Download Aesthesiology (Sense organs)

Aesthesiology (Sense organs)
Sense organs include:
1. Eye : Organ for vision
2. Ear: Organ for hearing
3. Nose: organ for smell
4. Skin: Sense for touch, heat and cold.
5. Tongue: Sense for taste.
EYE
Eye in general consisting of:
(1) Eye ball and
(2) Accessory structures
Major Layer and Chambers of eye Ball
Eye ball consisting of three layer:
(1)Fibrous tunic: Sclera and Cornea
(2)Vascular layer: Ciliary body, Ciliary process,
Iris.
(3) Nervous layer: Retina.
Chambers of the eye ball:
(1)Anterior chamber: In between cornea and iris.
(2)Posterior chamber: In between iris and lens
(3)Vitreous body: In between lens and retina.
Accessory Structure of Eye Ball
1. Muscles of the eye ball:
(a) 4 rectus muscles: Dorsal rectus, Ventral rectus
Lateral rectus and Medial Rectus
(b) 2 Oblique: Dorsal oblique and ventral oblique
(c) Retractor oculi
2. Periorbital fat.
3. Nerves: Optic, Occulomotor, Trochlear, Opthalmic, and
Abducent.
4. Optic artery and vein.
5. Lymphatic channels, and,
6. Lacrimal apparatus: Lacrimal gland, duct, sac, naso-lacrimal duct.
7. Eye lid: Upper and lower eye lid.
8. Conjunctiva: Palpebral and bulbar conjuctiva.
Structure of the Eye Ball
Fibrous Tunic of Eye Ball
 The fibrous tunic is the outer most layer of the eye ball,
gives the shape of the eye ball and consist of dense
collagenous fiber. The fibrous tunic consist of:
Sclera: Posterior three-quarter of the eye ball, whitish
and tough.
 Cornea: Anterior transparent part is the cornea.
Sclera and cornea meet anteriorly at corneo-scleral
junction or limbus.
Vascular Layer of the Eye Ball
The vascular layer consist of three layers:
(1) Choroid (2) Ciliary body and (3) Iris
Function: Blood supply, suspension and regulation of the shape of the
lens, regulation of the size of the pupil, and production of aqueous
humor.
Choroid: It is pigmented, highly vascular layer and envelop the posterior
part of the eye-ball. Near the optic papilla it consist of half moon-shaped
area the tapetum.
Ciliary body: Thickest middle segment between choroid and iris. It consist
of ciliary process and zonular fiber. Ciliary process is responsible for
formation of aqueous humor and zonular fiber connects with the lens and
controls shape of the lens.
Iris: It is the anterior most part of the vascular layer and act as a muscular
diaphragm between cornea and lens. It forms the pupil.
Nervous Layer of the Eye Ball
It is the innermost layer of the eye ball where
light reflect and forms images. It consist of ten
histological layers. Optic nerve innervates into
this layer.
Inner Structure of Eye Ball (Lens and
Chambers)
Lens of eye ball: The lens is a transparent biconvex
structure and suspended in the eye by zonular fibers. The
posterior surface is more convex than the anterior. The
convexity changes for the accommodation of light. It
receives nutrition from aqueous and vitreous humor.
Eye has three chambers: (a) Anterior (b) Posterior and
(c) Vitreous Chamber.
(a) Anterior Chamber: It is bounded anteriorly by cornea
and posteriorly by Iris and lens. It is communicated to
the posterior chamber through the pupil.
Posterior Chamber and Vitreous
Chamber
Posterior chamber: It is bounded anteriorly by iris and
ciliary body and posteriorly by lens. It is filled up
with aqueous humor.
Vitreous Chamber: It is bounded anteriorly by lens and
ciliary body. The rest of the vitreous chamber is
enclosed by the retina. It is filled by viscous jelly like
mass called vitreous humor/vitreous body.
Chambers and Lens of Eye Ball
Formation, circulation and
drainage of aqueous humor:
Sclera
Ant. Cham.
Posterior
Chamber Active secretory process from the
Cornea
Lens
Ciliary Aqueous humor circulate throughProcess out the posterior chamber
Iridocorneal
Junction
epithelium of the ciliary body
Pass through the pupil
Aqueous humor enters into the anterior
chamber and circulate throughout it
Finally drain through the iridocorneal
junction into venous circulation
Formation, Circulation and Drainage of
Aqueous Humor
Aqueous humor produced by an active secretory process
from the epithelium of the ciliary body. It is clear and
colorless fluid containing several electrolytes, amino
acids, glucose and ascorbic acid.
It flows from posterior chamber to the anterior chamber
through the pupil and drains through the iridocorneal
junction into the venous plexus. Impairment of the flow
and drainage of aqueous humor results in Glaucoma. It
increases intraocular pressure resulting retinal atrophy
and blindness. We can diagnose it by the protrusion of
the eyeball.
Function of aqueous humor: It provides nutrition to the
cornea and lens.
Lacrimal apparatus
Lacrimal sac
Lacrimal gland &
Excretory duct  Lacrimal
gland (tear gland)
secretes lacrimal fluid, excrete
Lacrimal into the conjunctival sac. From
canaliculi here through lacrimal canaliculi
Nasolacrimal duct
into the lacrimal sac and finally
via the nasolacrimal duct drains
into the nasal cavity.
Composition: Water, salt and
Few electrolytes.
 Any defect in the secretory
Mechanism leads to “dry eye
Syndrome”.