Chapter 1: Anatomy And Physiology Flashcards
Refractive power of the average cornea
43.00 Diopters
Refractive power of Crystalline Lens
17.00 Diopters
Transparent living structures through which light passes.
The tear layer, cornea, aqueous humor, crystalline lens, and vitreous humor
Three Chambers of the eye:
Anterior Chamber- Space between the back of the Cornea and the Iris
Posterior Chamber- Space between Iris and Crystalline Lens
Vitreous Chamber- Space between Crystalline Lens and the Retina
What are the three layers of the eye and their purpose?
Fibrous Tunic- Made up of dense connective tissue, provides attachment for the muscles that control eye movement, and consists of the sclera and the cornea
Vascular Tunic- Consists of the iris the choroid in the ciliary body and is responsible for nourishment. Formed from back to front
Nervous/ Neural Tunic- The inner layer of photo receptors and neurons which consist of the retina responsible for image perception
What are Rods?
Rods are special photo (light) receptors. Rods let us see at night and dimly lit rooms. There are approximately 120 million rods spread towards the outside of the retina. They help with night vision, peripheral vision and black & white.
What are Cones?
Cones are light receptors located near the center of the MACULA. Highest concentration found near FOVEA. Help with detail, colors and day time vision.
What are the 5 layers of the Cornea?
Epithelium Bowman’s Membrane Stroma Descemet’s Membrane Endothelium
What are the Six Extraocular Muscles?
How do they rotate the eye?
Superior Oblique- Eye rolls and looks down and to the side. Attaches under the superior rectus, passes through a bony spur known as the trochlea and then follows the path of the superior rectus.
Superior Rectus- Eye looks up. Attaches directly to the top of the eye and runs straight back.
Medial Rectus- rotates the eye medially or in towards the nose. Attaches directly to the side of the eye and runs straight back.
Inferior Rectus- Eye looks down. Attaches directly to the bottom of the eye and runs straight back.
Inferior Oblique- Eye rolls, looks up and to the side. Attaches along the lateral side of the eye and runs under the eye passing over the inferior rectus and attaches medially.
Lateral Rectus- Rotates laterally or out towards the ear. Attaches directly to the side of the eye and runs straight back.
How many muscles does the Iris have?
What do they do?
The Dilator muscle opens the Iris allowing more light in.
The Sphincter muscles closes the Iris constricting light.
The Iris has the ability to change the pupil size from 2 mm to 8 mm
What is the Palpebrae and what is it’s purpose?
The palpebrae are another term for the eyelids. They help control the amount of light that enters the eye, distributes tears across the ocular surface, and provide protection to the eye.
What is the Crystalline lens?
A transparent colorless body suspended in the front part of the eyeball, between aqueous and the vitreous, the function of which is to bring light rays to focus on the retina. Responsible for accommodation.
index of refraction = 1.42
17.00 Diopters
What are the Medial and Lateral Canthi?
The Canthi are the points where the eyelids meet.
Medial Canthus- The point where the upper and lower eyelids me near the nose. “The corner of your eye.”
Lateral Canthus- The point where your upper and lower eyelid meets towards your ear.
What are Meibomian Glands?
The Meibomian glands are located along the inner margin of the eyelids. The glands secrete a liquid (Meibum) that keep the eyelids from sticking together. These secretions make up part of the tear film.
Lacrimal Gland:
The lacrimal gland is located inside the upper lateral orbit of the eye.
It is the gland that produces the bulk of the tears. It is located above the lateral canthus in a depression in the bone that surrounds the eye (Lacrimal Fossa)
Secretes the aqueous layer of tear film.
Inflammation of lacrimal gland = Dacryoadenitis
