Anatomy of pharynx /certified fixed orthodontic courses by Indian dental academy

ANATOMY OF
PHARYNX AND LARYNX AND
APPLIED ASPECTS OF
PHARYNX AND LARYNX
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

contents
Pharynx

Anatomy

Development

Divisions

Muscles

Pharyngel tissue spaces

Innervation

Arterial supply

Venous supply

Lymphatic drinage

Functions

Applied aspects

Examination of the pharynx


Larynx

development


Anatomy

Cartilage

Ligaments
Fibrous membreane



Joints
Muscles









Laryngeal cavity
Para lumenal spaces
Vascular supply
Lymphatic drinage
Innervation
Clinical aspects
Functions

 Cephalometrics related to pharnyx
 References


Pharynx


Fibro muscular tube
Attached to the base of the
skull
Continuous with the
esophagus inferiorly


Structures of the pharynx
 Has a wall consists of 4 layers
1-mucosa
2-pharyngobasilar fascia
no submucosa,so even slight edema will result in a painful
‘’ sore throat’’
3-muscular coat
-externally pharngeal costrictor muscle
-internally longitudinal muscle
4- buccopharyngeal fascia
 Contains pharyngeal plexus


Development


Pharyng
eal Arch

Cranial
Nerve

Muscle
derivativ
e

Skeletal
Derivativ
e

1
Mandib
ular

Trigemin
al nerve

Muscle of
masticatio
n
Tensor
tympani

Incus,
ant. Lig
of
malleus

Facial
nerve

Muscles
of facial
expressio
n

Stapes,
Hyoid
bone

2
Hyoid

3

Glossoph stylophary Horns of
aryngeal ngeas
hyoid
nerve

4

Vagus
nerve

Striated
muscles
of
oesophag
us

5

None

none

6

Merges
with 4

none

9

Pharyn
geal
Pouch

Derivative

1

Epithelium of
tympanic cavity and
auditory tube

2

Epithelium of tonsil

3

Inferior parathyroid
glands and
epithelium of
thymus

4

Superior
parathyroid glands.

10

Pharyngeal
(grooves):

Clefts

located
arches

between

these are spaces, thus
contain no germ layer
components
initially 4 clefts of
which only one develops
as 2nd
arch grows over
all other clefts filling them
in
1st cleft forms the
External
Auditory
Meatus

11

Divisions




nasopharynx
oropharynx
hypopharynx


Nasopharynx
-extends from the base of the
skull to the soft palate
-functionally a part of the
respiratory system
-remains open at all times
Anterior
nasal choanaenasal cavity
Posterior and superior
body of the sphenoid ,basilar
occipital bone and the arch of
the atlas
Floor-soft palate
Inferiorly-communicates with
the
oropharynx
at
the
pharyngeal isthmus.

Pharyngeal tonsils
-includes
a-pharyngeal tonsils
b-auditory tube
embedded in the mucosa of
the posterior wall of the
Nasopharynx.
may impair breathing when
enlarged and are then called
adenoid.


Oropharynx

 extends from the soft palate
above
 to the upper border of epiglottis
below
 at the level of the bodies of the
C2 and C3 vertebrae
 anterior  the base of the
tongue
 inferior

the epiglottis
(uppersurface of the larynx)
a-median glossoepiglottic fold
b- lateral glossoepiglottic folds
c- the
vallecular recess(3rd branchial
pouch)
 contains palatine tonsils
a- the faucial pillars (arch or fold)
b- the tonsillar fossae (2nd
branchial pouch)

a- the faucial pillars (arch or fold)
 palatoglosus (anterior),
palatopharyngus (posterior)
b- the tonsillar fossae
 triangular-shaped
 muscular bed formed by superior
pharyngeal constrictor muscle
 contains a mass of lymphoid
tissue (palatine tonsil)
 lie b/w the diverging fauces on
each sides in space b/w the
superior and middle pharyngeal
constrictor muscle
posteriorly middle pharyngeal
constrictor Muscle and stylohyoid
ligament
anteriorlyhyoglossus muscle

stylopharyngeus muscle carries
glossopharyngeal nerve b/w
the superior & middle const.m
(the nerve is at risk during
tonsillectomy)
 extends from the base of the
tongue to the edge of the soft
palate
 medial surface
intratonsilar cleft + 12-15 tonsillar
crypts
 lateral surface
fibrous tonsillar capsule derived from
the pharyngobasilar fascia
 easly
separated
from
the
pharyngeal wall
 except at the root of the tongue
(tonsillar arteries enterance)


