Part Ⅳ Sensory Organs SHANDONG UNIVERSITY Liu Zhiyu
Jan 17, 2016
Part Ⅳ
Sensory Organs SHANDONG UNIVERSITY Liu Zhiyu
The Sensory Organs
The receptors may be divided into three kinds: • exteroceptors :receive stimuli such as touch,
temperature, pain, light and sound from the external environment
• interoceptors :pick up information about internal environment
• proprioceptors : 分 receive stimuli from muscles, tendons, joints and ligaments
Sensory organs include
• receptors
• accessory organs
The Visual Organ consist of
eyeball
chapter 1 The Visual Organ
accessory organs of eyeball
Section 1 Eyeball
Ⅰ. Shape of eyeballanterior and posterior poles
anterior pole
posterior pole
Axis of eyeball :a line joining the two poles
Optic axis:a line joining the center of the pupil to the fovea centralis
Equator: an imaginary line encircling the eyeball, midway between anterior and posterior poles
Ⅱ.Structure of eyeball 1. Walls of eyeball
Fibrous tunic of eyeball
Cornea
Sclera
Vascular tunic of eyeball
Retina
Pars iridica retinae
Pars ciliaris retinae
Pars optica retinae
Pars caeca retinae
Iris
Cilliary body
Choroid
Wall of eyeball
(1) Fibrous tunic
(outer layer)
Cornea : anterior 1/6 ; a nonvascular, transparent
portion ; supplied richly by nerves;
because it is curved, the
cornea helps focus light.
Ⅱ
Walls of eyeball
(1) Fibrous tunic
Sclera: posterior 5/6, consists of fibrous
connective tissue having
protection and
surpporting
for eyeball, posteriorly it contineus
with the sheath of optic n.
Sinus venous sclerae
sclera
cornea
sinus venous sclerae :
lies beneath the junction of cornea and sclera, and is irregular circular canal.
cribriform plate of sclera
iris lies the anterior part of the vascular tunic, and is a thin contractile membrane with a central opening, the pupil
(2) Vascular tunic (middle layer):
Wall of eyeball
iridocorneal angle
sphincter pupillae
dilator pupillae
eyeball
a) ciliary ring b) ciliary processes : 60~80, producing aqueous humor
ciliary zonules
Ciliary body : Behind the iris , may be divided into
ciliary muscle ciliary zonules
d)secrete the aqueous humor
eyeball
choroid
Thin, highly vascular in posterior 2/3 of eye Contains brown pigmented cells and dense capillary plexus
function:
Nutrition
Absorb the disperse light
(3) Internal tunic of eyeball—
retina
a. Pars caeca retinae:
b. Pars optica retinae:
pars iridica retinae
pars ciliaris retinae
division: ora serrata
Wall of eyeball
Photoreceptor cells
pigment epithelial layer nervus layer : consist of three layers of cells
The retina consists of two layers:
Cone cell
Rod cell
2) structure:
Pigment cell layer
Cone cell
Rod cell
Wall of eyeball
bipolar cell
ganglion cell whose axons form the optic n. fibers
Pigment cell layer
Cone cells
Rod cells
Bipolar neuron
Ganglion cell
Wall of eyeball
Optic disc (blind spot), located medial to posterior pole of eye, and consists of optic nerve fibers and at where there are central a.and v. of retina
Macula lutea
– Lies lateral about 3.5 mm to optic disc, a shallow depression, and is yellowish in color
Wall of eyeball
– Fovea centralis is an aera of greatest visual acuity and is completely free of blood vessels (concentration of cone cells).
The pigment epithelial layer absorbs light that enter the eyeball preventing backscatter (blurring of vision)
Wall of eyeball
(1) Aqueous humor
1) Chamber of eye :
lies between cornea and
lens, and divided by iris
into:
2. Contents of eyeball
anterior chamber
posterior chamber
Contents of eyeball
2) Aqueous humor
•A clear watery fluid that fills
chamber of eye , secreted by
ciliary body.
