ENT - Review of Anatomy

and Physiology of the Ear

and Nose and other
Important Face and Neck
Structures
Anatomy &
Physiology of the
EAR
OBJECTIVES

To identify the major

structures & functions of the
ear.
Embryology
 External ear – Ectoderm & Mesoderm
 Auditory Ossicles – mesenchymal origin
 Tympanic and Eustachian tube – first pharyngeal pouch
 Inner ear – ectodermal origin
Embryology
 Auricle
 develops from six
aural hillocks

 3 on first pharyngeal
arch

 3 on the second
pharyngeal arch
Embryology

Pharyngeal Hillock Auricle Component

Arch

Arch 1 1 Tragus
2 Helical crus
3 Helix
Arch 2 4 Antihelix
5 Antitragus
6 Lobule
Anatomy & Physiology of the
EAR
 External
 Auricle and External ear
canal
 Middle
 Tympanic membrane,
tympanic cavity, auditory
ossicles, intra-auricular
muscles and air cells of
temporal bone
 Inner
 Petrous bone (semicircular
canal system and cochlea)
External EAR
Auricle
-Composed of flexible
cartilage and of bone which
are attached to the skin by
their perichondrium and
periosteum.
External EAR

- Functions as a wind
break (air turbulence)
External EAR
External Auditory
Canal

Contains cerumen
glands that moisten /
soften skin

Itforms an S-shaped
curve

About 2.5cm in
length
External EAR

EAC (2 parts)
Lateral 1/3 (external) is skin-
lined cartilage with many
sebaceous glands and
ceruminous (wax producing)
glands and hairs.
Medial (inner) 2/3 is a more
sensitive skin lining a bony
canal (tympanic part of the
temporal bone)
Middle EAR
 Consist of air-filled cavity
 Communicates with the
nasopharynx via the
eustachian tube
 Separated from the EAC by
the TM
 Linkedto the inner ear via 3
ossicular chain
Middle EAR
 Tympanic Membane
 Thin membrane
 Vibrates in response to sound
waves
 Changes acoustical energy into
mechanical energy
Middle EAR

 Tympanic Membane
 Layers
 Outer epithelial layer,
which is continuous with
the skin lining the meatus
 Inner mucosal layer,
which is continuous with
the
mucosa of the middle ear
 Middle fibrous layer,
which encloses the
handle of
malleus and has three
types of fibres-the radial,
circular and the
parabolic
Middle EAR
Ossicles

Malleus (Hammer)
Incus (Anvil)
Stapes (stirrup)
The Ossicles
 Malleus (Hammer)
The Ossicles
 Incus (Anvil)
The Ossicles
 Stapes (stirrup)
Articulated Ossicular Chain
Ligaments of the Ossicular Chain

❑ Superior malleal
ligament
❑ Anterior malleal
ligament
❑ Lateral malleal
ligament
❑ Posterior incudal
ligament
Middle EAR

 Functions

 Impedance
Matching

 Protection
Middle EAR

 99.9% of the
energy would
be reflected at
the boundary
Middle EAR

 Acoustic Reflex (Stapedius

Reflex)
 Contraction of the tympanic
muscles are reflexive and in
response to rather loud sounds
coming into the ear.
 Reflex is bilateral
Middle EAR

 Eustachian Tube
 35-38 mm long
 Functions
 Ventilates the tympanic
cavity and air cells
 Equalizes pressure differences
between the tympanic cavity
and the atmosphere
Middle EAR

 Eustachian Tube
 Functions
 Drains the middle ear
spaces
 Creates a barrier to
ascending infection
Inner EAR

 Consistof multiple
interconnected
ducts (Labyrinth)

2 parts:
 Bony
 Membranous
Inner EAR

 Bony Labyrinth
 Separated from
membranous
labyrinth via space
filled with perilymph

 Encloses the
membranous
labyrinth
Inner EAR

 Membranous
Labyrinth
 Filled with K+ rich
fluid (endolymph)
 Sensory cells (Hair
cells)
 Divided in 2 parts
 Vestibular labyrinth
 Cochlea
Inner EAR

 Vestibular
Labyrinth
 3 semi circular canal
 Utricle
 Saccule

 Cochlea
 Makes 2 ½ turn
Inner EAR
 Vestibular Labyrinth
 3 semi circular canal
 Utricle
 Saccule

 Cochlea
 Makes 2 ½ turn
Inner EAR

 Membranous
Labyrinth
 Cochlear duct
(scala media)
 Attached to the inner
and outer walls of the
bony cochlea
creating 2 separate
ducts.
 Scala tympani
 Scala vestibuli
Inner EAR

