The document summarizes the anatomy and function of the ear. It describes the three main divisions of the ear - the outer, middle and inner ear. The outer ear collects sound waves. The middle ear contains the ossicles that transmit vibrations from the eardrum to the inner ear. The inner ear converts vibrations to neural signals via hair cells in the cochlea and balances functions in the semicircular canals. The ear detects sound and maintains equilibrium through these specialized structures that work together to transmit physical vibrations to the brain for processing.

1. Functional Anatomy of the
Ear
Mutyaba Ibrahim
Nakasi Juliet
Katongole Richard
Natukunda Sharon
Ndato isreal
Alowo catherine

2. Mutyaba Ibrahim;2016-DCM-FT-FEB-001
Alowo Catherine;2015-DCM-FT-002
Nakasi Juliet;2015-DCM-FT-009
Katongole Richard;2015-DCM-FT-023
Muhindo Israel;2015-DCM-FT-004

3. Major Divisions of the Ear
Peripheral Mechanism Central Mechanism
Outer
Ear
Middle
Ear
Inner
Ear
VIII
Cranial
Nerve
Brain

4. External ear, Auris externa
Auricle
external auditory canal
eardrum(tympanic mebrane)
Middle ear, Auris media
Auditory ossicles
auditory(eustachian)tube
Inner ear, Auris interna
cochlea
Semicircular ducts
Utricle
saccule

6. Outer Ear
Pinna
External
Auditory
Meatus
Pinna
Preauricular Tags
Preauricular Pits
EAM
Cerumen
Function
EAM resonance
 Collects sound
 Localization
 Resonator
 Protection
 Sensitive (earlobe)

7. Pinna(auricle)
 The visible portion that is
commonly referred to as "the ear"
 Helps localize sound sources
 Directs sound into the ear
 Each individual's pinna creates a
distinctive imprint on the acoustic
wave traveling into the auditory
canal

8. • Its a flap of cartilage shaped like flared end of a trumpetand
covered by the skin.
• The rim of the auricle is called th helix,the inferior portion is
called lobule.the auricle is attached to the head by
ligaments and muscles
• Lymphatics;drain into parotid group,upper deep
cervical and mastoid lymphnodes
• Veins;dain into into external jugular,common facial
vein
• Arteries;posterior auricular branch of external
carotid artery,ant.auricular branch of superficial
temporal and a branch of occipital artery

9. External Auditory Meatus
 Is a curved tube about 2.5cm that lies in the temporal boneand leads
from the auricle to the eardrum
 Near to the exterior opening of the external auditory
canal contains a few hairs and specialized
sebaceous(oil)glands called ceruminous glandsthat
secrete cerumen(earwax)
 The combination of hairs and cerumen help prevent dust
and foreign objects from entering the ear.
 Some people often produce abnormal amount of
cerumen and it becomes impacted and muffles incoming
sounds and its treatments is periodic irrigation

10. eardrum
Also called tympanic membrane
It is a thin,semitransparent partiton between the
external auditory canal and middle ear.
The eardrum is covered by the epidermis and lined
by simple cuboidal epithelium.
Between the epithelial layers is connective tissue
composed of collagen and elastic fibers and
fibroblasts.

11.  Middle Ear
-auditory ossicles
(transmit and mplify sound from
the tympanic membrane to the
oval window)
-auditory(eustachian)tube
(equalizes pressure on both
sides of the tympanic membrane

12. Function of Middle Ear
 Conduction
– Conduct sound from the outer ear to the inner ear
 Protection
– Creates a barrier that protects the middle and inner areas
from foreign objects
– Middle ear muscles may provide protection from loud
sounds
 Transducer
– Converts acoustic energy to mechanical energy
– Converts mechanical energy to hydraulic energy
 Amplifier
– Transformer action of the middle ear
– only about 1/1000 of the acoustic energy in air would be
transmitted to the inner-ear fluids (about 30 dB hearing loss)

13. The middle ear is a small,airfilled cavity in the temporal bone that is
lined by epithelium.it is separeted from the internal ear by a thin
bony partition that contains two small membrane-covered
openings;the ovalwindow and round window
The posterior wall of the middle ear communicates with the
mastoid air “cells”of the temporal bone through the tympanic
antrum and this explains why a middle ear infection may spread to
the temporal bone causing mastoiditis or even to the brain
The ant.wall contains an opening that leads directly into the
eustachian tube.

