What percent of sensory receptors are in the eye?
70%
how much of the eye is visible
1/6th
eyebrows
accessory structure
Overlie supra-orbital margins of skull. Shade the eyes from sunlight and prevent perspiration from reaching eyes.
-Contraction of Orbicularis Oris OR Oculi and corrugators muscles
eyelids
accessory structure
(Palpebrae), Separated by the palpebral fissure; meet at the medial and lateral commissures of the eye.
-Function: Protect the eyes, Blink 3-7 sec., prevent drying through blinking.ds are supported internally by tarsal plates (connecti
lacrimal caruncle
accessory structure
In medial commissure; ; fleshy elevation that contains sebacceous and sweat glands and produces sandman's eyesand (oily secretion)
tarsal plates
accessory structure
Connective Tissue Sheets, support eyelid
eyelashes
accessory structures
Projecting follicles of which a touch induces reflex blinking.
-Has tarsal glands (in tarsal plates) to secret oily lubrication
rich in nerve endings (hair follicle receptors � unencapsulated); reflex blinking
-contain sebaceious glan
conjunctiva
accessory structure
transparent mucous membrane that lines the eyelids (palpebral conjunctiva) and reflexts over the anterior surface of the eyeball (bulbar conjunctiva)
-bulbar conjunctiva is loose and wrinkled over the sclera and contains small blood ve
tarsal glands
secretors of an oily substance; located in the eyelids
Lacrimal Gland
�In orbit above lateral end of the eye
-Releases lacrimal secretion (tears) as a saline solution.
�As you blink tears are spread downward to the following pathway
-Go through Lacrimal Puncta
-Enter Lacrimal Canaliculi
-Drain into Lacrimal Sac
-Then fall i
lacrimal apparatus
-lacrimal gland is in the orbit above the lateral portion of the eye
-continually releases tears (contains mucus, antibodies, lysozyme)
-tears go to medial commissure and enter the lacrimal cnaliculi via the lacrimal puncta (red dots on medial eyelid)
-te
rectus muscles (extrinsic)
�Originate from annular ring which surrounds optic canal
oblique muscles (extrinsic)
�Move eyeball in vertical plane when the eye is already looking medial
Superior oblique and Inferior oblique (extrinsic)
�rotate eye opposite their name and also laterally.
Superior and inferior recti
�naturally turn the eye medially when they depress and elevate it, thus the superior and inferior oblique muscles are essentially to pull eye laterally
-This counteracts medial pull allowing eye to depress and elevate vertically
extrinsic eye muscles
Originate from the bony orbit and insert into the outer surface of the eyeball; allow the eye to move and maintains shape
-rectus muscles originate from the annular ring (surrounds optic canal) at the back of the orbit and insert on the eyeball
-superior,
lateral rectus innervated by
abducens (VI)
superior innervated by
trochlea (IV)
rest of exterior eye muscles by
oculomotor III