 Scalatympani and
Vestibuli are
interconnected at
the cochlear apex
via the Helicotrema
Inner EAR

 Scalatympani and
Vestibuli are
interconnected at
the cochlear apex
via the Helicotrema
Inner EAR
Inner EAR
Blood Supply
 External ear
 Posterior auricular
 Superficial temporal arteries

 Middle ear
 tympanic branch of the maxillary (tympanic membrane)
 stylomastoid branch of the posterior auricular (posterior cavity
and mastoid)
 petrosal branch of the middle meningeal
 branch of the ascending pharyngeal,
 tympanic branch of the internal carotid
 branch from the artery of the pterygoid canal
Blood Supply
 Inner ear
 Labyrinthine artery (branch of anterior inferior cerebellar branch of
internal carotid artery)
Nerve Innervation
 External ear
 Auriculotemporal nerve
 Greater auricular nerve
 Middle ear
 Auriculotemporal nerve
 Tympanic nerve
 Auricular branch of the vagus nerve
 Inner ear
 Vestibulocochlear nerve (cranial nerve VIII)
Cochlea
Cochlea
Cochlea

Basilar Membrane

- thick at the base and narrow

at the apex

- together with the organ of corti it

forms the floor of the cochlear duct
Cochlea

Scala Media

- filled with endolymph

- ionic composition same as

intracellular space
Cochlea

Scala Vestibuli

- contains perilymph

- ionic composition same as

extracellular space
Cochlea

Reissner Membrane

- separates endolympahtic space

between scala media and scala
vestibuli
Cochlea

Scala Tympani

- filled with perilymph

- runs down from helicotrema to the
round window
Organ of CORTI

 Lies
on the inner
part of the basilar
membrane
Organ of CORTI

 Tectorial membrane

 An acellular structure
composed of amorphous
material and fibrils
 Covers the sensory cell
region of the corti organ.
Organ of CORTI

 Reticular Membrane

 Connects the ciliated

surfaces of the sensory
cells with one another
 Creates a partition
between the
endolympathic space
above the tectorial
membrane and
perilymphatic space
below
Organ of CORTI

 Hair Cells

 Mechanoreceptors
surmounted by a bundle
of stereocilia of varying
length on a specialized
surface
Organ of CORTI

 Inner hair cells

 > 3000 arranged in single

row along the cochlea
and connected to
several cochlear nerve
 Transforms acoustic
information into nerve
impulses
Organ of CORTI

 Outer hair cells

 > 12,000 arranged in 3

rows along the cochlea
 Their steriocilia are firmly
attached to the tectorial
membrane
 Few afferent connections
and are supplied mainly
by efferent cochlear
nerve fibers
 Peripheral Auditory System
 External EAR
 Middle EAR
 Inner EAR

Physiology of External EAR

 Transmits sound waves to the sensitive middle
ear structure in a discriminating way
Physiology of Middle EAR

A person in water can not hear sound produced

out of it.
As 99.9% sound get reflected from surface of
water due to Impedance.
So as Air filled Middle ear conduct sound to fluid
filled Inner ear most of sound get Reflected –
Impedance Mismatching.
Compensated by Inner Ear by – Impedance
Mismatching
 Physiology of Inner EAR
Outer Bony Labyrinth
1. Semicircular canal
 Contains cristea, site of Hair cells, maintains
static equilibrium
2. Vestibule
 Contains receptor for static equilibrium
 Maintains posture & balance
Membranous Labyrinth
 Filled with K+ rich fluid (endolymph)
 Sensory cells (Hair cells)
 Potassium ions generates the auditory signals
 It consist of 2 sacs
1. Utricle
2. saccule
 Physiology Of Hearing
1. Auricle/pinna direct sound waves into the external auditory
canal.
2. When sound waves strike eardrum that causes it to vibrate
3. The central area of the eardrum is connected to malleus which
starts to vibrate. Vibration is transmitted from malleus to incus
then to stapes.
4. As the stapes moves back & forth it pushes the membrane of
oval window in & out.
5. The movements of the oval window sets up fluid pressure waves
in the perilymph
6. So the vibrations are transmitted to “Organ of Corti” through
perilymph & endolymph.
7. From the Organ of Corti, the impulses (produced by vibrations)
are carried to brain through 8th CN to auditory centers of brain
which is present in temporal lobe.
Reading Material
Book
 Rudolf, M.D. Probst, Gerhard, M.D. Grevers, Heinrich, M.D. Iro,
Basic Otorhinolaryngology: A Step-by-Step Learning Guide,
2005

 https://b-ok.cc/book/927363/0868c3
Reading Material

 Assessment Tools: Introduction to the Anatomy

and Physiology of the Auditory System
 http://www.workplaceintegra.com/hearing-
articles/Ear-anatomy.html
VIDEOS

