Eye (sense) Flashcards
What three tunics/layers compose the wall of the eye?
fibrous tunic, vascular tunic, and neural tunic
Fibrous tunic
Tough fibrous superficial layer of the eye
*Sclera & cornea
Sclera
- fibrous tunic
* white of the eye, dense CT
Cornea
- fibrous tunic
* Clear anterior portion of the eye
Vascular tunic (uvea)
middle layer of the eye rich with blood vessels
*Choroid, ciliary body and iris
Choroid
- Vascular tunic
* Pigmented layer prevents reflection of light that would blur an image
Ciliary body
- Vascular tunic
- Ring of smooth muscle (ciliary muscles) attached to the lens by suspensory ligaments
- controls shape of the lens
Iris
- Vascular tunic
- Smooth muscle which controls the diameter of the pupil
- circular pupillary constrictor muscles and radial pupillary dilator muscles
Circular pupillary constrictor muscles of iris
Stimulated by parasympathetic efferent fibers
Radial pupillary dilator muscles of iris
Stimulated by sympathetic efferent fibers
Neural tunic (retina)
deepest layer of the eye, extends anteriorly to the posterior margin of the ciliary body
*portion of the eye where an image is formed
Pigmented epithelium
- neural tunic
* most superficial layer of neural tunic epithelial cells contain melanin granules to prevent reflection of light
Photoreceptor layer
- neural tunic
* located just deep to pigmented epithelium, contains photoreceptor cells that detect light
Rods
photoreceptors sensitive to broad wavelength range providing black and white vision
Cones
photoreceptors sensitive to narrow wavelength range providing color vision
Bipolar neuron layer of retina
layer of retina deep to the photoreceptors, relays info from rods and cones to retinal ganglion
Retinal ganglion neuron layer of retina
deepest layer of retina, contains large neurons that extend axons through the optic nerves and optic tracts
Optic disc
location where axons of retinal ganglion neurons exit the eye, creates a blind spot in the visual field because there are no photoreceptors in this region
Fovea centralis
small pit in the center of the macula lutea which contains the greatest concentration of cones, sharpest vision
Anterior cavity of the eye
In front of the lens, contains aqueous humor which provides nutrients to the lens and cornea
Anterior chamber of the anterior cavity
anterior to iris
Posterior chamber of the anterior cavity
posterior to iris, anterior to lens
Lens
Clear biconvex disc shaped structure that can change its convexity (curvature) to focus light from an object close to the face (near point accommodation)
Posterior cavity of the eye
Posterior to the lens, filled with jelly like vitreous humor
Palpebrae
Eyelids, protects and covers the eye
Eyelashes
keep debris out of the eyes
Conjunctiva
mucous membrane lining inner surface of the eyelids and the anterior surface of the eye
Palpebral conjunctiva
mucous membrane covering the inside of eyelids
bulbar conjunctiva
mucous membrane covering the sclera of the eye
lacrimal gland
found on the superior lateral surface of the eye, produces tears
lacrimal sac
collects tears
nasolacrimal duct
drains tears from the lacrimal sac into the nasal cavity
Superior rectus
directs gaze superiorly, excited by CNIII (oculomotor nerve)
Medial rectus
directs gaze toward midline, excited by CNIII (oculomotor nerve)
Inferior rectus
directs gaze inferiorly, excited by CNIII (oculomotor nerve)
lateral rectus
directs gaze away from midline, excited by CNVI (abducens)
Superior oblique
rotates the superior aspect of the eye toward the midline, excited by CNIV (Trochlear nerve)
Inferior oblique
rotates the inferior aspect of the eye toward the midline, excited by CNIII (oculomotor nerve)
Describe the visual pathway from the photoreceptors to primary visual cortex
Photoreceptors>bipolar neurons of the retina>retinal ganglion neurons>optic nerve>optic chiasm>optic tract>Thalamus>occipital lobe (primary visual cortex)