Blood supply of the tonsils
 Tonsile branches of
1- Lesser Palatine (maxillary
artery)
2- Ascending Palatine ( facial
artery)
3- Lingual artery (ECA)
4- Ascending Pharyngeal artery
(ECA)
5- Facial artery (main source)
(ECA)
 Venous drainage of tonsil
peritonsillar venous plexus
tonsillar branch of the lingual vein
(main vein)source of a profuse
venous hemorrhage after
tonsillectomy

Hypopharynx
 extends from the upper border of
the epiglottis to the lower border of
the cricoid cartilage where it
continuous with the esophagus at
the level C4,5,and 6 vertebrae
 It has anterior wall,posterior wall
and lateral walls
 In lateral wall there is a depression
called piriform fossa


Piriform recess
 inferior to the lateral
glossoepiglottic folds on
either side of the larynx
food and liquid are
diverted to either side of
the larynx into these
recesses upon deglutition
 swallowed foreign bodies
may lodge in these
recesses
 internal laryngeal nerve
can be anesthetized
where it lies deep to the
mucosa of the piriform
recess

Muscles of the pharynx
 3 pairs overlapping
constrictors
 3 pairs diagonal muscles
 constrict the pharyngeal
lumen to propel food and
drink when swallowing
1-Superior constrictor
2-Middle constrictor
3-Inferior consrictor

 lamina of thyroid cartilage
and cricoid pharyngeal
raphe


Cricopharyngeal muscle
 functions as a sphincter
 at the superior end of the
esophagus
( i.e. b/w pharynx and
esophagus)
 faliure of the
cricopharyngeaus to relax
during swallowing
occasionally causes the
mucosa to herniate
through the inferior
constrictor , forming a
pharyngeal diverticulum

Longitudinally arranged muscle
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palatopharyngeus m
salpingopharyngeus
stylopharyngeus m



Arise at base of skull and
descend b/w pharyngeal
constrictor and
pharyngobasilar fascia to
insert into fascia and thyroid
cartilage


PHARYNGEAL TISSUE SPACES
 Sub-divided into peripharyngeal and intrapharyngeal
space
 Peripharyngeal divides into anterior,posteriorly,and
laterally
 Anterior-it is formed by submandibular and submental
space.
 Posterirly by the retropharyngeal space.
 Laterally by para pharyngeal space.
 Peritonsillar space is an important part of the intra
pharyngeal space


Nerve supply of pharynx
pharyngeal plexus
 Provided most of the innervation to the pharynx
 Lies in the buccopharyngeal fascia
 covering the outer surface of the pharyngeal constrictor
muscle
 Supplies the
1-muscles of the pharynx except the stylopharyngeus
2-muscles of the palate except the tensor veli palatini
3-mucosa of the pharynx and cartilagenous portion of the
auditory tube except part of the roof (phary.br. of V2)


Blood supply of the pharynx
derived chiefly from
 the Ascending pharyngeal artery
 small branch. Of ECA near its origin ascends b/w pharynx
and the ICA
Also is supplied regionally by the
 1- ascending palatine artery from the facial artery
 2- superior thyroid artery
 3- inferior thyroid artery


FUNCTIONS O THE PHARYNX
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Respiration
Deglutition.
Phonation.
Protective function


deglutition
 Deglutition = Swallowing
 Deglutition is the complex
process that moves bolus
of food from mouth
through pharynx into
esophagus and then to
stomach


Organs of deglutition and related
structures
 During deglutition, the muscles of
mouth, pharynx, larynx and
esophagus coordinate properly in
a complex process; to move food
and liquid into stomach
 Organs of deglutition
 Oral cavity
 Pharynx
-Nasopharynx
-Oropharynx
-Laryngopharynx

