

 Levator palpebrae superioris
 Superior rectus
 Superior oblique
 Skin and muscles of the forehead and scalp

Question 34

Ethmoidal arteries

Answer 34

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

Question 35

Supratrochlear Artery

Answer 35

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

Question 36

Medial Palpebral arteries

Answer 36

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

Question 37

Nasal Artery

Answer 37

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

Question 38

Infraorbital Artery

Answer 38

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