 Anatomy - Ear Overview

 https://www.youtube.com/watch?v=qYv9V2qna6

 Anatomy - Middle Ear

 https://www.youtube.com/watch?v=-
OuFKmZSZoY

 Ear Anatomy
 https://www.youtube.com/watch?v=sv7n-hEfBfA
VIDEOS

 How the Inner Ear Balance System Works -

Labyrinth Semicircular Canals
 https://www.youtube.com/watch?v=YMIMvBa8X
Gs
VIDEOS

 Inner ear Anatomy : Cochlear component,

Vestibular component, Semi-circular component -
Animation
 https://www.youtube.com/watch?v=XPHuiYInOsg
 ENT - Review of Anatomy
and Physiology of the Ear
and Nose and other
Important Face and Neck
Structures
OBJECTIVES

 To identify the major

structures & primary
functions of the nose
Anatomy of the Nose
Anatomy of the Nose

 External Nose
 Nasal Bone
 Lateral nasal cartilage
 Alar cartilage
Anatomy of the Nose

 External Nose
 Appearance of the nasal
tip and nares
 Medial and lateral crus
 Base of the nose
 Medial crura
 Inferior septal cartilage
Anatomy of the Nose

 Nasal Cavities

 is a large, air-filled space

above and behind the
nose in the middle of the
face
Anatomy of the Nose

 Nasal Cavities
 Piriform aperture
 (orange line)

 Superiorly: Nasal bone

 (blue line)

 Inf.&Lat: Maxillary
bone
 (yellow line)
 Anatomy of the Nose

 Nasal Cavities
 Nasal Septum:
 Consist of Cartilage &
Bones
 Quadrilateral
cartilage
 Perpendicular plate
of ethmoid
 Vomer
 Palatine bone
 Ant. Spine maxillary
bone
Anatomy of the Nose

 Nasal Cavities
 Nasal Septum:

 Divides the interior of

the nose to 2 main
cavities

 (LEFT
& RIGHT
NOSTRIL)
 Anatomy of the Nose

 Nasal Cavities
 Boundaries:
 Ant: Nasal vestibule
Anatomy of the Nose

 Nasal Cavities
 Boundaries:

 Lat: ethmoid and

maxillary bone
Anatomy of the Nose

 Nasal Cavities
 Boundaries:

 Post: palatine
bone and
pterygoid process
of the sphenoid
bone
Anatomy of the Nose

 Nasal Cavities
 Boundaries:

 Sup: cribriform plate

of ethmoid bone

 Floor: hard palate

Anatomy of the Nose

 Nasal turbinates
 Inferior turbinate
 Meatus: Opening of
nasolacrimal duct
 Middle turbinate
 Meatus: Maxillary sinus,
Anterior ethmoid and
frontal sinus
Anatomy of the Nose

 Nasal turbinates
 Superior turbinate
 Meatus: Posterior
ethmoid
 Blood supply
 External nose:
 External carotid artery: FACIAL ARTERY
 Internal carotid artery: OPHTHALMIC ARTERY
 Blood supply
 Internal nose:
 Sphenopalatine
artery/IMA/ECA

 Anterior & Posterior

ethmoid
arteries/Ophthalmic
artery/ICA
 Venous Drainage
 Internal nose:
 Anterior facial vein, Angular vein, Pterygoid plexus
Paranasal Sinuses
 Maxillary Sinus
 Present at birth
 Borders the nasal cavity laterally
 Superiorly: orbital floor (separates the sinus to the
orbit)
 Post. Wall of maxillary sinus: IMA
 Floor: closely related to the roots of 2nd premolar
and 1st molar teeth
 Ethmoid Sinus
 Superior and medial to maxillary sinus
 Small pneumatized cavities separated by thin
bony walls
 Extends posteriorly to the sphenoid sinus
 Lamina papyracea - separates the ethmoid to
orbit
 Posterior ethmoid cells – closely related to optic
nerve
 Roof: separates the ethmoid cells to anterior
cranial fossa
 Sphenoid Sinus
 Located at the approximate center of the skull
above the nasopharynx
 Posterior wall formed by clivus
 Sphenoid Sinus
 Laterally related to cavernous sinus. Internal
carotid artery, CN II-VI & optic nerve
 Bordered superiorly by sella turcica, pituitary gland
and ant & middle cranial fossa
 Frontal Sinus
 Located in the frontal bone
 Floor: forms medial portion of the orbital roof.
 Bounded behind the anterior cranial fossa
 Reach definitive size in the 1st decade of life
 Osteomeatal Unit
 Consist:
 Uncinate process
 Semilunar hiatus
 Frontal recess
 Ethmoid bulla
 Ethmoid infundibulum
 Maxillary ostium

