Ear

1. By- Dr. Armaan SinghBy- Dr. Armaan Singh
Detail Anatomy of Ear

2.  Auricle
 One third
cartilaginous
 Two thirds bony
 Medial tympanic
membrane

4.  Roof shorter than floor
 Lined with columnar
epithelium
 Ceruminous glands
 Otis externa
(swimmer’s ear)
 Pain on pulling lobule

5.  Three layers
 Outer squamous
 Middle fibrous
 Deficient superiorly
 Flaccid in upper portion
 Handle of malleolus
embedded in fibrous
layer
 Inner mucous membrane
 Concave laterally
 Umbo

6.  Set at angle
55°horizontal
 Nerve supply
 Great auricular
 Post inferior quadrant
facial
 Tympanic branch of
glossopharyngeal
 Facial nerve
 Blood supply
 Superior more
vascular

7.  Biconcave
 Roof: tegmen
tympani
 Floor: bone
separates it from
carotid canal
 Tympanic branch
of
glossopharyngeal
nerve

8.  Lateral wall
 Tympanic membrane
 Epitympanic recess
 Medial wall
 Lateral semicircular
canal
 Canal facial nerve
 Promontory
 Tympanic plexus

9.  Canal tensor tympani
muscle
 Opening Eustachian
tube
 Anterior opening for
chorda tympani nerve
 Bone separates it from
carotid canal
 Caroticotympanic
nerves

10.  Opening mastoid
antrum
 Pyramid
 Opening for
stapedius muscle
 Canal for facial nerve
 Posterior opening of
chorda tympani

11.  Air
 Ossicles
 Tensor tympani
muscle
 Stapedius muscle
 Chorda tympani
 Facial nerve
 Caroticotympanic
nerves

12.  Malleous
 Head, neck,
handle, anterior
process, posterior
process
 Incus, body long
and short process

13.  Stapes
 Neck
 Anterior and
posterior
 Foot piece fits into
 Oval window
 Stapedius muscles
inserted back of neck
of stapes
 Facial nerve

14. Chorda Tympani

15.  Synovial joints
 Capsule consists
mainly of elastic
tissue
 Transmits sound
waves from air to
scala vestibuli
 Otosclerosis

16.  Two thirds
cartilaginous
 One third bony
 Medial forms tubal
elevation in lateral wall
nasopharynx
 Opens into anterior
wall of middle ear
 Levator and tensor
palati muscles open
Eustachian tube
 Equalise pressure on
tympanic membrane

17.  Cochlea
 Cochlear nerve
 Cochlear nuclei
 Central auditory
pathway
 Cortex temporal lobe

18.  2 ¾ turns
 Modiolus central
pillar
 Axis of internal
acoustic meatus
 Spiral lamina
 Basilar membrane
 Vestibular
membrane

19.  Oval window
 Scala vestibuli
 Scala tympani
 Secondary tympanic
membrane
 Contain perilymph
 Scala media or duct
of cochlea
endolymph

20.  Basilar membrane
 Spiral organ
 Hair cells of organ of
corti
 Tectorial membrane
 Single row of inner
hair cells
 Each one has 20
large afferent
 Outer hair cells

21.  Auricle
 External ear
 Tympanic membrane
 Malleous, incus, stapes
 Oval window
 Pressure waves in scala
vestibuli, scala media,
scala tympani
 Round window

22.  Travelling wave
theory
 Low tones peak at
apex
 High tones at base

23.  Receptors are hair
cells of organs of
corti
 Bipolar cells
 Cell bodies are in the
spiral ganglion on the
 Spiral lamina
 Auditory nerve
attached to lower
border of pons
 Cerebellar-pontine
angle

24.  First order neurones
end on ventral and
dorsal cochlear
nuclei
 On inferior
cerebellar peduncle
 2nd
order neurones
 Trapezoid body
 Lateral leminiscus
 Inferior colliculus
 Superior olivary
nucleus

