Distinct receptor cells that are confined to the head region and are highly localized; housed in complex sensory organs or in distinct epithelial structures.
Special sensory receptors
The majority of this is enclosed and protected by a cushion of fat and the walls of the bony orbit.
Name the 5 accessory structures of the eye.
extrinsic eye muscles
Help shade the eyes from sunlight and prevent prespiration from reaching the eye. Depressed by the contraction of the orbicularis, moved medially by the corrugator.
These are seperated by the palpebral fissure and meet at the medial and lateral commisures.
These contain sebaceous and sweat glands that produces the whitish, oily secretion, Sandman's eyesand.
Connective tissue sheets that support eyelids internally.
Modified sebaceous glands that produce an oily secretion that lubricates the eyelid and eye, preventing stickage.
More typical sebaceous gland that lies between the hair follicles of the eyelash.
Transparent mucous membrane that lines the eyelids
The transparent mucous membrane that reflects over the anterior surface of the eyeball. Covers only the white of the eyes.
Its major function is to produce a lubricating mucous that prevents eyes from drying out.
Consists of the lacrimal gland and ducts that drain excess lacrimal secretions into the nasal cavity.
These muscles originate from the bony orbit and insert into the outer surface of the eyeball.
Extrinsic eye muscles
Name the four rectus muscles that originate from the common tendinous ring.
medial rectus muscles
The superior oblique muscle of the eye passes through this fibrocartilaginous loop suspended from the frontal bone.
This oblique eye muscle rotates the eye downward and somewhat laterally.
Superior oblique muscle
This oblique eye muscle rotates the eye up and laterally.
Inferior oblique muscle
The two poles of the eyeball.
The three layers, or tunics, that compose the wall of the eyeball.
The two regions of the fibrous layer of the eyeball.
Forms the bulk of the fibrous layer of the eyeball, white and opaque. Provides sturdy anchoring for extrinsic eye muscles.
Forms a window that lets light enter the eye; light bending apparatus. Transparent bulge of the fibrous layer of eyeball.
These help maintain clarity of the cornea by keeping water content of cornea low.
The three regions of the pigmented vascular layer.
The blood-vessel rich, dark brown membrane that forms the posterior five-sixths of the vascular layer. Provides nutrients to all of the eye's layers. The pigment helps absorb light. Incomplete where the optic nerve leaves the eye.
Anteriorly, the choroid becomes this thickened ring of tissue that encircles the lens. Important in controlling lens shape.
The visible colored part of the eye that lies between the cornea and the lens.
The round central opening of the iris that lets light enter the eye.
The contraction of these muscles cause the pupil to constrict in close vision and bright light.
The contraction of these muscles cause the pupils to dilate in distant vision and dim light.
Innermost layer of the eye wall that is composed of the pigmented layer and the transparent neural layer.
This originated as an outpokceting of the brain and contains millions of photoreceptors that transduce light energy.
The three main types of neuron of the neural layer of the retina.
Where the optic nerve exits the eye is called this. Also called the blind spot because it lacks photoreceptors.
The two types of photoreceptors found in the retina.
Our dim-light and peripheral vision photoreceptors. More numerous, more sensitive to light, but fuzzy, colorless vision.
These type of photoreceptors operate in bright light and provide high acuity color vision.
This clear gel that fills the posterior segment of the eye 1) transmits light, 2) supports the posterior surface of the lens and holds the neural retina against the pigmented layer, and 3) contributes to intraocular pressure.
This clear fluid, similar to blood plasma, fills the anterior segment and drains continually and is in constant motion. Supplies nutrients and oxygen to the lens and cornea and to some cells of the retina.