 Bounded
 Medial: Middle
turbinate
 Lat: Lamina papyracea
 Osteomeatal Unit
 Main clinical
significance

 Relates to the sites of

narrowing in the OMC

 Due:
 Hyperemia and
Swelling
Morphology of the Nasal Mucosa

 Anterior third of the nasal cavity, Anterior portion

of the inferior and middle turbinates → SQUAMOUS
AND TRANSITIONAL EPITHELIUM

 Posterior 2/3 of the nasal cavity →

PSEUDOSTRATIFIED COLUMNAR EPIHTELIUM
Morphology of the Nasal Mucosa

 RESPIRATORY MUCOSA

 Cilliary cells
 Goblet cells
 Basal cells
 Provide initial mechanical
barrier against infection
Morphology of the Nasal Mucosa
 Nerve supply:
 Trigeminal nerve
(sensory)

 Pterygopalatine
ganglion
(autonomic)
Morphology of the Nasal Mucosa

 OLFACTORY MUCOSA

 Located
 anterior superior part
of the nasal septum

 adjacent areas
lateral nasal wall

 sides of superior
turbinate (facing the
septum)
Morphology of the Nasal Mucosa

 OLFACTORY MUCOSA

 Detects odor-producing
chemicals.

 It includes specialized
nerve cells and non-
motile cilia to provide a
binding site for odorants.
 Basic Physiology and Immunology of the
nose

Physical principle of nasal airflow

 INSPIRATION →reaches nasal valve

→ limen nasi → turbulent airflow →
slows velocity of the inspired air →
prolongs contact with nasal
mucosa → contribute to olfaction
→ humidify and warm the inspired
air → lower airway
Basic Physiology and Immunology of the
Nose
 FUNCTIONS OF THE
NOSE

 HUMIDIFICATION

 PROTECTION

 SPEECH PRODUCTION

 OLFACTION
Basic Physiology and Immunology of the
nose
 PROTECTIVE FUNCTION OF NASAL MUCOSA

 Non specific Defense Mechanism

 Specific Immune Mechanism

Basic Physiology and Immunology of the
nose
 Non specific Defense mechanism
 Mechanical defenses
 MUCOCILLIARY APPARATUS (2 LAYERS)
 Superficial layer – GEL LAYER ( traps bacteria
and particulate matter)
 Deep layer – SOL LAYER (ciliary motion
occurs)
Basic Physiology and Immunology of the
nose
 Non specific Defense mechanism
 Nonspecific protective factors (Mucous blanket)
Basic Physiology and Immunology of the
nose
 Non specific Defense mechanism
 Cellular defenses
 Phagocytic activity
 NEUTROPHILIC GRANULOCYTES
 MONOCYTES
 MACROPHAGES

 Accompanied by NK cells
 Protect
against viral infections of the nasal
mucosa
 Basic Physiology and Immunology of the
nose
 Specific immune response
 Humoral immune response

IgA characteristic of resp. mucosa (secretory

antibodies)

 isan antibody that plays a crucial role in the

immune function of mucous membranes
 Basic Physiology and Immunology of the
nose
 Specific immune response
 Cellular immune response
 T-lymphocytes:
memory function of
immune response
 B-lymphocytes:plasma cells,
humoral response
 Basophilic granulocytes and mast
cells: involve in immediate allergic
reactions
 Epithelialcells: acts as receptor for
rhinoviruses 90% of the time
Basic Physiology and Immunology of the
nose
 SPEECH PRODUCTION

 Hyponasal speech:
 Contributes to less sound production
 Due to partial or complete nasal obstruction

 Hypernasal speech:
 Nasopharynx and nasal cavity overcontribute to sound
production
 Abnormal resonance in a human's voice due to increased
airflow through the nose during speech
 Ex. Cleft palate
OLFACTORY PATHWAY

• Olfactory nerves
• Olfactory bulb
• Olfactory tract
• Anterior olfactory nucleus
• Olfactory striae
• Olfactory cortex
Odoriferous stimuli
 enters the nasal cavity while breathing, then it
reaches lower part of nasal cavity, & by eddy
currents reaches
olfactory mucosa.

