1. Outer- and middle ear
Dr. Csáki Ágnes

2. Outer ear
- auricle
- external acoustic meatus
tympanic membrane (border)
Tubular canal
Roles:
-to transfer sound waves to the tympanic membrane, to make it oscillate
- help detecting direction

3. Middle ear
- tympanic membrane (border)
- tympanic cavity with the ossicles
- Eustachian tube
To transfer the oscillation of the tympanic membrane to the inner ear receptors in the labyrinth
Tube serves to equlalize the air pressure on the two sides of tympanic membrane

4. Inner ear
- bony labyrinth
- membranous labyrinth
Receptors for hearing and balance

5. incisura intertragica
Auricule
helix
tragus
anthelix
incisura intertragica
ETC.
antitragus
lobulus auricularis
Known inheritance, previously used to identify the father of children.

6. Elastic cartilage (cartilago auricularis)
Rudimentary muscles (mm. auriculares) (innervations: n. VII.)
Originally, the movements of the ear was useful determining the direction of the sound.
(see bats, cats)

7. Arteries, lymph vessels, nerves
n. V/3: auriculotemporal n.
Greater auricular n. (plex. cervicalis)
Arteries:
a. auricul. post. (a. carotis ext.)
Rr. aur. ant. (a. temp. superficialis)
Lymph vessels:
N.ly. paroidei spf.
Nn. ly. Retroauricularis
N.ly. paroidei prof.

8. Somatosensory innervations of outer ear
n. V/3: auriculotemporal n.
n. VII: (posterior auricular n.), auricular branches (clinical imp.!: Facialis paresis - VZV)
Greater auricular n. (plex. cervicalis)
Mechanical irritating may evoke coughing or nausea !
n. X: auricular branch,n. IX

9. External acoustic meatus
External auditory canal: S shaped, app. 3 cm, average diameter 0.6 cm
Cartilaginous and osseous parts, isthmus : foreign bodies!
Slightly curved, but could be straightened for the inspection of the tympanic membrane, pull backward and upward
Skin with cerumen glands, sebaceus glands, tragi
Cerumen: „earwax” screens out foreign bodies and keeps the epithelium from drying out
If cerumen absorb water it may obstruct the canal – partial loss of hearing
Relatively frequent inflammations, especially in small children
isthmus

10. External acustic meatus reaches its entire length by 9th years of age.
otoscope
External acustic
meatus
Eardrum
External acustic meatus reaches its entire length by 9th years of age.
Foreign objects!

11. the external acustic meatus.
position of eardrum
(FRONTAL SECTION)
External acustic
meatus
Middle
ear
cavity
External acustic
meatus
Right eardrum
Left eardrum
The eardrum makes an acute angle with the inferior and anterior walls of
external acustic meatus and an obtuse angle with superior and posterior walls of
the external acustic meatus.

12. External surface of the eardrum
OTOSCOPIC PICTURE
IV.
Stria mallearis I.
Posterior
side
umbo
III.
Anterior
side
II.
Taut portion - Pars tensa drawn inward, fibrocartilage ring
Lax portion - Pars flaccida (Schrappnell-membrane)
Str, keratinized epith. four quadrant:clinically impotrant for location of
Lamina propria lesion
Mucosa
Innervation: N. V, VII, IX, X

13. Tympanic membrane Cone shaped structure, its surface is 0.7 cm2.
Pars tensa
Pars flaccida
Umbo membr. tymp.
Stria mallearis
Prominentia mallearis
Plica mallearis post. (chorda tymp.)
Plica mallearis ant.
cone of light
Cone shaped structure, its surface is 0.7 cm2.
Its colour is pearl gray.
The colour and position of the membrane indicate the change of air pressure in the tympanic cavity or the presence of inflammatory disease.
(The location of cone of light is helpful in evaluating the tension of the membrane.)

