Ocular Anatomy and Physiology Flashcards (Video Lecture Notes)

A vocabulary-style set of flashcards covering key terms and definitions from the lecture notes on ocular anatomy, physiology, tear system, and visual pathways.

Olfactory nerve (CN I)

Sensory nerve responsible for the sense of smell; the first cranial nerve.

Optic nerve (CN II)

Sensory nerve that transmits visual information from retina to the brain; part of the afferent visual pathway.

Oculomotor nerve (CN III)

Mixed nerve: motor to most extraocular muscles and levator palpebrae; parasympathetic fibers to the pupil and lens via the ciliary ganglion.

Trochlear nerve (CN IV)

Motor nerve that innervates the superior oblique muscle of the eye.

Trigeminal nerve (CN V)

Mixed nerve; three divisions (V1 ophthalmic, V2 maxillary, V3 mandibular) supplying sensation to the face and motor fibers to muscles of mastication.

Abducens nerve (CN VI)

Motor nerve that innervates the lateral rectus muscle, enabling abduction of the eye.

Facial nerve (CN VII)

Mixed nerve that innervates facial muscles and provides parasympathetic and sensory fibers to lacrimal and salivary glands.

Vestibulocochlear nerve (CN VIII)

Sensory nerve for hearing and balance.

Glossopharyngeal nerve (CN IX)

Mixed nerve supplying part of the tongue and pharynx with motor and sensory fibers.

Vagus nerve (CN X)

Mixed nerve supplying parasympathetic fibers to thoracic and abdominal organs and motor fibers to certain pharyngeal muscles.

Accessory nerve (CN XI)

Motor nerve supplying the sternocleidomastoid and trapezius muscles.

Hypoglossal nerve (CN XII)

Motor nerve that controls tongue movements.

LR6SO4R3

Mnemonic for extraocular muscle (EOM) innervation: Lateral Rectus (CN VI), Superior Oblique (CN IV), Rest (CN III) – all others by CN III.

Lateral Rectus (LR)

EOM responsible for abduction of the eye; innervated by CN VI.

Medial Rectus (MR)

EOM responsible for adduction of the eye; innervated by CN III.

Superior Rectus (SR)

EOM that elevates the eye and intorts; innervated by CN III.

Inferior Rectus (IR)

EOM that depresses the eye and extorts; innervated by CN III.

Superior Oblique (SO)

EOM that intorts, depresses (in abduction), and abducts; innervated by CN IV.

Inferior Oblique (IO)

EOM that extorts and elevates, especially when the eye is adducted; innervated by CN III.

Levator Palpebrae Superioris

Muscle that elevates the upper eyelid; innervated by the superior division of CN III.

Müller’s muscle (superior tarsal muscle)

Sympathetic smooth muscle that assists in lifting the upper eyelid.

Sphincter Pupillae

Parasympathetic circular muscle that constricts the pupil (miosis) via CN III.

Dilator Pupillae

Sympathetic radial muscle that dilates the pupil (mydriasis).

Ciliary Muscle

Muscle that smooths the lens via accommodation; innervated by parasympathetic fibers from CN III.

Ciliary Ganglion

Parasympathetic ganglion supplying the ciliary muscle and sphincter pupillae via short ciliary nerves.

Pupillary Light Reflex

Afferent limb: retina→CN II; Efferent limb: CN III to sphincter pupillae; constriction of pupil in response to light.

Direct Pupillary Reflex

Constriction of the pupil in the illuminated eye.

Consensual Pupillary Reflex

Constriction of the pupil in the opposite (fellow) eye when light is shone in one eye.

Near Pupillary Response

Convergence, accommodation, and pupil constriction in response to near objects.

Iris color genetics

Color determined by melanin in melanocytes; brown is dominant to blue; albinism involves lack of pigment.

Iris (structure)

Colored diaphragmatic curtain of the eye containing sphincter and dilator muscles; controls pupil size.

Ciliary body

Structure that makes aqueous humor and contains two parts: pars plicata (with ciliary processes) and pars plana.

Pars Plicata

Anterior part of the ciliary body rich in ciliary processes that secrete aqueous humor.

Pars Plana

Posterior part of the ciliary body that interfaces with the vitreous.

Major Arterial Circle of the Iris (MAC)

Arterial circle formed by anastomosis of long posterior and anterior ciliary arteries supplying the iris.

Circle of Zinn (annulus of Zinn)

Dense ring of fibrous tissue at the posterior aspect of the orbit from which the recti muscles originate.

Ophthalmic artery

Main arterial supply to the eye; gives rise to many orbital and ocular arteries.

