Lectures of Anatomy by Dr. Noura El -Tahawy . Assist. prof. of Anatomy, Faculty of Medicine, Port Said University; Egypt 2018,

1. Anatomy of
The EAR
Dr. Noura El Tahawy
Assist. Professor Of Anatomy
Embryology& Molecular Cell Biology
Faculty of Medicine, Port Said
University, Egypt

2. 1. Describe the external ear. (auricle& ext. acoustic meatus,
tympanic membrane.)
2. Describe blood &nerve supply& lymphatic drainage of the
external ear.
3. Describe the middle ear. (walls, special features in the cavity of
middle ear, auditory ossicles& muscles)
4. Describe the course& branches of the facial nerve in the
middle ear.
5. Describe divisions and boundaries of mouth cavity.
objectives

3. Auricle

4. Auricle

5. Auricle

6. Auricle: is composed mainly of
cartilage, except for the lobule.
The auricle collects the sound
waves and directs vibrations into
the external auditory canal.
Has the following features:
1. Helix
■ The slightly curved rim of the
auricle.
2. Antihelix
■ A broader curved eminence
internal to the helix, which
divides the auricle into an outer
scaphoid fossa and the deeper
concha.
3. Concha
■ The deep cavity in front of the
antihelix.
4. Tragus
■ A small projection from the
anterior portion of the external
ear anterior to the concha
5. Lobule
■ A structure made up of areolar
tissue and fat but no cartilage.
The Auricle:

7. External acoustic meatus
• External Acoustic (Auditory)
Meatus
• ■ Is approximately 2.5 cm
long, extending from the
concha to the tympanic
membrane.
• ■ Its external one-third is
formed by cartilage, and the
internal two-thirds is formed
by bone. produces earwax.
• ■ Is innervated by the
trigeminal nerve and vagus
nerve, which is joined by a
branch of the facial nerve and
the glossopharyngeal nerve.

8. External acoustic meatus

9. External acoustic
meatus (bony
part)

10. External acoustic meatus

11. Tympanic membrane
(Ear drum)
■ Conducts sound waves to the middle ear.
■ Its external (lateral) concave surface is covered by skin and is innervated (sensory) by the
trigeminal nerve and the vagus nerve.

12. Eardrum
Tympanic membrane

13. Consists of three layers: an outer (cutaneous), an intermediate (fibrous), and an inner (mucous) layer. ■ Has a thickened
fibrocartilaginous ring at the greater part of its circumference, which is fixed in the tympanic sulcus at the inner end of the
meatus. ■ Has a small triangular portion between the anterior and posterior malleolar folds called the pars flaccida
(deficient ring and lack of fibrous layer). The remainder of the membrane is called the pars tensa. ■ Contains the cone of
light, which is a triangular reflection of light seen in the anterior–inferior quadrant. ■ Contains the most depressed canter
point of the concavity, called the umbo (Latin for “knob”).
Otoscope ‫االذن‬ ‫منظار‬Tympanic membrane

