1. Prepared & presented by:
Anatomy of the Ear
Prepared & presented by:
Prof. Dr. Hassan M. Serry
© Anatomy and Embryology department, ASU, Month/Year 12/2012

2. By the end of this lecture, you should be able to:
ILOs
By the end of this lecture, you should be able to:
List parts of the ear.
Describe parts of External ear: auricle & external auditory meatus and give their nerve supply and its applied anatomy.
Describe roof, floor, and walls of Middle ear and enumerate its contents.
Identify parts and function of auditory tube.
Name parts of Internal ear: bony & membranous labyrinth.

3. The Ear

4. It is the organ of Hearing and also concerned with Equilibrium

7. External
Ear

10. AURICLE

16. EXTERNAL ACOUSTIC (AUDITORY) MEATUS

18. 1/3
2/3
24 mm in length

20. It describes an S-shaped curve
Lateral
Medial

21. TYMPANIC MEMBRANE (EAR DRUM)

22. about 10 mm in diameter
it is obliquely directed making an angle of 55 with the floor of the meatus

23. posterior
anterior

29. Middle
Ear

31. Epitympanic recess
Tympanic cavity proper

32. Posterior
Anterior

33. Anterior (carotid)
wall

34. Canal for
Tensor tympani
Bony part of
Auditory tube
Internal carotid artery

36. Posterior(mastoid)
wall

37. Aditus to
Mastoid antrum
Pyramid

39. Roof (tegmental)
wall

40. Tegmen tympani

41. Floor (Jugular)
wall

42. Tympanic branch of XI
Internal jugular vein

43. Medial (Labyrinthine)
wall

46. Promontory
Prominence of
Facial n. canal
Fenestra vestibuli
Fenestra chocleae
Sinus tympani
Tympanic plexus of ns.

48. Lateral (membranous)
wall

50. CONTENTS OF TYMPANIC CAVITY

52. Auditory Ossicles

53. Malleus
Lateral
Incus
Anterior
Stapes
Posterior
Medial

56. Muscles of
tympanic cavity

58. Action
The tensor tympani and stapedius usually contract together in reflex response to sounds of fairly high intensity, exerting a 'protective damping effect before vibrations reach the internal ear
The tensor pulls the tympanic membrane inwards to tense it and also pushes the stapes more tightly into the fenestra vestibuli. The stapedius muscle opposes the tensor in the latter action.

59. Pharyngotympanic
(Auditory)
tube

60. Tympanic
caviry
Pharyngotympanic tube
1/3
2/3
Pharynx
36 mm in length

61. The internal ear (Labyrinth)

62. The labyrinth is situated in the petrous part of the temporal bone, medial to the middle ear.
It consists of the bony labyrinth, comprising a series of cavities within the bone.
and the membranous labyrinth, comprising a series of membranous sacs and ducts contained within the bony labyrinth.
Labyrinth

64. Bony Labyrinth
Labyrinth

65. Cochlea
Vestibule
Semicircular canals

66. Vestibule
Labyrinth

67. Right bony labyrinth Anterolateral view
Semicircular
canals
Vestibule
Posterior
Anterior
Oval window
(Fenestra vestibuli)
Scala vestibuli

68. Right bony labyrinth Top view
Semicircular
canals
Aqueduct of vestibule
Vestibule
Lateral
Medial
Oval window
(Fenestra vestibuli)
Scala vestibuli

69. Semicircular canals
Labyrinth

70. Right bony labyrinth Anterolateral view
Anterior semicircular
canal
Lateral semicircular
canal
Ampullae of semicircular
canals
Posterior
Anterior.
Posterior semicircular
canal

71. Semicircular canals
Anterior
Lateral
Posterior

72. Cochlea
Labyrinth

73. Cochlea (snail shell -shaped)القوقعة
It opens into the anterior part of the vestibule
it consists of a central pillar, the modiolus, around which a hollow bony tube makes two and one half spiral turns
Each successive turn is of decreasing radius so that the whole structure is conical. The apex faces anterolaterally and the base faces posteromedially
The first basal turn of the cochlea is responsible for the promontory seen on the medial wall of the middle ear.
Labyrinth

74. Right bony labyrinth Anterolateral view
Cochlea
Apex
Basal turn
Posterior
Anterior.

75. Section
of cochlea
Cochlea
Modiolus
Basal turn

76. Internal auditory meatus
Section
of cochlea
Cochlea tube
Scala vestibuli
Spiral lamina
Scala tympani
Modiolus
Internal auditory meatus

77. Longitudinal section of cochlea
Cochlea tube
Scala vestibuli
Modiolus
Scala tympani
Spiral lamina
Spiral ganglion

78. Section of cochlea Basilar membrane Vestibular membrane
Scala vestibuli
Modiolus
Scala tympani
Spiral ganglion
Spiral lamina

79. Membranous Labyrinth
it is contained within the bony labyrinth but much smaller in size.
It is filled with endolymph
Its walls receive the branches of the vestibulocochlear nerve.
Labyrinth

80. Anterior semicircular duct Ampulla
Lateral semicircular
duct
Anterior semicircular duct
Ampulla
Endolymphatic duct
and sack
Dura mater
Posterior semicirular
duct
Cochlear duct
Utricle
Utricosaccular duct
Saccule
Scala vestibuli
Cochlear canaliculus
Scala tympani
Labyrinth

81. Labyrinth

82. Thank
You