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Ocular Anatomy and Physiology > Week 11: Choroid and Ocular Blood Supply > Flashcards

Week 11: Choroid and Ocular Blood Supply Flashcards

1
Q

What is blood?

A
  • It is the fluid in our bodies that maintains life and our existence
  • Composed of plasma, platelets, leukocytes (WBCS) and erythrocytes (RBCs)
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2
Q

Describe the aorta

A
  • Beginning at the top of left ventricle & supplies oxygenated blood to circulatory system
  • R and L subclavian: arms
  • R and L common carotid: neck and brain
  • Divides into Internal and External carotid arteries on both sides of the body
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3
Q

What does carotid arteries brach into and what does it supply?

A

Divides into:

  • Internal carotid artery: supplies brain & eye
  • External carotid artery: supplies face & neck
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4
Q

What is the internal carotid artery process?

A

Enter the skull and then traverse the cavernous sinus

  1. Surrounded by plexus of sympathetic nerves from superior cervical ganglion
  2. CNII & CNIII accompany the internal carotid as it leaves the sinus
  3. Ophthalmic artery branches from internal carotid artery as it emerges from the cavernous sinus
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5
Q

Describe cavernous sinus

A
  • Drains blood from the brain

- Located within the middle cranial fossa, on either side of sella turcica of the sphenoid bone

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6
Q

What are the structures transversing the cavernous sinus?

A
  • Oculomotor nerve (CN III)
  • Trochlear nerve (CN IV)
  • Trigeminal nerve (CNV): ophthalmic (V1) and maxillary (V2) branches
  • Abducens nerve (CN VI)
  • Internal carotid artery and carotid plexus
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7
Q

Where does each cavernous sinus receive ocular venous drainage from?

A
  • Ophthalmic veins (superior & inferior)

- Central retinal vein

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8
Q

Describe the condition of cavernous sinus thrombosis

A
  • Rare
  • Common cause: infection from an extracranial location
  • Symptoms: headache, periorbital oedema, proptosis
  • Treatment: antibiotic therapy
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9
Q

Describe ophthalmic artery

A
  • Enters orbit within dural sheath of the optic nerve and passes through optic canal
  • Primary blood supply to the globe and adnexa
  • Branching pattern of the OA is very complicated and unique
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10
Q

What are the major branches of ophthalmic artery?

A
  1. Central retinal artery
  2. Lacrimal artery
  3. Short & Long Posterior ciliary arteries
  4. Anterior & Posterior ethmoidal artery
  5. Supraorbital artery
  6. Muscular arteries
  7. Medial palpebral arteries
  8. Supratrochlear artery
  9. Dorsonasal artery
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11
Q

Describe Central retinal Artery

A
  • First & smallest branch of ophthalmic artery
  • Enters the optic nerve 8-15 mm behind the globe and moves forward within the optic nerve
  • Sympathetic nerve plexus surrounds artery
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12
Q

Describe lacrimal artery and their main branches

A
  1. Long posterior ciliary arteries
  2. Muscular branch
  3. Zygomatic branches
  4. Lacrimal gland
  5. Lateral palpebral arteries
  • Largest branch ophthalmic artery
  • Runs forward to supply lacrimal gland with lacrimal nerve
  • Supplies branches to lateral rectus muscle
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13
Q

What is the blood supply to EOM of lacrimal artery?

A
  1. Lateral rectus

2. Superior rectus

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14
Q

List the Posterior Ciliary Arteries

A
  1. Short Posterior Ciliary Arteries
  2. Long Posterior Ciliary Arteries
  3. Cilioretinal (Nasociliary) Arteries
  4. Anterior Ciliary Arteries
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15
Q

Describe Short Posterior Ciliary Arteries

A

The major blood flow to the optic nerve head is from:

  1. Short posterior ciliary arteries
  2. Peripapillary choroidal arteries
  3. Circle of Zinn–Haller
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16
Q

Describe Long Posterior Ciliary Arteries

A
  • Run between the sclera and the choroid to the anterior globe
  • Enter & supply the ciliary body, branch superiorly, inferiorly and anastamose with Short Posterior Ciliary Artery
17
Q

Describe Cilioretinal (Nasociliary) Arteries

A
  • As they are separate to the central retinal artery, they also emerge from the disc separately
  • Supply the macula
18
Q

