Ocular Anatomy Flashcards
terminology
- right eye
- left eye
- both eyes
- OD Oculus dexter
- Right eye
- OS Oculus sinister
- Left eye
- OU Oculi uterque
- Both eyes
Orbital Anatomy
- species comparison
- *Extraocular Muscles**
- *• Innervation**
- Oculomotor (CN III)
- Dorsal (superior) rectus, ventral (inferior) rectus, medial rectus, and ventral (inferior) oblique muscles
- Trochlear (CN IV)
- Dorsal (superior) oblique muscle
- Abducens (CNVI)
- Retractor bulbi muscle, lateral rectus
Rectus muscles
Dorsal (superior), ventral (inferior), medial, lateral
Rotate globe in the direction of their name
Innervated by CN III except lateral rectus CN VI
Oblique muscles
- Dorsal (superior) oblique muscle (CN IV) intorsion of globe
- Ventral (inferior) oblique muscle (CN III) extorsion of globe
Eyelid Anatomy
- Components
- Functions
- Components:
- Skin
- Cilia
- Subcutaneous CT
- Muscles
- Meibomian glands
- Conjunctiva
- Functions:
- Corneal protection
- Production, distribution, and drainage of tear film
Eyelid Muscles
Orbital Glands
- Orbital lacrimal gland
- ~60-70% of aqueous tear fluid
- Superior-temporal orbit
- Gland of the 3rd eyelid gland
- Base of 3rd eyelid
- ~ 30-40% of aqueous tear fluid
Nasolacrimal System
Conjunctiva
- Mucus membrane
- Palpebral conjunctiva
- Lines inner surface of eyelids
- Bulbar conjunctiva
- Covers surface of globe
- Nictitans membrane
- Conjunctival fornices
Layers of the Eye
- Fibrous tunic
- Cornea
- Sclera
- Vascular tunic
- Anterior uvea
- Iris
- Ciliary body
- Posterior uvea
- Choriod
- Anterior uvea
- Neural tunic
- Retina
Cornea
- Epithelium
- Stroma
- Descemet’s membrane
- Endothelium
Cornea
- innervation
- clarity
- thickness
Corneal Epithelium
- Descemet’s membrane
- Endothelium
Sclera
- Limbus
- Corneoscleral junction
- Variably pigmented
- Lamina cribosa
- Optic nerve passes through sclera
- Scleral thickness
- Varies considerably
- Thinnest near the equator
- dog 0.12mm
Uveal Tract
- Anterior uvea
- Iris
- Ciliary body
- Posterior uvea
- Choroid
- Tapetum
- Choroid
Iris
- muscles
- innervation
Ciliary Body
Aqueous Humor Outflow
• Conventional outflow pathway
→ Ciliary body epithelium
→ Posterior chamber
→ Pupil
→ Anterior chamber
→ Iridocorneal angle
→ Vortex veins
→ Systemic circulation
Aqueous Humor Outflow
• Unconventional outflow pathway
- Uveoscleropathway
- Iris stroma
- Ciliary body stroma
- Supraciliary-suprachoroidal space
- Sclera
- Systemic circulation
- Species variation
• 3% cat
• 15% dog
• ~50% horse
Aqueous Humor Outflow
- conventional vs unconventional (diagram)
Posterior Uvea
- Choroid
- Comprised primarily of blood vessels
- Choriocapillaris
- Main source of nutrition for outer layers of retina
- Tapetum
- Large vessel layer
Tapetum Lucidum
- Reflective layer in the inner choroid
- Dorsal fundus
- Allows second stimulation of photoreceptors
- Lack tapetum
- Humans, red kangaroo, squirrels, llamas, alpacas, and pigs
- Internal limiting membrane
- Nerve fiber layer
- Ganglion cell layer
- Inner plexiform layer
- Inner nuclear layer
- Outer plexiform layer
- Outer nuclear layer
Rod and cone nuclei - Outer limiting membrane
- Rod and cone layer
- Retinal pigment epithelium
Retina
- Rods and cones
- Rods dim light
- Shapes and motion
- Cones daylight
- Color vision
- Visual acuity
- Area centralis-area of high cone density in domestic animals
- Fovea-primates, some avian and reptile species; cone-rich area
- Rods dim light
- Potential space between RPE and photoreceptors
- Retinal detachments
- Retina is firmly attached
- Optic nerve head
- Ora ciliaris retinae
Holangiotic Vascular Pattern
Merangiotic Pattern
Paurangiotic
Anangiotic
Lens
- Lens capsule
- Canine anterior lens capsule 50-70 um
- Canine posterior lens capsule 2-4 um
- Anterior epithelium
- Lens fibers
- Equator
- Nucleus
- Cortex
Vitreous Humor
- Occupies up to 2/3 volume of globe
- Transparent, jellylike material
- ~99% water, collagen and hyaluronic acid
- Functions
- Transmit light
- Maintain the normal retinal position
Optic Nerve
nerve pathway
- Retinal ganglion cells axons leave nerve fiber layer and form optic nerve
- Optic nerve
- Optic chiasm
- Decussation
- Humans 50%
- Cats 67%
- Dogs 75%
- Horse 85%
- Birds 100%
- Decussation