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

Esophagus
Stomach
The airway is protected by correct movement of larynx, so
that food and liquid does not enter the airway


Stages of deglutition
 • Deglutiton is a
continuous process from
oral cavity to stomach,
divide into 3 stages
 1.oral phase
 2.pharyngeal phase
 3.esophageal phase


Oral phase
 First stage of deglutition
 • The first stage is
voluntary and initiate
deglutition process
 – A mass of chewed,
moistened food, a bolus, is
moved to the back of the
oral cavity by the tongue
 – The lip and buccal
muscles help keep bolus
from dispersing either
anteriorly out of oral cavity
or laterally into oral
vestibule

Second stage of deglutition
 Second stage of
deglutition
 The second stage is
involuntary and rapid
 The entire process occurs
in less than 2 seconds
 Start from the point at
where the deglutition reflex
is triggered at the anterior
faucial arch through the
upper esophageal
sphincter into the
esophagus

 The bolus is propelled by
pumping action of tongue
base and constriction of
pharyngeal muscles
 Anterior faucial arch
 Soft palate
 Palatoglossal arch
 Base of tongue


Pharyngeal phase
 Pharyngeal phase
 Soft palate is elevated,
sealing off the
nasopharynx from
oropharynx, prevent reflux
of food into nasal cavity
 Initiation of pharyngeal
peristalsis to pick up and
carry the bolus


 Elevation and closure of
larynx, to prevent food
from entering airway
 Upper esophageal
sphincter (cricopharyngeus
muscle) relaxation


Pharyngeal phase
 Larynx is closed off to the bolus
by several mechanisms:
 Larynx is pulled upward and
anteriorly by muscles of neck,
cause epiglottis to swing
backward over the opening of
larynx.
 Closure of larynx at all 3
sphincters
Epiglottis / aryepiglottic folds
 False vocal folds
 True vocal folds
 Cessation of respiration

Third stage of deglutition
 The third stage is also
involuntary
 8-20 seconds transmit time
 Start from the point where
the bolus enters the
esophagus at the upper
esophageal sphincter
 Until the bolus passes into
stomach at the lower
esophageal sphincter
 During third stage,
combination of gravity and
peristalsis, push the bolus
from esophagus down to

Deglutition

Oral phase (a)
Pharyngeal phase (b)
Esophageal phase (c),(d),(e)

Deglutition reflex

 Deglutition reflex
 Deglutition reflex is mainly
a protective reflex
 Two main things take
place during reflex
 A squeezing action
squeezes the bolus with
muscles that pull food
down to the stomach. This
action is called peristalsis.
 Larynx closes off to keep
food out of the airway. The
epiglottis folds down and
the vocal folds shut. www.indiandentalacademy.com

Deglutition reflex
 Sensory impulses
transmitted as a result of
stimulation of deglutition
receptors on the fauces
 Tonsils
 Soft palate
 Base of tongue
 Posterior pharyngeal wall
 By the 7th, 9th and 10th
cranial nerves

Deglutition reflex
 Sensory impulses reach
the deglutition center in
brain stem
 Motor function is mediated
through the 5th, 9th, 10th
and 12th cranial nerves
 To initiate muscle
contraction
 Elevation of soft palate
 Elevation and closure of
larynx
 Peristalsis of pharynx and
esophagus.

EXAMINATION OF THE PHARYNX
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Examination of the nasopharynx:
Post-nasal mirror (posterior rhinoscopy).
Flexible fiberoptic endoscopy (under local anesthesia).
Rigid endoscope introduced through the nose or mouth
(under L.A. or G.A.) using different angles (0°, 30°, 70°, or
90°.
Examination of the oropharynx:
Examination is done through an open mouth with tongue
depressor.
Digital palpation whenever malignancy is suspected.
Examination of the laryngopharynx (hypopharynx):
By indirect laryngoscopy (using laryngeal mirror)
By flexible nasolaryngoscope.
By rigid endoscope (90° or 120°).
By direct laryngoscopy under general anaesthesia.