Central Retinal Artery

End artery supplying the inner retina; blockage causes irreversible blindness.

Choroid

Vascular layer between sclera and retina with four sublayers: suprachoroid, stroma, choriocapillaris, Bruch’s membrane.

Choriocapillaris

Fenestrated capillaries that supply outer retina; lies in the choroid.

Bruch’s membrane

Five-layer membrane between the choriocapillaris and the retinal pigment epithelium.

Lacrimal gland

Gland producing aqueous tear layer; located in the superior temporal orbit with orbital and palpebral parts.

Glands of Krause & Wolfring

Accessory lacrimal glands located in the conjunctival fornix and palpebral conjunctiva; contribute basal tear secretion.

Glands of Moll and Zeis

Glands associated with eyelashes; Moll = sweat glands, Zeis = sebaceous glands.

Meibomian glands

Sebaceous glands located in the tarsal plates that secrete the lipid (lipid) layer of the tear film.

Tear Film layers

Three layers: lipid (outer), aqueous (middle), mucin (inner) that create a stable tear film.

Tear Drainage pathway

Tears drain via puncta (upper/lower), canaliculi (vertical then horizontal), lacrimal sac, nasolacrimal duct to the nasal cavity; Hasner’s valve at entry.

Blink mechanisms

Involuntary spontaneous blinking; reflex blinking (dazzle, menace, auditory) and voluntary blinking; role in tear distribution.

Conjunctiva

Thin mucous membrane covering sclera (bulbar) and lining eyelids (palpebral); forms fornices and houses goblet cells.

Conjunctival fornix

Junction where palpebral and bulbar conjunctiva meet; allows tear film movement.

Sclera

Outer protective coat; supports eyeball; contains episclera and lamina fusca; relatively avascular.

Scleral layers

Three layers: episclera, scleral stroma, lamina fusca (inner sclera).

Vitreous humor

Transparent gel filling the posterior cavity; maintains eye shape and retina position; contains hyaloid canal in fetal development.

Macula & Fovea

Macula is the central retina area; fovea is the center with high cone density for high acuity vision.

Retina layers (10)

From outer to inner: RPE, photoreceptor layer, external limiting membrane, outer nuclear, outer plexiform, inner nuclear, inner plexiform, nerve fiber layer, ganglion cell layer, inner limiting membrane.

Photoreceptors

Rods (night vision) and cones (color/day vision); located in outer retina; synapse onto bipolar cells.

RPE (Retinal Pigment Epithelium)

Pigmented cell layer supporting photoreceptors; forms part of the blood-retina barrier and participates in the visual cycle.

Visual pathway

Retina → optic nerve → optic chiasm (nasal fibers cross) → optic tract → lateral geniculate body → optic radiations → primary visual cortex.

Limbus

Border area between cornea and sclera; transition zone in corneal anatomy.

Cornea layers

Six layers: Epithelium, Bowman's layer, Stroma, Dua’s layer, Descemet’s membrane, Endothelium.

Dua’s layer

A recently described posterior corneal layer between stroma and Descemet’s membrane; acellular and strong.

Corneal transparency factors

Arrangement of collagen fibrils, absence of vessels, absence of pigments, and corneal deturgescence.

Aqueous humor production

Produced by nonpigmented ciliary epithelium in the ciliary processes via diffusion, ultrafiltration, and active transport.

Aqueous humor drainage (conventional)

Through trabecular meshwork into Schlemm’s canal and then to episcleral veins; accounts for ~90% of drainage.

Aqueous humor drainage (uveoscleral)

Unconventional outflow through the uvea and sclera; accounts for ~10% of drainage.

Intraocular pressure (IOP)

Pressure inside the eye; normal range approximately 10–21 mmHg.

Glands of Zeis & Moll

Glands associated with eyelashes: Zeis (sebaceous) and Moll (sweat) contributing to tear film and eyelid lubrication.

Glands of Krause & Wolfring

Accessory lacrimal glands in conjunctival fornices and tarsus contributing to basal tear secretion.

Orbital septum

A fascial membrane that houses eyelids and guards the orbit; part of eyelid anatomy.

Tarsal plate

Dense connective tissue within eyelids that houses Meibomian glands.

Puncta lacrimalia

Small openings at eyelid margins that begin tear drainage into canaliculi.

Lacrimal canaliculi

Vertical then horizontal tear drainage channels leading tears to the lacrimal sac.

Lacrimal sac & nasolacrimal duct

Lacrimal sac stores tears; nasolacrimal duct drains tears into the nasal cavity.

Conjunctival goblet cells

Cells in the conjunctiva that secrete mucin to form the mucous layer of the tear film.