14. Otitis media

15. perforation

16. Otitis media Preauricular abscess Encephalitis Labyrinthitis
Meningitis
Petrositis
Facial paresis
Mastoiditis
Peritonsillar abscess
Sinus-Phlebitis
(Sinus-Trombosis)

17. Tympanic cavity
Air filled cavity, communicating with the pharynx via the Eustachian tube (to equalize the pressures), and mastoid cells
Brick shaped having six walls
It is located in the pyramid
Antero-posterior diameter is longer than the medio-lateral one and runs parallel with the long axis of the pyramid
Medial and the lateral walls bulge into the cavity, it is similar to biconcave lens
Contains the chain of ossicles

18. Middle ear – ossicles Incus (anvil) malleus (hammer)
Role: to reinforce the oscillations of the tympanic membrane to be able to transfer oscillation to the perilymph of the inner ear – impedance matching
Stapes(stirrup)

19. Malleus Articular surface Head (caput) Lat. process. Ant. process
Manubrium

20. Incus Body (corpus) Articular surface Long leg (crus) downwards
Short leg (crus)
backwards

21. Stapes Head (caput) Crus ant. Crus post.
The base of stapes is fitted to the oval window.
Base

22. Auditory ossicles Malleus („hammer”) Incus („anvil”)
Caput (1)
Collum (3)
Manubrium (5)
Proc. lat. (4)
Proc. ant. (2)
Incus („anvil”)
Corpus (1)
Facies articularis (2)
Crus breve (3)
Crus longum (4)
Proc. lenticularis (5)
Stapes („stirrup”)
Caput (2)
Crus ant. (3)
Crus post. (4)
Basis (5)

23. Auditory ossicles Incudo-malleolar joint Incudo-stapedial joint
malleus 4
incus 6.
stapes 7. 5.
Short limb of incus
Head of malleus
Neck of malleus
Ant. ligament of malleus
Handle (manubrium) of malleus
Ant. limb of stapes
Post. limb of stapes
Lenticular process of incus
Head of stapes
Footplate (base) of stapes
eardrum

24. Suspension of auditory ossicles
In the tympanic cavity
Prussak space
Anular ligament
of stapes

25. Motion picture showing the movement of auditory ossicles
Function of auditory ossicle
The auditory ossicles function as a lever because they are joined
to each other (incudomallear and incudostapedial joints).
The axis, around which the lever moves, connects the fossa incudis
and the petrotympanic fissure.
When the soundwaves vibrate the tympanic membrane,
the auditory ossicles transmit its inward movement to the oval window
where the footplate of stapes is pushed inward and it generates
vibration of perilymph.
The base (footplate) of stapes is considerably smaller than
surface of the tympanic membrane. As a result, the vibratory force
of stapes is about 20 times greater than that of the tympanic membrane.
The ossicles increase the force but decrease the amplitude of
the vibration transmitted from the tympanic membrane to the oval window.

26. The tympanic membrane oscillates with greater amplitude than the stapes, but due to the differences in surface area the pressure exerted by stapes is much higher (also act as a two armed lever)
The sound waves must be amplified : impedance matching

27. Ossicles in situ Lig. incudis sup. Lig. mallei sup. Lig. incudis post.
Lig. mallei lat.
Ossicles in situ 1
Lig. mallei ant.
Chorda tympani
m. tensor tymp.
n. V/3.
m. stapedius
n. VII.

28. Ossicles in situ Cholesteatoma
The structures are covered with mucosa that it raised up into folds
Lig. mallei sup.
Plica mallearis ant. (Proc. ant. mallei)
Plica mallearis post. (Chorda tympani)
Lig. mallei ant.
Lig. incudis sup.
post.
Superior tympanic recess
(Prussak-space)
(between the collum mallei, pars flaccida and sup. and lat. Malleolar lig.
Crus longum
incudis
Cholesteatoma
M. tensor tympani
Manubrium mallei
M. stapedius
Membrana stapedialis
Basis stapedis
Lig. anulare stapedis
(Otosclerosis)

