THE PHARYNX pdf - د. علي

Is a funnel-shaped fibromuscular tube,

10-12 cm in length in adults. It extends from
the base of the skull superiorly to the
oesophagus at level of C6. The
pharyngeal wall consists of 4 layers:

1. Mucous membrane.

2. Pharyngobasilar fascia.

3. Muscle layer.

4. Buccopharyngeal fascia

Pharyngeal Wall

The pharynx is divided anatomically
into 3 parts defined by the openings

of its anterior surface; nasopharynx,

oropharynx and laryngopharynx

Behind

The Nose

The Mouth

The larynx

Anatomy of the pharynx

Compartments

•

Nasopharynx

•

Oropharynx

•

Laryngopharyn

•

(Hypopharynx

)

Seen from behind

Nasopharynx:

This extends from the

base  of  the  skull  to  the  soft  palate.  At
the  junction  of  the  roof  and  posterior
wall lies a small mass of lymphoid tissue
called adenoids (nasopharyngeal tonsil).
On  the  lateral  wall,  there  are  the
openings  of  the  Eustachian  tubes.
Behind  which  are  hollows  called  the

fossa of Rosenmuller

, which is the site

of nasopharyngeal malignancy.

Nasopharynx

Behind the nasal cavity

Extends from skull

Base superiorly to the
hard palate inferiorly

Communicates

inferiorly with the

oropharynx through the

velo-pharyngeal

sphincter

The nasopharyngeal

tonsil lies in the roof

The pharyngeal opening

of ET lies in the lateral

wall

2. Oropharynx

: This extends from the

level of soft palate to the upper border of
epiglottis and opens anteriorly into the
oral cavity. The palatine tonsils are
situated in it's lateral wall.

Hypopharyx:

This extends from the tip

of  epiglottis  to  the  upper  end  of
oesophagus  and  communicates  anteriorly
with  the  larynx  and  below  with  the
oesophagus. It’s divided into 3 parts:

a. Pyriform fossae

: are two potential spaces on

each side of the pharynx forming a lateral food
channel during the act of swallowing.

b. Postcricoid area:

lies behind the cricoid

cartilage and encircled by the cricopharyngeus
muscle which forms the upper oesophageal
sphincter.

c. Posterior pharyngeal wall

: extends from the

hyoid bone to the oesophageal inlet.

Oropharynx

Behind the oral cavity

(in front of

Cervical vertebra)

From the soft palate superiorly to tip

of epiglottis inferiorly

Communicates:

Anteriorly with the oral cavity

Superiorly with the nasopharynx
Inferiorly with the hypopharynx

The paatine tonsils lie laterally
between the anterior and posterior
pilars

Hypopharynx

Behind the Larynx

(in front of

to 6th Cervical vertebra)

From the tip of epiglottis superiorly

the lower border of cricoid cartilage
Inferiorly

Communicates:

Anteriorly with the Larynx

Superiorly with the oropharynx

Inferiorly with the esophagus

The hypopharynx does not only
lie behind the larynx BUT also

Projects laterally on each side of

the larynx

So it is formed of :

Postcricoid region ( behind

the larynx)

Two pyriform fossa (on

each side of the larynx

Seen from

behind

Cross section

The lining epithelium is stratified squamous

except in the nasopharynx, where
columnar epithelium is found.

This fascia is strengthened posteriorly by a

strong band called the median raphae.
This raphae is attached above to the base
of the skull and gives insertion to the
constrictor muscles.

I-

Circular (outer):

which consist of 3

constrictor muscles overlapping one
another from below upwards.

1. Superior constrictor

: it arises from the

medial pterygoid plate, pterygoid hamulus
and pterygomandibular ligament.

2. Middle constrictor

: it arises from the

hyoid bone and stylohyoid ligament.

3. Inferior constrictor

: has 2 parts:

a. Thyropharyngeus (oblique): arises from

the oblique line of thyroid cartilage and
the cricothyroid muscle.

b. Cricopharyngeus (transverse): arises from

the cricoid cartilage and passes
transversely backwards forming the
upper oesophageal sphincter.

All the constrictor muscles are inserted

posteriorly into the median pharyngeal
raphae.

Functions

The constrictor muscles propel the bolus of

food down into the esophagus

Cricopharygeus (lower fibers of the inferior

constrictor) act as a sphincter, preventing
the entry of air into the esophagus
between the acts of swallowing

Muscles of the Pharynx

Killian dehiscence

: this is a potential gap

between the fibers of the thyropharyngeus
and

cricopharyngeus.

The

mucous

membrane may bulge between these two
muscles  when  there  is  incoordination  of
the  pharyngeal  peristaltic  waves  (the
cricopharyngeus  doesn’t  relax  at  the
appropriate  time  during  the  2nd  stage  of
deglutition)  forming  the  pharyngeal
pouch.

