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