2. Ear
• Organ of hearing
and involved in
balance
• Supplied by 8th
cranial nerve .
• The cochlear part
of the
vestibulocochlear
nerve which is
stimulated by
vibrations
5. • Auricle (Pinna )
Visible part of ear
Composed of fibro elastic cartilage covered
with skin
Helix , fold surrounding the auricle .
Lobule (ear lobe) : Soft part composed of
fibrous and adipose, tissue rich supply of
blood
6. External Acoustic Meatus
• Extend from auricle to tympanic membrane
• There are numerous ceremonious glands and
hair follicles associated sebaceous glands
• Secrete ceriman (era wax) sticky material
contain protective substances including
enzyme lysozymes and immunoglobulin's
•
8. Tympanic membrane (Ear drum )
Separates Auditory canal from middle ear
Formed by three types of tissue
• Outer covering ( hairless skin )
• Middle ear (fibrous tissue)
• Inner ear (lining of mucous membrane)
9. Middle Ear ( Tympanic cavity )
Irregular shaped air filled
cavity
Lined with simple squamous
or cuboidal epithelium
Medial wall is a thin layer of
temporal bone in which
there are two openings
• Oval window (occluded by
parts of small bones stapes )
• Round window (occluded by
sheet of fibrous tissue)
10. • Middle ear, three small bones (ossicles) form a
chain and conduct sound vibrations from the
eardrum to the inner ear. Once in the fluid-
filled inner ear, sounds are converted into
nerve impulses and sent to the brain
11. Ear Drum/Tympanic membrane vibrate when
sounds waves strike it
These waves transmit to three Auditory
bones/Auditory ausicles
These bones form movable joints with each
other are ;
• Milieus
• Incas
• Stapes
Stapes transmit vibrations to fluid filled inner
ear at oval window
12.
13. Eustachian Tube
Extend from middle ear to nasophyrnx
Permit ear entry (air to leave or enter middle
ear cavity )
Air pressure in middle ear must be same as
external atmospheric pressure in oder to
vibrate ear drum properly
14. • Equalize pressure between middle ear and
nasophyrnx
• Protects middle ear from nasopharyngeal
secretion
• Ventilation and drainage of middle ear
• What is Eustachian tube dysfunction ?
15. Inner Ear / labyrinth
Contains organs of
hearing or balance
Has two parts
• Bony labyrinth
• Membranous labyrinth
16. Bony labyrinth
Cavity within temporal bone
Larger than and enclosed membranous
labyrinth
• Perilymph :between the bony and membranous
labyrinth is layer of watery fluid called
perilymph
• Endolymph : fluid within membranous laybrinth
called endolymph
17. Bony labyrinth consist of
Vestibule : contain two membranous sacs are
utricle and saccule within these membranes
are hair cells
Cochlea Resembles a snail shells
Semicircular canal :three tubes continue with
vestibule
20. Cochlea
Cochlea is divided into three fluid filled canal
Three canals wrapped around a bony axis, the modiolus.
These canals are:
• Scala tympani
• Scala vestibuli
• Scala media (or cochlear duct)
Medial canal is cochlear Duct contain receptors for hearing
• Organ of corti : sensory organ, contain supporting cells
cochlear hair cells contain auditory receptors
Impulses generated by these cells carried out by 8th cranial
nerve to cerebellum, mid brain and cerebrum
21. Semicircular canals
No auditory function
Maintaining head position
Posture and balance
Vestibule
Utricle is membranous sac and other
three membranous ducts opens at their
dilated end , form Ampullae
22.
23.
24.
25. Eye
• Contain receptors for vision and refracting
system
• Eyelids contain skeleton muscles
• Eyelashes along boarder of eye lids
• Eyelids are lined within thin membrane called
conjunctiva
26. • Eye ball is within and protected by orbit ,
• Formed by
• maxilla,
• zygomatic,
• Frontal
• sphenoid
• ethmoid bone
27. • Six extrinsic muscles of eye attached to bony
socket
• Four Rectus muscles move eyeball up and
down or side to side
• Two oblique muscles that rotate eye
• Cranial nerves that innervate these muscles
are occulomotor, Trochler and Abducens
30. Lacrimal gland
• Located at upper ,outer boarder of eyeball
• Small ducts take tears to anterior of eyeball
• Tears are mostly water contain lysozymes
• At medial corner of eyelids are two small
openings into superior and inferior lacrimal
canals these ducts take tears to lacrimal sac
which leads to nasolacrimal duct empty tears
to nasal cavity
31.