INVESTIGATIONS OF THE
PHARYNYX
 Plain X-ray
 Barium swallow
 CT scan and MRI
 Angiography
 Contrast fluoroscopy

APPLIED ASPECT
1. TONSILLITIS:
Generally due to streptococcal
infection.
Generally treated conservativily
with antibiotics.
Chronic or recurrent cases may
require surgical removal or
tonsillectomy
2. TONSILLECTOMY:
Most
common
postoperative
complication- hemorrhage


3. ADENOIDITIS:
infection and inflammation
of the pharyngeal tonsils or
adenoids –
-block
the
orifice of the auditory tube
pain
and
temporary deafness
4.
PHARYNGEAL
DYSPHAGIA
5. VAGAL REFLEXES

Larynx


Development
 Internal lining from endoderm ,as well as the laryngeal
epithelium and glands
 Muscles and cartilage from 4th&6th pharyngeal arch
 At week4,on the ventral side of the primitive gut,a pocket
forms that bulges out from the gut-laryngo tracheal
diverticulum
 Ant(ventrally)=laryngeal tracheal tube
 Post(dorsally=eosphageal tube
 Opening of laryngeal diverticulum=orifice
 Epiglottis and cuneiform cartilages are derived from 4th
arch.
 Cricoid,arytenoid,corniculate are developed from 6th
th

th

Laryngeal skeleton
 Is a cartilaginous
framework that is firmly
anchored to the hyoid
bone
 Moves up or down with
movement of the hyoid
bone
Consists of
the paired
– arytenoid,
– corniculate
– cuneiform cartilage
the unpaired
–
thyroid
–
cricoid
–
epiglottic cartilages

Thyroid cartilage
 Is the largest of the
laryngeal cartilage
 Paired Lamina
meet in the midline
anteriorly at laryngeal
prominence, but
diverge posteriorly


On their outer surface have an oblique line

 for attachment of
1. inferior pharyngeal
constrictor
2. Sternothyroid
3. thyrohyoid muscles


Cricoid cartilage

 Is an unpaired hyaline
cartilage
 Is ring shaped having a
narrow anterior arch and a
wide posterior lamina
 Lies at the level of the
sixth cervical vertebra
Is connected
Superiorly

to the thyroid cartilage
by way of the cricothyroid
joint
and the cricothyroid
membrane
Inferiorly

to the first tracheal ring
by way www.indiandentalacademy.com
of the
cricotracheal ligament

Epiglottic cartilage
 Is a leaf-shaped
cartilaginous plate
 Lies posterior to the root of
the tongue
 Anterior surface is
connected to the tongue
by median glossoepiglottic
fold.
 Posterior surface is
covered with mucous
membrane.

Arytenoids cartilage
Is pyramid shaped&paired
Sits on the superior surface
of the cricoid lamina
Has an apex Supports the
corniculate cartilage
within the aryepiglottic fold
Has a base Forms a synovial
joint with the lamina of the
cricoid cartilage
Has a muscular process
Provides attachment for the
lateral
cricoarytenoid,
posterior
cricoarytenoid,
and
thyroarytenoid
muscles
Has a vocal process
Provides attachment for the
vocal ligament and vocalis
muscle

Corniculate cartilage
Is a paired elastic cartilage
that rests on the apex
of the arytenoid cartilage
Lies within the aryepiglottic
fold of mucous membrane
Cuneiform cartilage
Is a paired elastic cartilage
that lies in the aryepiglottic
fold superior to the
corniculate cartilage

Ligaments and membranes of the
larynx
Thyrohyoid membrane
 Is a tough, fibrous
membrane that connects
the upper border of the
thyroid cartilage to
the lower border of the
hyoid bone
 Its lateral portion is pierced
by the internal laryngeal
nerve and
superior laryngeal artery

Cricothyroid membrane
 Inferiorly to the arch of the
cricoid cartilage
 Superiorly to the deep
surface of the thyroid
cartilage and to the vocal
process of the arytenoid
Cartilage
 Is thickened Along its free
upper border to form the
vocal ligament
 In the midline to form the
median cricothyroid
ligament
 Extend upward deep to
thyroid cartilage as conus
elasticus


