The ear has three main sections - the outer, middle, and inner ear. The outer ear collects and directs sound waves through the external auditory meatus to the eardrum. The middle ear contains the auditory ossicles that transmit vibrations through to the inner ear. The inner ear senses both hearing and equilibrium, containing the cochlea which detects sounds and the vestibular system that monitors movement and orientation. Receptors in the cochlea and vestibular system of the inner ear enable the senses of hearing and balance.

1. The Anatomy of the Ear

2. • provides the senses of equilibrium and
hearing
equilibrium- informs us of the position of the
body in space by monitoring gravity, linear
acceleration, and rotation.
hearing- enables us to detect and interpret
soundwaves.

3. 3 Anatomical Regions of the Ear
1. External Ear
2. Middle Ear
3. Inner Ear

4. The External Ear

5. - visible portion of the ear
- collects and directs
soundwaves to the
eardrum
Composed of:
1. the auricle, or pinna, and
2. the external acoustic
meatus.

6. The Pinna
- surrounds the entrance to
the external auditory canal
- supported by elastic
cartilage
- protects the opening of
the canal
- collects and convey
soundwaves to the
tympanic membrane

7. The Pinna
Features:
1. Concha
2. Helix
3. Crus of Helix
4. Lobule
5. Antihelix
6. Scapha
7. Tragus
8. Antitragus
9. Intertragic notch

8. The External Auditory Meatus
- Extends from the concha to
the tympanic membrane.
- Its length, from the floor of
the concha, is
approximately 2.5 cm and
from the tragus about 4
cm.
- It has two structurally
different parts, the lateral
third being cartilaginous
and the medial two-thirds
osseous.

9. The External Auditory Meatus
• Features:
1. skin
2. Hair
3. Sweat Glands
4. Sebaceous Glands
/Ceruminous Glands
-slows down the growth
of bacteria and reduces
the chances of infection

10. Tympanic Membrane
- separates the external
and middle ear
- transmits soundwaves
along the auditory
ossicles to the inner ear.
- the deepest part of which
is the umbo where the
tip of the handle of the
malleus is attached.

11. The Middle Ear

12. Middle Ear
- also known as the
tympanic cavity
- space in the petrous
temporal bone lined by
mucous membrane
The cavity has two parts:
1. the tympanic cavity
proper, opposite the
membrane, and
2. an epitympanic recess,
contains the malleus and
incus.

13. Walls of the Middle Ear
Anterior - opens directly to
the eustachain tube
Posterior - presents a large
opening - aditus - that
leads to the tympanic
antrum, where the
stapedius m. is found.
Lateral - tympanic membrane
Medial - foramen ovale of
the vestibule
Roof - tegmen tympani

14. Middle Ear
Muscles:
1. Tensor Tympani M.
2. Stapedius M.
Bones:
1. Malleus (hammer)
2. Incus (anvil)
3. Stapes (stirrup)

15. The Inner Ear

16. The Inner Ear
- located in the
petrous part of the
temporal bone
- the senses of
equilibrium and
hearing are
provided by the
receptors of the
inner ear, which
lies in the
membranous
labyrinth.

17. The Inner Ear
Two Labyrinths:
1. Bony labyrinth
2. Membranous
labyrinth

18. The Bony Labyrinth

19. The Bony Labyrinth
1. Bony Labyrinth - about 3 mm.
thick that is as hard as ivory.
3 parts:
a. Vestibule
b. Semicircular Canals
c. Cochlea

20. The Vestibule of the Bony Labyrinth
- the central part of
the bony labyrinth
behind the cochlea
containing the
fenestra vestibuli
enclosed by the
stapes.
- contains the utricle
and saccule which
contain receptors for
the sensation of
gravity and linear
accelaration.

21. The Semicircular Canals
- 3 horseshoe-
shaped fluid-
filled canals
that contain
receptors
stimulated by
the rotation of
the head.

22. The Cochlea
- the bony cochlea
contains the
cochlear duct of
the membranous
labyrinth.
- contains receptors
in the cochlear
ducts that provide
the sense of
hearing.

23. The Membranous Labyrinth

24. Membranous labyrinth
- lies within the bony labyrinth and consisting of sacs
that contain fluid known as endolymph.
- The fluid that separates the bony and membranous
labyrinth is known as perilymph.
This is made up of:
a. Scala Tympani
b. Scala Vestibuli
c. Cochlear duct - organ of corti

25. Membranous labyrinth

26. The Cochlea