Describe Anterior Ciliary Arteries

A
  • Branches from vessels supplying rectus muscles
  • Prior, sends branches to conjunctiva and episclera
  • Enters the ciliary body & anastomose with branches of long posterior ciliary arteries forming Major Arterial Circle of Iris
19
Q

Describe the Ethmoidal Arteries branches and what they supply

A
  1. Anterior ethmoidal artery
    - Supplies anterior sphenoid sinus, frontal & nasal cavity and skin of nose
  2. Posterior ethmoidal artery
    - Supplies the ethmoid sinus and sphenoid sinus
20
Q

Describe the Supraorbital Artery

A
  • Arises from Ophthalmic artery running upward towards superior EOM
  • Supplies skin & muscles of forehead and scalp
21
Q

What is the blood supply to EOM of supraorbital artery?

A
  1. Superior rectus
  2. Superior oblique
  3. Levator muscle
22
Q

Describe Muscular Arteries and what does the lateral/superior and medial/inferior branch supply

A

Lateral/superior branch supplies:

  1. Lateral rectus
  2. Superior rectus
  3. Superior oblique
  4. Levator muscle

Medial/inferior branch supplies:

  1. Medial rectus
  2. Inferior rectus
  3. Inferior oblique
23
Q

List what is in palpebral Arteries

A
  1. Marginal Arcades
  2. Peripheral Arcades
  • Anastomose with lateral branches
24
Q

Describe Supratrochlear Artery

A
  • Supplies the skin and muscles of the forehead and scalp

- Anastomoses with supraorbital artery & external carotid

25
Q

Describe Dorsonasal Artery

A
  • Sends vessels to supply the lacrimal sac and nose

- Anastomoses with external carotid

26
Q

What is the blood supply to EOM of infraorbital artery?

A
  1. Inferior rectus

2. Inferior oblique

27
Q

Describe the ocular venous drainage

A
  • Veins have no valves
  • Two ophthalmic veins
  • Internal venous drainage via vortex veins which drain into ophthalmic veins
28
Q

Describe the Superior Ophthalmic Vein

A
  • Largest ophthalmic vein,
- Drains blood from:
•  Anterior and posterior ethmoidal veins
• Muscular vein
• Lacrimal vein
• Central retinal vein
• Superior vortex veins
29
Q

Describe the Inferior Ophthalmic Vein

A 
- Drains blood from:
• Inferior and lateral EOM’s
• Inferior conjunctiva
• Lacrimal sac
• Inferior vortex veins
30
Q

Describe the choroid

A
  • Extremely vascular
  • Thin, soft brown coat on inner surface of sclera
  • Posteriorly (0.2 mm) & anteriorly (0.1 mm)
31
Q

List the functions of the choroid

A
  • Nutrition for outer retina
  • Secretion of growth factors
  • Modulation of IOP
  • IOP drainage via uveoscleral pathway
  • Pigment cells absorb any excess light
32
Q

What are the Choroidal Layers?

A
  1. Choroidal Stroma (External)
  2. Choriocapillaris (Middle)
  3. Bruch’s membrane (Internal)
33
Q

Describe the choroidal stroma

A
  • Loose connective tissue
  • Medium & large blood vessels embedded
  • 4 to 5 large vortex veins exit the eye
34
Q

Describe Choriocapillaris

A
  • Network of capillaries

- Density of capillaries is greatest at the macula

35
Q

Describe the Bruch’s membrane

A
  • Innermost layer of the choroid
  • Molecular sieve regulating the exchange of nutrients & waste products
  • Does not contain blood vessels
36
Q

What are the five layers of Bruch’s membrane

A
  1. Basement membrane of choriocapillaris
  2. Outer collagen fibre layer
  3. Elastic fibre layer
  4. Inner collagen fibre layer
  5. Basement membrane of the retinal pigment epithelium
37
Q

Describe the choroidal blood supply

A
  • Arterial supply: ophthalmic artery branches from internal carotid artery
  • Posterior Ciliary arteries branch from ophthalmic artery to supply choroid
  • Venous drainage is via the vortex veins, which drain into the ophthalmic veins
38
Q

Describe the choroidal nerve supply

A
  • Innervated by long & short ciliary nerves (from CNV, V1)
  • Long ciliary nerves innervates: ciliary muscle & iris dilator
  • Parasympathetic fibres from ciliary ganglion innervate:
    • iris sphincter
    • ciliary muscle
    • choroidal vessels.

Ocular Anatomy and Physiology (10 decks)

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