25.  Inferior colliculus
 Via inferior brachium
 Medial geniculate
body
 3rd
order neurones
 Auditory radiations to
auditory cortex in
temporal lobe

26.  Fibres arise from
 Ventral cochlear nucleus
 Dorsal cochlear nucleus
 Form lateral leminscus
 Superior olivary nucleus
 Mainly contra lateral
 Fibres end in inferior
colliculi nuclei back of
midbrain

27.  Receives inputs from
both ears
 Intensity and timing
 Ipsilateral are excitatory
and earlier and more
intense
 Contralateral inhibitory
via nucleus in trapezoid
 Projects to inferior
colliculi

28.  Spatial information
 Superior olivary nucleus
 Intensity from ventral
cochlear nucleus
 Pitch from dorsal
cochlear nucleus
 Projects to medial
geniculate body
 Inhibitory to opposite
collicular nucleus

29.  Medial geniculate body
 Specific thalamic nucleus
for hearing
 Laminated and tone topic
 Fibres project as auditory
radiations to primary
auditory cortex
 Superior temporal gyrus
and adjoining part of
insula

31.  Temporal lobe
 Heschl gyrus
 Posterior portion
high tones
 Anterior low tones
 Bilateral
represented

32. Primary Auditory Cortex

33.  Auditory to motor
nucleus of 5th
and 7th
 Contraction of tensor
Tympani and
stapedius
 Dampen vibrations
 Auditory to reticular
nuclei arousal
 Connect to facial

34.  Conduction
 External
 Middle
 Inner ear
 Nerve deafness

35.  Visual system
 The conscious
proprioceptive system
 Vestibular system

36.  Bony labyrinth
 Bony cochlea
 Vestibule
 Bony semicircular
canals
 Contain perilymph
 Communicates with
CSF
 Subarachnoid space

37.  Membranous labyrinth
 Superior and posterior
common opening at non
ampullary end
 Lateral semicircular
canals
 Five openings into utricle
 Endolymphatic duct
 Saccule
 Ductus reuiens
 Duct of cochlea
 Contain endolymph

39.  Sensory static receptors
in macula of the utricle
and saccule
 Cristae of the ampullae
are the end organs of the
dynamic movement
semicircular canals
 Maculae respond to linear
acceleration of head in
horizontal or vertical
plane during walking

40.  Hair cells are found in
the macula discharge
all the time
 Cilia on the hair cells
embedded in gelatinous
substance containing
calcium carbonate
crystals

41.  Cell bodies are in the
vestibular ganglion in
the internal acoustic
meatus
 Relay in vestibular
nucleus

42.  Vestibular nucleus
to contra lateral
 Ventral posterior
nucleus of
thalamus
 Behind face area of
somato-sensory
cortex

43.  Lateral vestibulospinal
tract arises from lateral
or Deiter’s nucleus
 Descends in anterior
column of same side
 Synapse on anti-
gravity motor neurones
 Active during walking
 Antigravity in utricle
 Free fall saccule

44.  Medial vestibulo-spinal
 Descend bilaterally
 Medial longitudinal
Fasciculus (MLF) to
cervical cord
 Head righting reflex
 Eye righting reflex
 Arise from lateral
vestibular nucleus
 Extra ocular nuclei

45.  Afferents from the
cristae end in medial
and superior
vestibular nuclei
 Two way connection
with
 Flocculo nodular lobe
to all vestibular nuclei

46. Vestibular Pathway

47. Vestibular Pathway

48.  Rightward head turn
activates in the right
lateral semicircular
canal
 Resulting in
contraction of left
lateral rectus and right
medial rectus

49.  Under cerebellar
guidance
 Right medial
vestibular nucleus
 Responds to
rightward head turn
 Impulse to opposite
para median region
 Medial rectus

50.  Horizontal vestibulo-
ocular reflex
 Fast and slow phase
 Called after fast phase
 Nystagmus
accompanied by
vertigo

51. Cortical Eye Fields