14. Auditory tube
• It consists of both of both bone and hyaline
cartilage and connects the middle ear with the
nasopharynx.it is normally closed at its
medial(pharyngeal)end;during swallowing and
yawning,it opens,then atmospheric pressure from
throat enters or leaves the middle ear until
int.pressure is =to external pressure.
• When the pressures are balanced,the eardrum
vibrates freely as soundwaves strike it
• It is also a route where pathogens can travel from
throat and nose to the middle ear

15. Ossicles
 Malleus
(hammer)
 Incus
(anvil)
 Stapes
(stirrup)
smallest bone
of the body

16. Ossicles
named for their shapes.they are commonly called
hammer,anvil,stirrup
-they are connected by synovial joints,
the handle of malleus is attached to the int.surface
of the eardrum,the head articulates with the body
of incus,incus then articulates with the head of
stapes
-the base of stapes fits into the oval
window(membrane covered opening
-directly bellow it is the round window which is
enclosed by a membrane called secondary tympanic
membrane

17. Ossicle ct’d
• Allows communication btn the external and
internal ear and amplification
• Ligaments;lateral ligament of malleus,ant.ligament
of malleus,sup.ligament of malleus,post.ligament of
incus
• Muscles;tensor tympani,stapeius
• Round window(fenestra cochlea)has a opposite
vibration phase to that entering the inner ear via
the oval window,allows fluid in the cochlea to move
and transfer sound waves
• Facial nerve and chorda tympani nerve

18. Inner Ear

19. Inner ear
 It is also called the labyrinth because
of its complicated series of canals
 Two main structural divisions;an
outer bony labyrith and an inner
membranous labyrinth
 The bony labyrinth is a series of
cavities in the petrous portion of the
temporal bone.
 It can be divided into 3 parts
namely;the semicircular
canals,vestibule both of which
contain receptors for equilibrium and
the cochlea which contains receptors
for hearing

21.  The bony labyrinth is lined with periosteum and
contains a fluid called perilymph which is chemically
similar to csf,it sorrounds the membranous
labyrinth,a series of sacs and tubes inside the bony
labyrinth and having the same general form
-the membranous labyrinth is lined with epithelium
and contains a fluid called endolymph,which is
chemically similar to intracellular fluid

22. • The vestibule is the oval central
portion of the bony labyrinth.the
membranous labyrinth in the vestibule
consists of two sacs called the utricle and
saccule which are connected to each other
by a duct
•Projecting superiorly and posteriory are the
semicircular canals.
•Each lies at approx.right angles to the other
two and based on their positions they are
called anterior,posterior,and lateral canals

23. Semicircular canals
 The anterior and post.semicircular canals are
oriented vertically;the lateral one is oriented
horizontally.
 One end of each canal is a swollen
enlargement called the ampulla.
 The portions of the membranous labyrinth that
lie inside the the bony semicircular canals are
called circular ducts(membranous semicircular
canals),these communicate with the utricle of
the vestibule

24.  Ant.to the vestibule is cochlea,it is a bony spiral canal
resembling a snail's shell and makes almost three turns
around the central bone core called modiolus
 Sections through it show that it is divided into 3
channels,together the partitions that separate the channels
have a shape like letter Y
 The channel above the bony partition is the scala vestibuli
which ends at the oval window,the channel bellow is the
scala tympani which ends at the round window;they both
contain perilymph and are completely separate except for an
opening at the apex of the cochlea:helicotrema
cochlea

26.  The cochlea adjoins the wall of the vestibule,into
which the scala vestibuli opens.
 The perilymph of the vestibule is continous with
that of the scala vestibuli
 The 3rd duct is the cochlear duct separated from the
scala vestibuli by the vestibular membrane
 The basilar membrane separates the cochlear duct
from the scala tympani.
 Resting on the basilar membrane is the organ of
corti(the organ of hearing) or spiral organ which is
coiled sheet of epithelial cells including supporting
cells and abt 16000 hair cells which are the
receptors for auditory sensations

27. Hair cells
 There are two groups of hair cells;the inner hair cells
are arranged in a single row and extend the entire
length of the cochlea,the outer hair cells are
arranged in several rows
 The cells have hairlike microvilli at their apical ends
that extend into the endolymph of the cochlear duct
 The basal ends synapse with the 1st order neurons
and motor neurons from the cochlear branch of the
vestibulocochlear nerve(VIII)

28. Function of Inner Ear
 Converts mechanical
sound waves to neural
impulses that can be
recognized by the brain
for:
– Hearing
– Balance

29. Organ of Corti

30. Sensory cells of
the organ of Corti

31. refferences
• MEDICAL PHYSIOLOGY by Guyton and Hall 11th
edition
• PRINCIPALS OF ANATOMY AND PHYSIOLOGY by
Totora
• https://en.wikivet.net/ear_-
_Anatomy_%26_physiology
• https://google.com/search?q=function+of+the+rou
nd+window
• Pocket anatomy and physiology by Shirley A.jones