Pharyngeal Pouch

II-

Longitudinal (internal):

these

muscles elevate the larynx and shorten
the pharynx during deglutition:

1. Stylopharyngeus.

2. Salpingopharyngeus.

3. Palatopharyngeus

This fascia is loosely attached posteriorly

to the prevertebral fascia and laterally it's
connected to the styloid process and to
the carotid sheath.

Subepithelial lymphoid tissue of the

pharynx (Waldeyer's ring)

Is a collection of sub-epithelial lymphoid

tissue around the entrance of the
respiratory and alimentary tracts.

Nasopharyngeal

tonsil

(adenoid): Lies between the roof
and

posterior

wall

the

nasopharynx.  The  free  surface
exhibits about 5 vertical fissures.
2.  Tubal  tonsils:  lie  behind  the
openings of the Eustachian tubes.
3.  Palatine  tonsils:  are  two
masses  of  lymphoid  tissue  situated
on each side of the oropharynx.

4. Lingual tonsils: which is
embedded in the posterior 1/3 of the
tongue.
5. Lateral pharyngeal bands
behind the posterior tonsillar pillar.
6. Lymphoid nodules scattered on
the posterior pharyngeal wall.

Waldeyer

s Ring

Hypertrophy  of  the  lymphoid  tissue
of  Waldeyer's  ring  occurs  in  the
earlier  years  of  childhood,  probably
in  response  to  upper  respiratory
tract  infection.  Maximum  bulk  is
obtained  at  the  age  of  about  6
years, thereafter, some regression in
size  is  to  be  expected,  and  in  old
age it atrophies

The tympanic membrane separates the EAM
from the middle ear. It is thin, nearly oval
disk, forming an angle of about 55 with
the floor of the meatus. It has a pearly
grey colour with a triangular bright area;
the cone of light; extending from the
centre (umbo) downwards and forwards.

Waldeyer's ring is characterized by:
1. Sub-epithelial lymphoid tissue.
2. Lack a definite capsule.
3. They have efferent lymph vessels,

but no afferent vessels.

4. Function as one unit: when a

member of it is removed, the
others

parts

undergo

compensatory hypertrophy.

5. The exact function is unknown, but it's

thought that it has a protective function
by:

a. Formation of lymphocytes.

b. Secretion of antibodies, mainly lgA.

c. Localization of infection entering the body

by initial contact with incoming
organisms.

Are two masses of lymphoid tissue situated

on  each  side  of  the  oropharynx.  The
medial  surface  is  exposed  in  the  pharynx
and  is  pitted  by  a  number  of  crypts.  The
tonsil  is  related  anteriorly  and  posteriorly
to

the

palatoglossus

and

palatopharyngeus muscles respectively.

Laterally the tonsil is enclosed by a dense

fibrous  capsule  separating  the  tonsil  from
the  superior  constrictor  muscle  (tonsillar
bed).  This  capsule  provide  a  convenient
plane  of  separation  of  the  tonsil  during
tonsillectomy.

Palatine tonsil

The tonsils lie between the

Two pillars

1. The main supply is the tonsillar branch of

the facial artery.

2. Lingual artery.
3. Ascending pharyngeal artery.
4. Greater palatine artery.
The venous drainage is to the

paratonsillar vein which drains to the
pharyngeal plexus. This plexus drains into
the internal jugular and anterior facial
veins.

Deep cervical chain of lymph nodes.

Sensory Nerve Supply

Nasopharynx: Maxillary nerve

Oropharyn x: Glossopharyngeal nerve

Laryngopharynx

: I

nternal laryngeal branch of the

vagus nerve

Motor Nerve Supply

All the muscles of pharynx, except the

stylopharyngeus,  supplied  by  the
pharyngeal plexus. The plexus is formed
by  the  pharyngeal  branches  of  the  IX
and  X  nerves  together  with  the
sympathetic  fibers  from  the  superior
cervical ganglion.

The stylopharyngeus is supplied by the

glossopharyngeal nerve

This space lies behind the pharynx and

extends from the base of the skull to the
superior mediastinum.

The anterior wall is formed by the posterior

pharyngeal wall and it's covering
buccopharyngeal fascia. The posterior wall
is formed by the cervical vertebrae and
their covering muscles and fascia.

Pharyngeal Wall

Contents:

retropharyngeal lymphnodes of

Rouviere. These are paired lymphnodes
separated from one another by a median
partition.

They

usually

disappear

spontaneously during the 3rd or 4th year
of life.

Retro and parapharyngeal spaces

This potential space which resembles an

inverted pyramid lies lateral to the
pharynx and connects posteriorly with the
retropharyngeal space. It extends from
the base of the skull to the hyoid bone.

It's bounded medially by the superior

constrictor muscle. Laterally lies the
medial pterygoid muscle, the mandible
and the parotid gland. It's posterior wall is
the prevertebral muscles and fascia.