The document provides details on the anatomy and physiology of the human ear. It describes the structures of the outer, middle and inner ear including the auricle, tympanic membrane, ossicles, cochlea and vestibular system. It then explains the pathways for sound conduction and balance/spatial orientation from the inner ear to the brainstem and cortex.

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