29. Ossicles in situ Sup. malleolar lig. m. tensor tympani
Lat. malleolar lig.

30. 3 emelet:
Epitympanum (epitympanic recess or atticus) – above the tympanic m.
Communicates with the mastoid air cells
Mesotympanum – medial to the tympanic m. (promontorium,umbo narrowest part)
Hypotympanum – below the tympanic m. - Communicates with the tuba auditiva

31. Epitympanum
Incus
Caput mallei
Chorda tympani
Surgery!
Tuba auditiva

32. Middle ear - Cavum tympani
Walls:
anterior:paries caroticus
posterior: paries mastoideus
lateral: paries membranaceus
medial: paries labyrinthicus
superior: paries tegmentalis
inferior: paries jugularis

33. Lateral wall (paries membranaceus)
Manubrium mallei
Epitympanic recess
Anulus fibrocartilagineus
chorda tympani
Tympanic membrane

34. Medial wall (paries labirinthicus)
Prominence of the lateral semicircular canal
fenestra vestibuli
(oval window, base of stapes)
Prominence of the facial canal
Semicanalis m. Tensoris tympani
Inlet of mastoid antrum
Opening of the auditory tube
Tympanic sinus
Promontory
Basal turn of cochlea
Sulcus promontory n. tympanicus (IX)
fenestra cochleae (round window, secunder tympanic membrane)

35. Superior wall (paries tegmentalis)
Tegmen tympani
(facial canal)
n. Petrosus major et minor
At the tegmen tympani the osseous wall of the cavity is extremely thin, easily broken in vivo and on the skulls.

36. Anterior wall (paries caroticus)
Opening of uditory tube
m. Tensor tympani
Carotid canal
(aa. Caroticotympanici)
As a developmental defect the internal carotid a. could be inside the cavity

37. Anterior wall of the tympanic cavity
Musclus tensor tympani
Tuba auditiva
Canaliculi caroticotympanici

38. Pharyngotympanic tube (tuba auditiva)
one third of the tube is bony two thirds are cartilaginous
protrution of the cartilage is the torus tubarius
at the torus is the tubal tonsill, lymphatic aggregation
lined with ciliated epithelium, cilia beat toward the epipharynx.
muscles arising from its membranous part:
m. salpingopharyngeus,
m. levator and
m. tensor veli palatini

39. Auditory tube – Eustachian-tube
Ostium pharyngeum tubae auditivae
Ostium tympanicum
Pars ossea (Canalis musculotubarius)
Pars cartilaginea – Pars membranacea
M. tensor veli palatini
M. levator veli palatini
Bacteria may migrate up the tube and incite a purulent middle ear infection

40. Auditory tube
Main role: to equalize the pressure on both sides of the tympanic membrane. The equalization is essential for maintaining normal tympanic membrane mobility which in turn necessary for normal hearing
When we swallow the levator and the tensor veli palatini contract, thus opening the pharyngeal side of the tube.
Opening is easier if the pressure in the tympanic cavity is higher!

41. Inferior wall (paries jugularis)
Foramen of tympanic canaliculus( n. tympanic) (fossula petrosa)

42. Posterior wall (paries mastoideus)
Antrum mastoideum
(Cellulae mast.)
Fossa incudis
Eminentia pyramidalis
(m. stapedius)
Canaliculus chordae tympani
(canalis facialis)
Any infection penetrating the mastoid cells is difficult to handle without surgical interference.

43. Mastoiditis acuta

44. Posterior wall (paries mastoideus)
Facial canal

45. Great petrosal nerve
Chorda tympani

46. Anterior view of tympanic cavity
Anterior wall is removed

47. Content of the tympanic cavity
Auditory ossicles suspended by ligaments
Nerves (branches of VII., IX., X. cranial nerves, sympathetic fibers)
Muscles: tensor tympani muscle (V/3)
stapedius muscle (VII)

