Ocular Anatomy

All of the following muscles DEPRESS the eyebrow EXCEPT:

A) Procerus

B) Corrugator

C) Frontalis

D) Orbicularis oculi

What are the two glands found in the tarsal plate?

- Meibomian glands

- Gland of Wolfring

Where is the main lacrimal gland located?

fossa of frontal bone

Where are the accessory lacrimal glands located?

in the conjunctival stroma

Where are goblet cells located?

conjunctival epithelium

Horner's Syndrome

- Ptosis (from Muller's muscle, small, 2-3mm)

- Anhidrosis

- Miosis

--> Lack of sympathetic nervous system innervation

What muscle flares the nostrils?

--> Procerus

**Procerus = anything to do with nose

Major symptom of a nasolacrimal duct obstruction?

Unilateral epiphora

#1 cause of a nasolacrimal duct obstruction in a CHILD?

Valve of Hasner issue

#1 cause of a nasolacrimal duct obstruction in an ADULT?

Involutional stenosis (Age-related stenosis)

- Nasolacrimal duct narrows with age

- Next cause could be maxillary sinus infection (not as common)

Where does the lateral lymphatics drain?

preauricular lymph nodes

Where does the medial lymphatics drain?

submandibular lymph nodes

Major cause of Dacryocystitis? (infection of lacriminal sac)

Nasolacrimal duct obstruction

Major cause of Dacryoadenitis? (infection of lacriminal gland)

Staphylococcus

Systemic disease that is the #1 cause of Dacryoadenitis?

Sarcoid (causes inflammation)

What cranial nerve carries parasympathetic innervation to the lacrimal gland for lacrimination?

CN VII (vidian nerve)

What muscle compensates for a ptosis?

Frontalis

What sinus surrounds the nasolacrimal duct?

Maxillary sinus

The muscle of Muller is derived from...

Levator

What bones make up the lateral wall of the orbit?

Greater wing of sphenoid bone + Zygomatic bone

"great Z"

What bones make up the roof of the orbit?

Lesser wing of sphenoid bone + Frontal bone

"front less"

How many bones of the skull articulate to form the orbit?

7 bones

- Frontal

- Lacrimal

- Ethmoid

- Zygomatic

- Maxillary

- Palatine

- Sphenoid

3 things off the Lesser wing of sphenoid bone?

1) Levator (muscle of Muller)

2) Superior Oblique (EOM)

3) Optic nerve

Telecanthus

Abnormally increased distance between the medial canthi of the eyelids

Poliosis

Whitening of eyelashes

Madarosis

Loss of eyelashes

Trichiasis

Turning inward of eyelashes

- often secondary to ectropion

Phthiriasis palpebrarum

Infection of eyelashes caused by Phthirus pubis

What is the thinnest skin layer in the body?

The skin layer of eyelid

- Contains: fine hairs, sweat glands, sebaceous glands, NO fats

Subcutaneous areolar layer

Thin layer of loose connective tissue that lies between the outer skin the underlying orbicularis

- Upper lid subcutaneous areolar layer: contains levator

Submuscular Areolar Layer

Thin layer of loose connective tissue that lies between the orbicularis and orbital septum

- Upper lid submuscular areolar layer: contains levator and palpebral potion of main lacrimal gland

Orbicularis layer

Contains the palpebral portion of the orbicularis oculi, one of the muscles of facial expression innerved by CN VII

Orbital septum

Dense irregular connective tissue that serves as a barrier to the orbit in the upper and lower eyelids

- Orbital septum prevents fat from falling down onto the lid margins and keeps infections localized to the anterior portion of the eyelid away from the orbit

- Does NOT protect the lacrimal sac from infection

Periorbita = loosely covers the orbital bones. Projects anteriorly to become orbital septum and posteriorly to fuse with the dura of the optic nerve

Orbital septum continuous with periorbita and periosteum of the skull. Attaches medially to the posterior lacrimal crest.

Superior orbital septum serves as insertion site for the levator

What EOM inserts the closest to the limbus?

Medial rectus (clockwise)

What EOM inserts the furthest from the limbus?

Superior rectus

What VF defect does a pituitary gland tumor cause?

Bilateral hemianopsia

What are the 3 holes of the greater wing of the sphenoid bone?

1) foramen ovale (V3)

2) foramen spinosum (middle meningeal artery)

3) foramen rotundum (V2)

What nerve passes through the foramen rotundum?