32. Structure of Eye
There are three
layers of tissues
• Sclera and cornea
• Middle layer consist
of choroid ciliray
body iris
• Inner layer nervous
tissue retina
33. Sclera and cornea
• Sclera or white of eye , is thickest layer made
up of fibrous connective tissues
• Most anterior portion is the cornea differs
from rest of sclera in that it is transparent and
has no capillaries
• Cornea is first part of aye that refract light rays
34. Choroid
• Deep chocolate brown in color
• Contain blood vessels and dark blue pigment
that prevent glare
• Absorb light rays
Most anterior portion of choroid is
Cillary body
iris
35. Cilairy body and iris
• Cillary body is a circular muscle that surrounds
the edge of lens
• It connected to lens by suspensory ligament
• Lens is transparent elastic protein and has no
capillaries behind pupil
• Contraction and relaxation of cillary muscles
control the shape of lens
• Cillary body supplied by 3rd cranial nerve
36. Iris
• Iris is colored part of eye
Divides anterior segment of eye into anterior
and posterior chamber contain aqueous fluid
secreted by cillary body composed of pigment
cells
37. Retina
Innermost layer
Delicate structure
Composed of several layers of nerve cell bodies
and their axons
Light sensitive layer consist of sensory receptor
cells
• Rods ( leads to monochromic vision)
• Cones ( bright light and colors )
Which contain photosensitive pigments that
convert light rays into nerve impulses
38.
39. • Retina thins out anteriorly and thickest
posterioly ,near the center of posterior
portion is macula lutea or yellow spot
• In center of yellow spot is little depression
called fovea centralis consist of only cones
• Nerve fibers of retina converge to form optic
nerve
• Where optic nerve leave the eye is optic disc
or blind spot has no light sensitive cells
40. Anterior of eye ball
Two cavities within the eye
• Posterior cavity
• Anterior cavity
Posterior cavity : found between lens and retina and
contain vitreous humor this semisolid substance keep
retina in place composed of water, salts and
mucoprotein
• Maintain IOP ,
• IOP prevent walls of eyeball from collapsing
• IOP Maintain eye shape
• What is detached retina ?
41. • Anterior cavity found between the front of
lens and cornea contain aqueous humor
• this is the tissue fluid of eye ball and is formed
by capillaries in cilliary body flows through
pupil and is absorbed by scleral venous sinus
or canal of schlemm (small vein) at junction of
iris and cornea ,there is continuous production
and drainage
• Intraocular pressure?
42. Optic chiasma
• The optic chiasm is an
X-shaped structure
formed by the crossing
of the optic nerves in
the brain. The optic
nerve connects the
brain to the eye.
• This crossing over
provides both cerebral
hemispheres with
sensory input from
each eye
43. Optic tracts
• Optic track is actually comprised of
• Left optic tract transmit information from
tempororetinal fibers
• Right optic tract transmit information from
nasoretinal fibers
44. • Optic tract passed backwards to synapse with
nerve cells of lateral geniculate bodies of
hypothalamus
• From there nerve fibers proceeds backward
and medially as optic radiations
• Terminate in visual area of cerebral cortex
(in occipital lobe )
45. Physiology of Vision
Light rays must be focused on retina and resulting
nerve impulses must be transmitted to visual
areas of cerebral cortex in brain
• Refraction
Is the deflection or bending of a ray of light as is
passes through one object to another
Refraction of eye within the eye takes place in the
following pathway of structures are
Cornea to aqueous humor to vitreous humor
Lens is adjustable part of refraction system
46. • When looking at distant object ,cillary muscles
relaxed and the lens is elongated and thin
• When looking at near objects the cillary
muscles contract , the elastic lens recoil and
bulges in middle and has greater refractive
power
47. When light rays strike the retina ,stimulate chemical
reaction in the rods and cones .
In rods the chemical rhodopsin breaks down to form
scotopsin and retinene this chemical reaction generate
electrical impulses
Chemical reaction in cones brought about by three
types of cones
• Red absorbing
• Greem absorbing
• Blue absorbing
48. • Impulses from rods and cones transmitted to
ganglion neurons these converge at optic disc
and become optic nerve
49. Size of pupils
Control amount of light entering the eye
In bright light pupils constricted
In dim light pupils dilated
50. Accommodation
In Oder for near vision within about 6 meters
accommodation is required and following adjustments are
• Constriction of pupil : assist accommodation by reducing
width of beam of light entering the eye
• Convergence : movement of eye ball
Extrinsic muscles moves the eye to obtain clear image they
rotate eye
• Changing the Power of lens : changing in thickness of lens
Near vision
Distant vision
51. Types of Rhodopsins
• There are four types of rodhopsins
• Four types of photo pigments
• One in rod
• Three in cones
