Special Senses – Vision

Vocabulary flashcards covering anatomy and physiology of the eyeball, associated structures, and basic clinical terms from the lecture notes.

Special senses

Senses located only in the head: vision, smell, taste, hearing, and sense of head movement.

General senses

Sensations distributed throughout the body such as temperature, pain, and mechanical stimuli.

Eyeball

The globe of the eye consisting of three tunics and internal cavities; works with accessory structures for vision.

Iris

Colored part of the eye containing melanin; smooth muscle controls pupil diameter.

Pupil

Opening in the iris that allows light to enter the eye.

Sclera

Dense irregular connective tissue forming the white of the eye; protects and maintains shape.

Cornea

Transparent, avascular modification of the fibrous tunic that helps focus light onto the retina.

Extrinsic eye muscles

Skeletal muscles attached to the eyeball that produce voluntary eye movements.

Conjunctiva

Transparent mucous membrane covering the anterior sclera and inner eyelids; keeps the eye surface moist.

Conjunctivitis

Inflammation of the conjunctiva, commonly called “pink eye.”

Lacrimal gland

Gland that produces tears for lubrication and protection of the eye.

Fibrous tunic

Outermost layer of the eye wall comprising the sclera and cornea.

Vascular tunic

Middle layer of the eye providing metabolic support; includes iris, choroid, and ciliary body.

Choroid

Posterior part of the vascular tunic containing melanin to prevent light scattering.

Ciliary body

Ring of smooth muscle that anchors the lens via suspensory ligaments and changes lens shape for focusing.

Suspensory ligaments

Elastic fibers connecting the ciliary body to the lens, enabling lens shape adjustment.

Lens

Transparent, avascular structure that focuses light onto the retina; opacity leads to cataracts.

Cataracts

Clouding of the lens that impairs vision.

Nervous tunic (Retina)

Innermost layer that detects light and converts it to neural signals.

Pigmented layer of retina

Melanin-containing layer that absorbs stray light to prevent scattering.

Photoreceptors

Rods and cones that convert light into electrical signals.

Rods

Photoreceptors detecting gray tones; function in low light.

Cones

Less abundant photoreceptors responsible for color vision and high-resolution images.

Bipolar cells

Retinal neurons that integrate input from multiple photoreceptors.

Ganglion cells

Retinal neurons whose axons form the optic nerve and transmit visual information to the brain.

Optic nerve (CN II)

Bundle of ganglion cell axons that carries visual signals from the eye to the brain.

Optic disc

Site where the optic nerve exits the eyeball; lacks photoreceptors creating a blind spot.

Macula lutea

Central region of the retina with high cone density, providing sharp vision.

Fovea centralis

Depression in the macula lutea with the highest cone density and best visual resolution.

Anterior cavity

Space between the lens and cornea containing aqueous humor.

Posterior cavity

Space between the lens and retina filled with vitreous humor.

Aqueous humor

Thin fluid in the anterior cavity that nourishes the lens and cornea.

Canal of Schlemm (venous sinus)

Channel that drains aqueous humor into veins; blockage can lead to glaucoma.

Glaucoma

Condition of increased intraocular pressure due to impaired aqueous humor drainage, risking optic nerve damage.

Vitreous humor

Gel-like substance in the posterior cavity that supports the lens and retina.

Anterior chamber

Subdivision of anterior cavity between the cornea and iris.

Posterior chamber

Subdivision of anterior cavity between the iris and lens.

Ophthalmoscopy

Clinical examination of the interior of the eye, notably the optic disc and retina.