V2 (maxillary division)

What nerve passes through the foramen ovale?

V3 (mandibular division)

What nerve passes through the foramen spinosum?

Middle meningeal artery

Posterior muscular system

Consists of the superior levator palpebrae muscle and the superior (i.e. Muller's muscle) and inferior tarsal muscles

superior palpebral levator muscle

- Originates from the lesser wing of the sphenoid at the orbital apex

- Main retractor of the upper eyelid

- Innervated by CN III

- Whitnall's ligament = superior transverse ligament on the zygomatic bone, serves as a fulcrum that changes the course of the muscle from anterior-posterior to superior-inferior

Eyelid furrows

Superior palpebral furrow = formed by the insertion of the levator aponeurosis into the skin of the upper lid

Inferior palpebral furrow = formed by the indirect attachment of the inferior rectus muscle into the skin of the lower eyelid

--> Eyelid furrows separate the tarsal and orbital potions of the eyelid

Tarsal plate

Dense irregular connective tissue that provide rigidity to the eyelids. Composed of horizontal and vertical collagen fibrils that surround the meibomian glands

Palpebral conjunctiva

Inner lining of the eyelids that contains 2 layers:

1) Epithelial layer

- Stratified outer protective layer that extends into the fornices and onto the bulbar conjunctiva

- Contains goblet cells that produce the mucin layer of the tear film

2) Stroma

- Loose vascularized CT composed of a superficial lymphoid layer and a deep fibrous layer

- Superficial lymphoid layer = very immunologically active layer, contains IgA, macrophages, mast calls, PNMs, eosinophils

- Deep fibrous layer = connects the conjunctiva to the underlying internal structures, contains the accessory lacrimal glands, nerves, BVs of the eyelids

Where are goblet cells?

- Caruncle

- Inferior nasal fornices

- Temporal bulbar conjunctiva

**none in the limbus

Iris sphincter vs. Iris dilator

Iris sphincter:

- Located in pupillary zone in iris stroma

- M3 receptors

Iris dilator:

- pupillary + ciliary zone

- alpha-1 receptors

- Located in anterior epithelium

Which layer of the eyelid contains goblet cells?

Palpebral conjunctiva (immunologically active, also has IgA antibodies)

What is another name for the ethmoid bone in the medial wall of the orbit?

Lacrimal papyracea

Which orbital wall does not utilize the sphenoid bone?

Floor

Obliques are main depressors/elevators...

51-55 deg ADducted (towards nose)

Rectii are main depressors/elevators...

23 deg ABducted (towards ears)

EOM attachments

- Obliques always attach BEHIND equator

- Rectii always attach IN FRONT of equator

What EOM has a different anatomical and physiological origin?

superior oblique

- Anatomical origin: lesser wing of sphenoid bone, CTR

- Physiological origin: trochlea

Which EOM would not be affected with a tumor located on the Annulus of Zinn?

Inferior oblique

What are the 2 types of sinuses within the cranium?

- Paranasal sinus (filled with air)

- Cavernous sinus (filled with venous blood)

3 branches of the Aortic arch?

"ABCS"

1) Brachiocephalic artery (right side)

- Breaks into ICA

2) Common carotid artery (left side)

3) Subclavian artery (left side)

Brachiocephalic artery

- Breaks into the 2 Vertebral arteries and the Internal carotid artery (ICA)

- ICA breaks into 4 branches

What are the branches of the Internal carotid artery (ICA)?

"OPAM" - 4 branches

1) Ophthalmic artery (7 branches, "CL MS LSE")

2) Posterior communicating artery (PCA)

3) Anterior cerebral artery

4) Middle cerebral artery

Ophthalmic artery

Branch off the ICA that goes directly to the eye

"CL MS LSE" - 7 branches

1) Central retinal artery (CRA)

2) Lacrimal artery

3) Muscular artery

4) Short posterior ciliary arteries (SPCAs)

5) Long posterior ciliary arteries (LPCAs)

6) Supraorbital artery

7) Ethmoidal artery

Circle of Willis

Junction between ICA and PCA

Includes:

- All branches of ICA ("OPAM")

- Pontine arteries

- Vertebral artery and branches

What arteries form the Circle of Willis?

- Posterior cerebral arteries

- Posterior and anterior communicating arteries

- Anterior cerebral arteries

- Basilar artery forms the BASE of the circle of willis

What arteries supply the choroid?