Vocal ligament
 Extends between the deep
surface of the thyroid
cartilage and the vocal
process of the arytenoid
cartilage
 Is the thickened free
border of the conus
elasticus portion
of the cricothyroid
membrane


Quadrangular membrane
 It forms the lateral wall of
vestibule with free margins
forming aryepiglottic and
vestibular fold
 Connects the arytenoid
cartilage and the epiglottic
cartilage
 Lies in the lateral wall of the
vestibule separating
it from the piriform recess
Vestibular ligament
– Is the free lower border of
the quadrangular
Membrane
– Lies in the vestibular fold

Laryngeal cavity and folds
 three distinct parts
 is divided by the
vestibular folds and
ventricular folds
– the vestibule
– the ventricle
– the infraglottic cavity,


Vestibule


Lies between the
laryngeal aditus and the
vestibular folds

 Aditus
Is the entrance from
the pharynx into the
larynx
 Rima vestibuli
space between the paired
vestibular folds


Vestibular fold-false vocal folds
 Paired transverse fold
lying on the side of the
larynx
 Extends from the thyroid
cartilage to the arytenoid
cartilage above the vocal
fold
 Contains
 Vestibular ligament
 Upper fibers of the
thyroarytenoid
muscle
 Closes to protect the
airway during swallowing
and during forced
expiration against a
closed airway

Ventricle
 Is a boat-shaped
depression
 Extending laterally
between the vestibular fold
and the vocal fold
 Contain glands that
lubricate vocal fold ( as
vocal folds by themselves
lack mucous glands )
 May extend superiorly in
anterior part as saccule of
variable size


Vocal folds
 Lies inferior to the vestibular
fold and extends between
the thyroid cartilage and the
vocal process of the
arytenoid cartilage
 Contains the
– Vocal ligament (no
submucosa-excluding
edema)
– Vocalis portion of the
thyroarytenoid muscle

 Functions to
– Control the flow of air through the rima glottidis
– Produce the sounds of speech


Rima glottidis

 Interval
between
the
paired vocal folds
 Narrowest part of the
laryngeal cavity
 Opens and closes to
regulate the passage of air
• Obstruction
of
the
laryngeal airway at the
rima glottidis may result
from aspirated food
such as a piece of meat


Glottis


Infraglottic cavity
 Lies between the vocal
fold and the lower border
of the cricoid cartilage
 Is continuous inferiorly
with the trachea
 Is related anteriorly to
the cricothyroid
membrane
 An emergency airway
made through the
cricothyroid membrane
will enter the airway
below the vocal folds
where obstruction of the
airway most commonly
occurs.

Vocal folds
during a vibratory cycle
Open for
breathing


Extrinsic Muscles of the Larynx
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Elevators
Stylohyoid
Mylohyoid
Geniohyoid
Genioglossus
Hyoglossus
Inferior laryngeal
constrictor
Digastric
Depressors
Sternothyroid
Sternohyoid
Omohyoid
Thyrohyoid
Other
Cricopharyngeus


Extrinsic Muscles elevate and depress the larynx
 Lift larynx during swallowing
 Minimal vertical excursion during normal speech


Intrinsic Muscles of the Larynx
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Adductors
Lateral cricoarytenoid
Transverse arytenoid
Oblique arytenoid
Abductor
Posterior cricoarytenoid

Tensors
 Medial thyroarytenoid
 Cricothyroid
Relaxers
 Lateral thyroarytenoid

Posterior Cricoarytenoid
 Only abductor muscle
 Origin posterior surface of
cricoid
 Angles up to insert in
muscular process of
arytenoid on same side
 Rotates vocal process
laterally
 Innervated by recurrent
laryngeal nerve


Lateral Cricoarytenoids
 Adductors
 Functions as direct agonist
to posterior cricoarytenoid
 Origin in upper border of
cricoid arch and inserts
onto muscular process of
arytenoid on same side
 Rotates muscle process
forward and causes vocal
process to ‘toe in’ at
midline


Transverse Arytenoids
 Adductors
and
fold
compressors
 Only unpaired intrinsic
muscle of larynx
 Origin in lateral margin of
one
arytenoid
and
traverses the distance to
the same spot on the other
 Approximate bodies of
arytenoids together
 Innervated by recurrent
laryngeal nerve