14. Middle Ear Walls and boundaries
Dr. Noura El Tahawy

15. Pterous temporal Bone
Cranial Cavity

16. erous temporal Bone

17. Temporal bone

18. Temporal bone

20. Tympanic cavity (Middle Ear Cavity)

21. Tympanic cavity

22. Eardrum
Tympanic membrane
The lateral wall of the Middle Ear

23. Medial wall of the Middle Ear
Promontory

24. Tegmen tympani
Roof of Middle ear

25. Floor of the Middle Ear
Bulb of Internal Jugular vein

27. Eustachian tube
(Pharyngo-tympanic tube)
Anterior wall of Middle Ear
nasoPharynx

28. NasoPharynx

30. Walls of the Middle ear

31. 1. Boundaries of the Tympanic Cavity ■ Roof: tegmen tympani (temporal bone).■ Floor:
jugular fossa. Anterior: carotid canal and Eustachian tube. ■ Posterior: mastoid air cells and
mastoid antrum through the aditus ad antrum. ■ Lateral: tympanic membrane. ■ Medial: lateral
wall of the inner ear, presenting the promontory formed by the basal turn of the cochlea, the
fenestra vestibuli (oval window), the fenestra cochlea (round window), and the prominence of
the facial canal.
2. Oval Window (Fenestra Vestibuli)
■ Is pushed back and forth by the footplate of the stapes and transmits the sonic vibrations
of the ossicles into the perilymph of the scala vestibuli in the inner ear.
3. Round Window (Fenestra Cochlea or Tympani)
■ Is closed by the secondary tympanic (mucous) membrane of the middle ear and
accommodates the pressure waves transmitted to the perilymph of the scala tympani.
Consists of the tympanic cavity with its ossicles and is located within the petrous portion of
the temporal bone.
■ Transmits the sound waves from air to auditory ossicles and then to the inner ear. A.
Tympanic (Middle Ear) Cavity
■ Includes the tympanic cavity proper (the space internal to the tympanic membrane) and the
epitympanic recess (the space superior to the tympanic membrane that contains the head of
the malleus and the body of the incus).
■ Communicates anteriorly with the nasopharynx via the auditory (eustachian) tube and
posteriorly with the mastoid air cells and the mastoid antrum through the aditus ad antrum.
■ Is traversed by the chorda tympani and lesser petrosal nerve.
Tympanic cavity (Middle Ear cavity)

32. Auditory (Pharyngotympanic or Eustachian) Tube
■ Connects the middle ear to the nasopharynx.
■ Allows air to enter or leave the middle ear cavity and thus balances the pressure
in the middle ear with atmospheric pressure, allowing free movement of the
tympanic membrane.
■ Has cartilaginous portion that remains closed except during swallowing or
yawning.
■ Is opened by the simultaneous contraction of the tensor veli palatini and
salpingopharyngeus muscles.

33. Contents of the Middle Ear
(tympanic cavity)

34. Ear Ossicles

36. Malleus

37. Malleus

38. Incus

39. Stapes

40. Transmission of Vioce

41. Muscles inside the Middle ear

42. Inner Ear

44. Vestibulocochlear nerve

45. Cochlear
part
Vestibular part
Facial nerve
Vestibulocochlear and Facial nerves

46. Facial Nerve

47. Facial nerve

49. Cochlear
part
Vestibular part
Facial nerve
Vestibulocochlear and Facial nerves

50. Facial nerve

57. Branches of Facial nerve

61. 1. The motor nucleus supplies the muscles of facial expression, the auricular muscles,
the stapedius, the posterior belly of the digastric, and the stylohyoid muscles
2. Parasympathetic (secretomotor) to submandibular and sublingual salivary glands
and the nasal and palatine glands.
3. Parasympathetic (secretomotor) supplies the lacrimal gland.
4. The sensory part receives taste fibbers from the anterior two-thirds of the tongue,
the floor of the mouth, and the palate.
Distribution
Facial nerve
Course:
1. The two roots (sensory and motor) of the facial nerve emerge between the pons and
the medulla oblongata. They pass laterally in the posterior cranial fossa with the
vestibulocochlear nerve (CVIII) and enter the internal acoustic meatus (internal
auditory canal) in the petrous part of the temporal bone.
2. At the bottom of the meatus, the nerve enters the facial bony canal and runs laterally
through the inner ear.
3. On reaching the medial wall of the middle ear (tympanic cavity) the nerve expands to
form the sensory geniculate ganglion and turns sharply backward at the roof of
middle ear (above the promontory).
4. Reaching the posterior wall of the tympanic cavity, the facial nerve turns downward,
descends to emerge from the stylomastoid foramen to exit the skull and enters the
parotid gland. Inside the parotid g. it terminates by dividing into five terminal
branches which supply muscles of facial expression.

63. Atlas of The Ear

67. Gross Anatomy of the Middle Ear

73. End