SPECIAL SENSE ORGANS - University of Nairobi · filled with the gel like Vitreous Humor. ... (N....
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Transcript of SPECIAL SENSE ORGANS - University of Nairobi · filled with the gel like Vitreous Humor. ... (N....
SPECIAL SENSE ORGANS
Organs/tissues that enable the animalto interact
with the environment.
i. The eye- organ of vision.
ii. The ear - organ of hearing and balance
iii. Olfactory epithelium - detection of smell.
iv. Vomeronasal organ -detection of pheromones
v. The gustory organ - taste buds, detect taste
vi. Diffuse receptors in the skin- detect temperature,
pressure, pain, touch
THE EYE
The eye is the organ of vision and is normally paired
in animals. The components of the eye may be
divided into the main structures and accessory
structures.
:
The main structures:
• the eyeball
• the optic nerve.
The accessory structures:
i the orbit, orbital fascia and muscles.
ii eyelids
iii conjuctiva.
iv lachrimal apparatus
THE ORBIT
The eyeball is contained in an osseous cavity known as
the orbit, which is formed by the following bones:
i frontal
ii lachrimal
iii zygomaticus
iv temporal
v palatine
vi maxilla
vii sphenoid.
The eye orbit contains muscles, nerves and vessels
of the eye. It is closed in the horse, buffalo, sheep,
deer, , cattle but open in rabbits and dogs. The
position of eyes depends on the environmental
needs of an animal. In carnivores, the eyes assume
a frontal position while in herbivores they are more
lateral.
THE EYE BALL (BULBOUS OCULI)
consists of 3 concentric tunics (coats, layers):
i) The fibrous tunic Sclera + Cornea.
ii) The vascular tunic choroi d+ ciliary body + iris.
iii) The nervous tunic Retina
Optic Disk
The optic disk is the spot on the retina where the optic
nerve leaves the eye. There are no sensory cells here,
creating a blind spot. Each eye covers for the blind spot
of the other eye and the brain fills in the missing
information
ANTERIOR CHAMBER
The space between the cornea and iris filled with Aqueous Humor.
Aqueous Humor
A water like fluid, produced by the ciliary body, it fills the front of
the eye between the lens and cornea and provides the cornea and
lens with oxygen and nutrients. It drains back into the blood
stream through the canals of schlemm.
Brain
• Vitreous Cavity
• The space between the lens and retina
filled with the gel like Vitreous Humor.
• Vitreous Humor
• The vitreous humor is a jelly like liquid that
fills most of the eye (from the lens back).
Macula - (yellow spot)
This part of the retina is the most sensitive. Its diameter
is only 7 mm or about 1/4 inch. It is responsible for our
central, or reading vision. Without the macula, you would
be blind - Legally Blind that is. People with eye diseases
like Macular Degeneration have vision from poor vision
Fovea - (small pit)
The fovea is an indentation in the center of the macula.
Its diameter is only 1.5 mm or about 1/16 inch. This
small part of our retina is responsible for our highest
visual acuity. It is the center of our central vision.
Cranial nerve Muscle
Oculomotor nerve
(N. III)
Superior rectus muscle Inferior
rectus muscle
Medial rectus muscle
Inferior oblique muscle
Levator palpebrae superior
muscle
Trochlear nerve
(N. IV) Superior oblique muscle
Abducens nerve
(N. VI)
Lateral rectus muscle
Retractor bulbi muscle
1 – upper lacrimal canaliculus
2 – lacrimal caruncle
3 – nasolacrimal duct
4 - gland of the third eyelid
5 – punctum lacrimale
6 – third eyelid
7 – conjuctival fornix
8 - pupil
The iris is composed of stroma (S) and a posterior epithelial
lining (PEL). The sphincter muscle (SM) of the iris is evident
within the stroma. The pigmented posterior epithelial lining
normally extends around the lip of the pupil anteriorly for a
short distance.
The conjunctiva can be divided into three parts. The palpebral
conjunctiva (arrow) lines the posterior surface of the eyelid. The
bulbar conjunctiva (double arrows) extends from the limbus over the
anterior sclera. The bulbar and palpebral conjunctiva converge upon
the conjunctiva of the superior and inferior fornices (triple arrows).
1 – levator palpebrae superioris
2 – 0rbital septum
2‘ – tarsus
3 – obicularis oculi
4 – punta lacrimalia
5 - Cilium, sebaceous glands
6 – tarsal glands
1-dorsal rectus
2-lateral rectus
3- Ventral rectus
4 – medial rectus
5- ventral oblique
6- dorsal oblique
7 - retractor bulbi
6‘ trochleanerve
8 – optic nerve
THE EAR
1) External ear – auris externa
2) Middle ear – auris media
3) Internal ear – auris interna
The ear consists of three parts
The outer ear includes:
•auricle (cartilage covered by skin placed on
opposite sides of the head)
•auditory canal (also called the ear canal)
•eardrum outer layer (also called the tympanic
membrane)
•
The outer part of the ear collects sound. Sound
travels through the auricle and the auditory canal,
a short tube that ends at the eardrum.
The Middle Ear
The middle ear includes:
Eardrum cavity (also called the tympanic cavity)
• Has ear ossicles (3 tiny bones)
•malleus (or hammer) – long handle attached to
the eardrum
•incus (or anvil) – the bridge bone between the
malleus and the stapes
•stapes (or stirrup) – the footplate; the smallest
bone in the body
The Inner Ear
The inner ear includes:
•oval window – connects the middle ear with the inner ear
•semicircular ducts – filled with fluid; attached to cochlea
and nerves; send information on balance and head position
to the brain
•cochlea – spiral-shaped organ of hearing; transforms
sound into signals that get sent to the brain
•auditory tube – drains fluid from the middle ear into the
throat behind the nose
The Middle Ear
HOME // Hearing Health Resource
Center // Anatomy of the Ear // The
Middle Ear
The middle ear includes:
eardrum
cavity (also called the tympanic cavity)
ossicles (3 tiny bones that are attached)
malleus (or hammer) – long handle
attached to the eardrum
incus (or anvil) – the bridge bone
between the malleus and the stapes
stapes (or stirrup) – the footplate; the
smallest bone in the body
Malleus
Head lies in epitympanic recess.
Articulates with incus
Handle attached to TM.
Chorda tympani nerve crosses medial surface of neck.
Base fits into fenestra vestibuli (oval window).
Head articulates with incus
Stapes
Incus
Lies in epitympanic recess.
Head articulates with head of malleus.
Long process articulates with stapes.
Short process connected by ligament to posterior wall