Oblique Arytenoids
 Adductors
 Origin
in
muscular
process of one arytenoid;
inserts on apex of the
other
 Fibers continue to lateral
border of epiglottis -->
aryepiglottic folds
 Active during swallow &
bring vocal cords closer
together
by
approximating apex


Thyroarytenoid Muscles
 Tensors
 Form bulk of muscular
portion of folds
 Origin from inner surface
of thyroid; insert in vocal
process and lateral
surface of arytenoids
 Shorten to lower pitch;
also adduct glottis by
muscular tension and
elasticity


Cricothyroid Muscles
 Tensors
 Origin in anterior-lateral arch of
cricoid; insert a) near lower horn
of thyroid & b) lower margin of
lateral thyroid wall
 Innervated by external branch of
superior laryngeal nerve ( only
intrinsic muscle not innervated by
recurrent laryngeal nerve )
 Increases
distance
between
thyroid and arytenoid cartilages,
increasing pitch by stretching
folds
 Tense folds by lengthening them

Actions of Intrinsic muscles
 Cricothyroid tenses and
lengthens the vocal lig.
 Posterior cricoarytenoid 
abduct (OPENS )
 Lateral cricoarytenoid 
adduct (CLOSE)
 Transverse arytenoid adduct
(CLOSE)
 Oblique arytenoidsadduct
(CLOSE)
 Thyroarytenoid  decreases
the tension & length
 Vocalis (portion of the
thyroarytenoid lying within the
vocal fold)

Innervation of the larynx
 Superior laryngeal nerve
 Recurrent laryngeal nerve


Innervation of larynx (makes surgery
at neck risky
– Recurrent laryngeal nerves of
Vagus
– These branch off the Vagus
and make a big downward loop
under vessels, then up to
larynx in neck
– Left loops under aortic arch
– Right
loops
under
right
subclavian artery
– Damage to one: hoarseness
– Damage to both: can only
whisper


Functions of larynx
 Biological roles of larynx
– prevents foreign
bodies from entering
airway
– fixates thorax by
stopping airflow at
glottis level,
permitting heavy
lifting/weight
supporting feats


Examination of larynx
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INDIRECT LARYNGOSCOPY
FLEXIBLE AND RIGID ENDOSCOPES
STROBOSCOPIC EXAMINATION
DIRECT LARYNGOSCOPE


INDIRECT LARYNGOSCOPY


FLEXIBLE ENDOSCOPY


RIGID ENDOSCOPES


STROBOSCOPIC EXAMINATION


DIRECT LARYNGOSCOPE


CLINICAL ASPECT


CLINICAL CONSIDERATIONS IN
ORTHODONTIA

Cephalometrics – pharyngeal
relationships


variables
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AA-PNS
Ap-Ptm
apw2-ppw2-pharyngeal depth
apw4-ppw4-pharyngeal depth
Ba-PNS-dimension of the bony pharynx
Ip-Kp-smallest distance
Mp-Lp-smallest distance
N-S-Ptm-shape of the bony nasopharyngeal space
P1
P2
P3
Ptm-PPW-depth of nasopharynx






Ptm-SWP-height of nasopharynx
Ptm-s-Ba-shape of the bony nasopharyngeal space
T1-soft tissue shadow
T2


Mcnamara analysis


Upper pharyngeal space




Lower pharyngeal space


References
 Gray’s Anatomy, 38th edition
 A. K. Datta – Essentials of human anatomy, head and
neck.
 Dhingra – Diseases of ENT 4th edition
 B.D. Chaurasia – Human Anatomy, head and neck, 4th
edition.
 Athanasiou – Orthodontic Cepahlometry
 Grant’s Atlas of Anatomy 10th edition
 Jacobson – Radiographic Cephalometry 2nd edition.
 Agur dalley-Grants atlas of anatomy 12th edition


 Anatomical basis of dentistry by liebgott 2nd edition
 Snell clinical anatomy for medical students.


Anatomy of pharynx /certified fixed orthodontic courses by Indian dental academy

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