LAB #10 - Vision 1 (Eye Anatomy)

Chapter 15 – Section 15.1, 15.4

Palpebrae 

Eyelids

Tarsal glands

Sebaceous glands in the eyelids that produce an oily secretion that lubricates the eyes.

Conjunctiva

Thin mucous membrane with blood vessels and glands (secrete watery mucus)

Palpebral conjunctiva

lines eyelids

Bulbar conjunctiva

covers anterior surface (sclera) of eye

Lacrimal Apparatus

The lacrimal gland and the ducts that drain lacrimal fluid in to the nasal cavity

Lacrimal gland

Secretes tears into the lacrimal excretory ducts from the lateral end of the eye.

Lacrimal punctum (puncta)

Where tears enter the lacrimal canaliculi after flowing across the eye

Lacrimal sac

Where tears collect from the lacrimal canaliculi and empty into the nasolacrimal duct to the nasal cavity.

Extrinsic eye myscles

Skeletal muscles that control eye movement

Lateral rectus

Moves eye laterally; Abducens (VI)

Medial rectus

Moves eye medially; Oculomotor (III)

Superior rectus

Elevates eye and turns it medially; Oculomotor (III)

Inferior rectus

Depresses eye and turns it medially; Oculomotor (III)

Inferior oblique

Elevates eye and turns it laterally; Oculomotor (III)

Superior oblique

Depresses eye and turns it laterally; Trochlear (IV)

Fibrous layer

Avascular; Sclera, cornea, scleral venous sinus (canal of Schlemm)

Sclera

White opaque portion of the fibrous layer of the eyeball

Cornea

Transparent anterior portion of the eyeball

Scleral venous sinus

A venous channel that encircles the eye at the junction of the cornea and sclera; reabsorbs aqueous humor into the venous blood.

Vascular layer (Uvea)

Choroid, Ciliary body, Iris, Pupil

Choroid

A blood vessel-rich membrane that forms the posterior five-sixths of the vascular layer of the eye; nourishes all eye layers.

Ciliary body

Thickened ring of tissue that encircles the lens; consists of the ciliary muscles, ciliary processes, and ciliary zonules.

Ciliary muscles

Smooth muscles that control the tension of ciliary zonules.

Ciliary processes

Folds on the posterior surface of the ciliary body that secrete the aqueous humor

Ciliary zonules

Suspensory ligaments that extend form the ciliary muscle to the lens to support the shape of the lens.

Iris

The colored part of the eye, positioned between the cornea and the lens, that regulates pupil size; vascular, pigmented.

Dilator pupillae

Radial smooth muscle fibers that cause pupil dilation.

Sphincter pupillae

Circular smooth muscle fivers that cause pupil constriction

Pupil

Opening in the center of the iris through which light enters the eye.

Inner layer (Retina)

Pigmented and neural layers of the eye that convert light into nerve signals.

Pigmented epithelium

The outer layer of the retina, consisting of a single layer of pigment cells that absorb light and prevent it from scattering in the eye.

Neural Layer

The transparent inner layer of the retina that is composed of photoreceptors (rods and cones), bipolar cells, ganglion cells, and horizontal and amacrine cells.

Optic nerve

Axons of ganglion cells; Cranial Nerve II

Optic Disc

Blind spot in the eye where there are no photoreceptors and the optic nerve and central artery and vein enter and exit the eye.

Macula lutea

Yellow region of the eye that contains mostly cones (fovea centralis)

Fovea centralis

Tiny pit in the center of the macula lutea that contains only cones where other retinal structures are pushed aside to provide detailed color vision; region of greatest visual acuity.

Ora serrata

Anterior margin of the retina with the ciliary body.

Central artery and vein

Blood vessels that enter and leave the eye through the center of the optic nerve to serve the inner two-thirds of the neural layer of the retina.

Lens

Crystallin protein; held in place by ciliary zonules

Anterior segment

Internal chamber of the eye that extends from the cornea to the lens; filled with aqueous humor; made up of the anterior and posterior chambers.

Anterior chamber

Region of the eye between the cornea and the iris.

Posterior chamber

Region of the between the iris and the lens.

Aqueous Humor

Filtrate of blood from ciliary processes that fills the anterior segment (anterior/posterior chambers).

Posterior segment

Internal chamber of the eye that extends from the lens to the retina, filled with vitreous humor.

Vitreous Humor

Clear gelatinous substance the fills the posterior segment of the eye; formed before birth.

Outer segment

Receptive regions of photoreceptors that are embedded in the pigmented layer of the retina; stacks of discs with visual pigments.

Rods

Rhodopsin (opsin + retinal)

Cones

3 different forms of photopsin + retinal

Primary Visual Pathway

Optic nerve → Optic Chiasm → Optic tracts → LGN → V1

Superior Colliculus Pathway

Optic Nerves → Optic Chiasm → Optic tracts → Superior Colliculus

For visual reflexes (coordinate head and eye movements with visual stimuli)