Functions
• Helps focus light
• Helps maintain constant pressure in eyeball
• Helps nourish the lens and cornea
secreted by the ciliary body
Production and circulation of aqueous humor:
sinus venosus sclera
posterior chamber pupil
anterior chamber iridocorneal angle
anterior ciliary vein ophthalmic vein
sinus venosus sclera
(2) Lens
position : lis behind the
iris , anterior to the vitreous
body
Contents of eyeball
shape :
Transparent biconvex structure, covered by an elastic transparent capsule which is connected by the ciliary zonules(suspensory lig.)to the ciliary process
Structure:
lens capsule
cortex of lens
lens nucleus
Contents of eyeball
Its shape is changed by the ciliary muscle: for near vision, the ciliary muscle contracts and the lens rounds up,
while for distant vision the lens flattens out, so that the eye may be focused on distant objects
(3) Vitreous body
Consists of colorless,
transparent jelly-like substance in
which there is a meshwork of fine
fibrils, occupies the space
between lens and retina
Helps maintain the shape of eyeball and supports the retina
Contents of eyeball
Cornea
aqueous humor
lens
vitreous body
(4) Refractive media: include
Bend entering light waves and focus them on the
retina
Contents of eyeball
Section2. Accessory organs
①Skin
②subcutaneous adipose
tissue
③musclar layer :
orbicularis oculi
④tarsus : formed
by dense connective
tissue (tarsal glands)
⑤ palpebral conjunctiva
Ⅰ. Eyelids: upper and lower , consist of 5 layers,
3 parts:• Palpebral conjunctiva : lining inner surface of eyelids; • Bulbar conjunctiva : lining anterior part of sclera; •
Ⅱ.Conjunctiva :
thin mucous membrane
Accessory organs of eye
Conjunctival fornix (superior and inferior):
the reflected part of the conjunctiva from the superior and inferior eyelids onto the eyeball. Conjunctival sac
Accessory organs of eye
Ⅲ.Lacrimal apparatus
1. Lacrimal gland :
2. Lacrimal passages :
lacrimal punctum: on each eyelid margin near medial angle
lacrimal ductules : in each lid, pass medially, join and enter lacrimal sac
Lacrimal sac : in fossa for lacrimal sac, opening into nasolacrimal duct
Nasolacrimal duct : opening into inferior nasal meatus
Accessory organs of eye
Ⅳ.Extraocular m. : 7 levator palpebrae superioris: elvates the upper eyelid.
Obliquuses : 2
Superior obliquus
Inferior obliquus
Rectuses: 4 superior rectus
inferior rectus
medial rectus
lateral rectus
Muscle Action N. supply
levator palpebrae superioris elvates upper eyelid Ⅲ
Superior rectus turns eyeball superomedially Ⅲ
Inferior rectus turns eyeball inferomedially Ⅲ
Medial rectus turns the eyeball medially Ⅲ
Lateral retus turns the eyeball laterally Ⅵ
Superior obliquus turns eyeball inferolaterally Ⅳ
Inferior obliquus turns eyeball superolaterally Ⅲ
Accessory organs of eye
Accessory organs of eye
Accessory organs of eye
Ⅴ. Connective Tissues in the Orbit
1. adipose body of orbit lies between sheath of eyeball and the orbit acts as a protective cushion and shock sorber for the eyeball
2. orbital fasciae
a. periorbita
b. fascial sheath of eyeball
c. sheath of ocular muscles
d . orbital septum
Ⅰ. Vessels of eye 1. Artery
(1)Ophthalmic a.: Arises from the internal carotid a.
Branches: 1) central a. of retina
Enters optic nerve, passes toward the optic disk and then fans out to supply the retina
Section 3. The vessels and nerves of eye
1) central a. of retina
branches:
The vessels and nerves of eye
superior nasal arteriole of retina inferior nasal arteriole of retina superior temporal arteriole of retina inferior temporal arteriole of retina
3) long posterior ciliary a .
;
4) anterior ciliary a.
2) short posterior ciliary a.:
Choroidal artery
The vessels and nerves of eye
Ⅱ.Vein
(1 ) central v. of retina
(2 ) vortex vein
(3 ) anterior ciliary veins
(4 ) Ophthalmic v.
a)Superior ophthalmic v.
b) Inferior ophthalmic v
The vessels and nerves of eye
optic nerve: oculomotor n. trochlear n. abducent n.
Ⅲ.Nerves
ophthalmic n.
facial n.
The vessels and nerves of eye
inferior temporal arteriole of retina
superior nasal arteriole of retina
inferior nasal arteriole of retina
superior temporal arteriole of retina
Ciliary Processes
Sphincter PupillaeDilator Pupillae
Sinus venosus sclerae
ciliary zonule
Ciliary Muscle Iridocorneal angle
Lens
chapter14 The Visual Organ
aqueous humor lens vitreous body
Eyeball
accessory organs of eyeball
fibrous tunic :
vascular tunic :
retina
walls
composition
iris
ciliary body
choroid
cornea sclera
choroidal part: pars opticaretinae
pars ciliaris
pars iridiacpars caeca retinae