Odorant molecules must dissolve in mucus

layer before receptors
CHARACTERISTIC
FEATURES
OF ODORANT MOLECULES
To be effective odorant molecules must
be:

• Volatile

• Water soluble

• Lipid soluble
TYPES OF ODORANT
STIMULI
• 50 primary smell sensations( 3 primary color, 4 taste
sensation)

• Can smell over 10000 different odorant molecules

COMMON ODOURS

 Aromatic/resinous – camphor, lavendor, clove

 Fragrant – perfumes, flowers
 Ethereal – ether, chloroform
 Garlic – garlic, onion, sulphur
 Burning – tobacco, meat , bones
 Nauseating – excreta, decomposed meat, veg
 Goat – sweat, ripe, cheese
 Repulsive – bed bug
 Musky – musk
Reading Material

Book
 Rudolf, M.D. Probst, Gerhard, M.D. Grevers, Heinrich, M.D. Iro,
Basic Otorhinolaryngology: A Step-by-Step Learning Guide,
2005

 https://b-ok.cc/book/927363/0868c3
 Anatomy and Physiology of the Nose
 https://www.youtube.com/watch?v=B_n7dnxVkO
M
the Ear and
Nose and other
Important Face
and Neck
Structures
OBJECTIVES

 To identify the triangles of the neck and their

boundaries
 Development
 skin of the neck is derived from cervical
dermatomes which arise from the second to the
sixth cervical segments
 The sternocleidomastoid, strap muscles and
trapezius originate from cervical myotomes
Triangles

Anterior triangle
1. submental
11. submandibular
111. carotid
1V. Muscular
Posterior triangle
1. lateral neck
2. 11. subclavian
Anterior triangle

 The boundaries of this triangle are

sternocleidomastoid, the inferior ramus of the
mandible and the midline.
Contents
 Muscles – diagastric, stylohyoid, mylohyoid, sup belly
of omohyoid, strap muscles.
 Vessels – external carotid branches ( except post
auricular ), internal & anterior jugular vein &
tributaries.
 Nerves – internal & external laryngeal, nerve to
mylohyoid, hypoglossal nerve. Viscera – thyroid &
larynx, submental & sub mandibular glands. Other
– jugular chain of lymph nodes
Submental triangle

 The boundaries are the anterior belly of the

digastric, midline and hyoid bone
 contains lymph nodes and the submental salivary
gland
Submandibular triangle

 The boundaries are the inferior margin of the

mandible and the anterior and posterior bellies of
the digastric muscle.
 The deep boundary consists of the stylohyoid and
mylohyoid muscles.
 Contains the submandibular salivary gland, deep
fascia, lymph nodes, anterior facial vein, facial
artery and the marginal mandibular branch of the
facial nerve
Carotid triangle

 The boundaries are the anterior border

sternocleidomastoid, posterior belly digastric and
the superior belly of omohyoid.
 It contains the upper carotid sheath and lymph
nodes
Muscular triangle

 The boundaries are the lower anterior border

sternocleidomastoid, anterior belly omohyoid, the
hyoid bone and the midline.
 Contains the lower carotid sheath, the infrahyoid
strap muscles, upper aero digestive tract, the
thyroid and parathyroid glands.
Posterior triangle

 The posterior triangle can be divided into two by

the omohyoid, which forms the lateral neck
triangle and the subclavian triangle. Contents
 Muscles – omohyoid
 Vessels – occipital, transverse cervical,
suprascapular, subclavian arteries & transverse
cervical, suprascapular external jugular veins.
 Nerves – cervical & branchial plexus
 Other – lymph nodes
Lateral neck triangle

 The boundaries are the posterior border of the

sternocleidomastoid, the anterior border of the
trapezius and the superior border of the inferior
belly of the omohyoid muscle
 Contains the cervical plexus, fibrofatty tissue,
lymph nodes and the accessory nerve
Subclavian triangle

 The boundaries are the lower border of the inferior

belly of omohyoid, the clavicle and the posterior
border sternocleidomastoid
 Contents are fibrofatty tissue, the scalene
muscles, the brachial plexus and the subclavian
vesseIs, including the thyrocervical trunk
 Also included are Sibson's suprapleural fascia and
the pleura
VIDEOS

 Triangles & Subdivisions of the Neck – Head and

Neck Anatomy | Lecturio
 https://www.youtube.com/watch?v=Em16byf8Px
M
 Carotid triangle - boundaries & contents |
Anatomy Tutorial
 https://www.youtube.com/watch?v=LQDFQb2Zhs
E