Eyes Anatomy & Physiology - Vocabulary Flashcards

VOCABULARY flashcards covering external structures, lacrimal apparatus, eye layers, chambers, retina, and visual pathways from the notes.

Eyebrows

Hair-covered ridges above the eyes that help protect and shade the eyes.

Eyelashes

Hairs along the edge of the eyelids that trap dust and debris and protect the eye.

Eyelids (Palpebrae)

Movable folds that protect the eyeball; lined with conjunctiva.

Conjunctiva

Mucous membrane stretching from the eyelids to cover the anterior sclera.

Palpebral fissure

The opening between the upper and lower eyelids.

Canthus (medial and lateral)

The inner (medial) and outer (lateral) corners where the eyelids meet.

Levator palpebrae superioris

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

Superior rectus muscle

Eye muscle that elevates the eye; innervated by CN III.

Inferior rectus muscle

Eye muscle that depresses the eye; innervated by CN III.

Superior conjunctival fornix

The upper recess formed where the conjunctiva folds between lid and eyeball.

Inferior conjunctival fornix

The lower recess formed where the conjunctiva folds between lid and eyeball.

Tarsal (Meibomian) gland

Oil-secreting glands in the tarsal plate; blockage can cause chalazion.

Tarsal plate

Dense connective tissue framework within the eyelid that supports its shape.

Cornea

Transparent, avascular, anterior part of the eye that refracts light.

Bulbar conjunctiva

Conjunctival portion covering the eyeball (scleral surface).

Lacrimal apparatus

Structures that produce and drain tears: lacrimal glands, canals, sacs, and nasolacrimal ducts.

Lacrimal gland

Gland that secretes tears; almond-sized.

Lacrimal canals (puncta)

Tiny channels at the eyelid margins that drain tears into the lacrimal sac.

Lacrimal sac

Tearduct reservoir located in a groove in the lacrimal bone.

Nasolacrimal duct

Tube that drains tears from the lacrimal sac into the inferior meatus of the nose.

Lacrimal caruncle

Small fleshy mound at the medial corner of the eye.

Puncta

Minute openings at the eyelid margins beginning tear drainage.

Lacrimal ducts

Ducts that transport tears toward the lacrimal sac.

Orbicularis oculi

Circular facial muscle surrounding the eye; closes the eyelids.

Iris

Colored portion of the eye; regulates pupil size via sphincter and dilator muscles.

Sphincter pupillae

Muscle in the iris that constricts the pupil; mostly parasympathetic control.

Dilator pupillae

Muscle in the iris that dilates the pupil; controlled by sympathetic fibers.

Ciliary muscle

Smooth muscle altering lens shape for accommodation; part of the uveal tract.

Zonule fibers

Suspensory ligaments attaching the ciliary body to the lens; adjust lens shape.

Lens

Transparent structure whose curvature focuses light on the retina; changes during accommodation.

Accommodation

Process of increasing optical power by lens thickening for near vision.

Ciliary processes & epithelium

Tubular outgrowths that secrete aqueous humor into the posterior chamber.

Choroid

Vascular, pigmented layer between retina and sclera; provides blood supply and absorbs excess light.

Aqueous humor

Clear fluid formed by the ciliary epithelium; fills anterior and posterior chambers and drains via Schlemm's canal.

Canal of Schlemm (Scleral venous sinus)

Venous sinus that drains aqueous humor from the eye back into the bloodstream.

Posterior chamber

Space behind the iris and in front of the lens; part of the aqueous humor system.

Anterior chamber

Space in front of the iris and behind the cornea; filled with aqueous humor.

Vitreous body

Gel-like substance filling the posterior segment behind the lens.

Sclera

White, tough outer layer; protective; analogy to dura mater.

Scleral venous sinus

Canal of Schlemm; drains aqueous humor to venous circulation.

Retina

Inner sensory layer that converts light into neural signals; contains photoreceptors (rods, cones,) and three neuronal layers.

Photoreceptors

Rods and cones; transduce light into neural signals.

Rods

Photoreceptors highly sensitive to light; important for night vision; low acuity; not in the fovea.

Cones

Photoreceptors for color and high-acuity vision; less sensitive to light; three types for different wavelengths.

Fovea

Central retinal area with the highest visual acuity; cones-dense.

Foveola

Center of the fovea; smallest pit with highest acuity.

Bipolar cells

Retinal neurons that relay signals from photoreceptors to ganglion cells.

Ganglion cells

Retinal neurons whose axons form the optic nerve.

Optic nerve (CN II)

Nerve transmitting visual information from retina to brain; composed of retinal ganglion cell axons.

Optic chiasm

X-shaped crossing of nasal retinal fibers; partial decussation of visual information.

Optic tract

Bundle of fibers after the chiasm carrying information to the LGN.

Meyer’s loop

Part of the optic radiation in the temporal lobe dealing with the superior visual fields.

Lateral geniculate nucleus (LGN)

Thalamic relay for visual information to the visual cortex.

Optic radiation

Fibers from LGN to the visual cortex; includes Meyer's loop for superior field.

Visual cortex

Occipital lobe region that processes visual input.

Convergence

Movement of both eyes toward each other to maintain single binocular vision.

Pupillary light reflex

Pupil constriction in response to light; parasympathetic control via CN III pathways.

Pupillary dilation

Pupil enlargement in response to sympathetic activity.