48. Muscles of the tympanic cavity
Tensor tympani muscle
is about 2 cm long (innervated by V.). Its tendon turn laterally around the cochleariform process and attached to the manubrium of malleus. It tenses the tympanic membrane and reduces the amplitude of oscillation, pre-tenses the membrane, thus making it more sensitive.
Stapedius muscle
is smaller than the tensor (innervated by VII). Its tendon runs forward from the pyramidal minence and it is attached to the neck of stapes. It pulls stapes posteriorly and takes the posterior part of its base out off the oval window and reduces the extensive movement of stapes and in this way reduces the oscillatory range.
Acusticus reflex
hyperacusis
Both muscles are protective and none of them has antagonist.
Reflexes for the contractions of both muscles: need time to activate – does not protect against a sudden noise! (gunshot)
Mostly limit the transfer of deeper voices – increase signal/noise ratio!

49. n. auricularis post. n. VII.
Nerves
n. stapedius
n. tympanicus
r. auricularis n. X.
n. petrosus major
VII IX
n. auricularis post. n. VII. X
n. petrosus minor
n. VII.
plexus carotideus
chorda tympani

50. Peripheral facial paresis (Bell’s paresis)

51. Arteries A. tympanica anterior (a. maxillaris)
A. tympanica posterior (a. auricularis posterior→a. stylomastoidea)
A. tympanica superior (a. meningea media)
A. tympanica inferior (a. pharyngea ascendens)
aa. caroticotympanicae (a. carotis interna)
V. tympanica anterior (plexus pterygoideusba)
V. tympanica posterior (v. stylomastoidea → v.retromandibularisba)
V. tympanica superior (v. meningea media → sinus sphenoparietalisba)
V. tympanica inferior (plexus pharyngeusba)
Arteries

52. Conductional deafness
otosclerosis
perforation of the tympanic membrane caused by chronic otitis media or trauma
Diseases of external and middle ears may cause conduction deafness
Otosclerosis is a progressive conduction deafness in adults caused by bone formation around the stapes and oval window. The footplate is fixed and it can not transmit
the sound vibration to the perilymph.
Inflammation (otitis media) is especially frequent in infants

53. Development of the external ear
Auricle:
3 mesenchymal proliferation of 1st pharyngeal arch
3 mesenchymal proliferation of 2nd pharyngeal arch

54. Development of the middle ear
Pharyngeal arches
outer pharyngeal grooves: ectoderm
inner pharyngeal pouches: endoderm
Tympanic cavity:
lateral part of 1st pharyngeal pouch
Auditory tube
medial part of 1st pharyngeal pouch
Tympanic membrane:
ectodermal epithelium of 1st pharyngeal groove
endodermal epithelium of 1st pharyngeal pouch
intermediate mesenchyme (connective tissue)
External acoustic meatus:
from epithelium of 1st pharyngeal groove

55. Development of the middle ear
Ossicles:
malleus (anterior lig. of malleus) and incus:
from 1st pharyngeal arch cartilage
stapes:
from 2nd pharyngeal arch cartilage
ossicles remain embedded in mesenchyme until the 8th month
Muscles:
tensor tympani:
from 1st pharyngeal arch
stapedius:
from 2nd pharyngeal arch

56. Irodalom
Szentagothai J, Réthelyi M: Funkcionális anatómia, Medicina, 1989
Sobota - Atlas of Human Anatomy, 20th edition, Urban and Schwarzenberger, 1993
Guyton, Arthur C - Textbook of medical physiology, 11th edition, Elsevier Inc., 2006
Klinikai felvételek:
A radiológiai felvételek a következő oldalról származnak:
A fénymikroszkópos felvételek a Humánmorfológiai Intézet metszeteiről készültek.

57. Vestibulum, sacculus can. Semicirc. Internal acoustic meatus
Facial canal
Vestibulum, sacculus can. Semicirc.
Internal acoustic meatus
Cochlea, n. cochlearis nodiolus
Antrum mastoideum
Stapes, in oval window
Malleus, head
promontory
External acoustic meatus
Middle ear
m. Tensor tympani, tendo
Tympanic membrane