SPCAs and LPCAs

SPCAs = posterior choroid

LPCAs = anterior choroid

What supplies the inner retina (ILM to OPL)?

Central retinal artery

SPCAs vs. LPCAs

SPCAs:

- Supplies posterior choroid

- Supplies the optic disc (Circle of Zinn)

LPCAs:

- Supplies anterior choroid

- Supplies MACI (major)

Layers of the Retina

1) ILM

2) NFL

3) GCL

4) IPL

5) INL

6) OPL

7) ONL

8) ELM

9) PhR layer

10) RPE

Inner Retina

ILM to OPL

Outer Retina

OPL to RPE

SPCAs supplies...

- Posterior choroid

- Circle of Zinn (optic disc)

LPCAs supplies...

- Anterior choroid

- MACI

MACI

MACI = major arterial circle of iris

- Fenestrated

- Has non-pigmented ciliary epithelium (NPCE) and Beta-2 receptors

- Beta-2 receptor allows Na+ and Bicarbonate to pass in

Made up by:

- Anterior ciliary arteries (ACA)

- Long posterior ciliary arteries (LPCA)

Circle of Zinn

Supplies the optic disc

#1 way to produce aqueous humor?

Active transport

Cavernous sinus

Blood supply:

- SOV = superior ophthalmic vein

- IOV = superior ophthalmic vein

- Cavernous sinus drains into the sigmoid sinus

- Sigmoid sinus becomes the internal jugular vein

- Superficial cortical veins

Eye --> vortex veins --> --SOV and IOV--> Cav. sinus --> Sigmoid sinus --becomes--> Internal jugular vein --> Heart

Signs of trauma to the cavernous sinus?

- Pulsatile proptosis

- Chemosis of conjunctiva

Ex: carotid cavernous fistula (CCF)

What cranial nerves pass through the cavernous sinus?

CN 3, 4, 6, V1, V2 (only CN 7 and V3 do not)

+ ICA

What nerves go through the common tendinous ring?

"NOA"

Nasociliary nerve (V1)

Oculomotor nerve (CN III)

Abducens nerve (CN VI)

Foramens and openings in the orbits

What CN innervates what EOM?

SO_4LR_63

What EOMs are innervated by the superior division of CN III?

- Superior rectus

- Superior oblique

What EOMs are innervated by the inferior division of CN III?

- Inferior rectus

- Inferior oblique

- Medial oblqiue

Pathway of CN III

→ Brainstem

→ cavernous sinus

→ superior orbital fissure

→ Over/Under/Through common tendinous ring

Superior orbital fissure (SOF)

hole between the greater and lesser wing of the sphenoid bone

What foramen is located inside the common tendinous ring (CTR)?

optic foramen

- part of lesser wing of sphenoid

- where optic nerve comes through

Where do the oblique muscles attach?

BEHIND equator

Where do the rectii muscles attach?

in FRONT of the equator

What nerves travel through the superior orbital fissure?

CN 3, 4, 6, V1

(not V2)

What bones make up the floor of the orbit?

"My Pal gets his Z's on the floor"

Maxillary (majority)

Palatine

Zygomatic

What nerve runs below the eye along the floor of the obit that provides sensory innervation below eye?

V2 (inferior rectus)

Tolosa-Hunt syndrome

Inflammation of the SOF and/or cavernous sinus that often affects CN III, IV, V, VI

Signs: painful external ophthalmoplegia, diplopia

What is the main refracting element of the eye?

air/tear film interface

(contributes 44D to the refractive power of cornea)

What is the only miotic layer in the corneal epithelium?

basal layer

Fuchs' Dystrophy

- Corneal endothelium problem, endothelium makes too much Descemet and Descemet's membrane is very thick

Hemidesmosomes

- Connects basal cells of corneal epithelium to basal lamina of basement membrane

- Connects reticular lamina of basement membrane to Bowman's layer

**Hemi always connects something to basement membrane!

What 3 risk factors increase the risk of RCEs?

1) Poor hemidesmosomes attachments

2) Epithelial basement membrane dystrophy

3) Age-related thickening of the BM

What is the water content of the corneal stroma?

78% (detergescence)

What type of collagen is found in the corneal stroma?

Type 1 collagen

What type of collagen is found in Bowman's layer of the cornea?

Type 1 collagen

What type of collagen is found in the Decesmet's membrane of cornea?

Type 4 collagen

What part of the body has type 1 collagen?

"Bones, Bowmans, sclera, stroma"