anatomy and physiology of pharynx ( oro and naso and pharyngeal)

ANATOMY OF PHARYNX
& ITS CONGENITAL
ANOMALIES
Presenters – Agraja & Ajith

Table of contents
01 02
Anatomy of pharynx
Congenital anomalies

❑The pharynx is a cone-shaped
fibromuscular tube forming the upper
part of the air and food passages.
❑12-14 cm in length.
❑Extends from the base of the skull to
the lower border of the cricoid
cartilage, where it becomes continuous
with the oesophagus.
❑The width of the pharynx is 3.5 cm at
its base and this narrows to 1.5 cm at
the pharyngo-oesophageal junction,
which is the narrowest part of digestive
tract apart from the appendix

Pharyngeal Spaces
There are two potential spaces in
relation to the pharynx where
abscesses can form:
1. Retropharyngeal space, situated
behind the pharynx and extending
from the base of skull to the
bifurcation of trachea.
2. Para pharyngeal space, situated
on the side of pharynx. It contains
carotid vessels, jugular vein, last
four cranial nerves and cervical
sympathetic chain .

STRUCTURE OF
PHARYNGEAL WALL
From within outwards it consists of
four layers:
1. Mucous membrane
2. Pharyngeal aponeurosis
(pharyngobasilar fascia)
3. Muscular coat
4. Buccopharyngeal fascia

(a)Mucous Membrane
• Lines the pharyngeal cavity and is
continuous with the mucous membrane of
eustachian tubes, nasal cavities, mouth,
larynx and oesophagus.
• Ciliated columnar epithelium in the
nasopharynx and stratified squamous
elsewhere.
• There are numerous mucous glands
scattered in it.

• Fibrous layer that lines the muscular
coat and is particularly thick near the
base of the skull but is thin and
indistinct inferiorly.
• Fills up the gap left in the muscular
coat near the base of the skull.
(b)Pharyngeal Aponeurosis
(Pharyngobasilar Fascia)

(c)Muscular coat
It consists of two layers of muscles with
three muscles in each layer:
I. External layer: It contains superior,
middle and inferior constrictor
muscles.
II. Internal layer: It contains
stylopharyngeus, salpingopharyngeus
and palatopharyngeus muscles.

(d) Buccopharyngeal fascia
• It covers the outer surface of the
constrictor muscles.
• In the upper part, it is also
prolonged forwards to cover the
buccinator muscles.
•Above the upper border of the
superior constrictor, it blends
with pharyngeal aponeurosis.

KILLIAN’S DEHISCENCE
• Inferior constrictor muscle has two parts:
thyropharyngeus with oblique fibres and
cricopharyngeus with transverse fibres.
•Between these two parts exists a potential gap
called Killian’s dehiscence.
• It is also called “gateway of tears” as
perforation can occur at this site during
oesophagoscopy.
•This is also the site for herniation of
pharyngeal mucosa in cases of pharyngeal
pouch.

WALDEYER’S RING
Scattered throughout the pharynx in its sub-
epithelial layer in the lymphoid tissue which
is aggregated at places to form masses,
collectively called Waldeyer’s ring. The
masses are:
1. Nasopharyngeal tonsil or the adenoids
2. Palatine tonsils or simply the tonsils
3. Lingual tonsil
4. Tubal tonsils (in fossa of Rosenmüller)
5. Lateral pharyngeal bands
6. Nodules (in posterior pharyngeal wall

●The cavity of the
pharynx can be divided
into:
1.Nasopharynx
●2.Oropharynx
●3.Laryngopharynx

NASOPHARYNX
Also called epipharynx.
It lies behind the nasal cavities and extends from the
base of skull to the soft palate or the level of the
horizontal plane passing through the hard palate.
Boundaries:
Roof of the nasopharynx is formed by basisphenoid
and basiocciput.
Posterior wall is formed by arch of the atlas
vertebra covered by prevertebral muscles and fascia.
Both the roof and the posterior wall imperceptibly
merge with each other.

NASOPHARYNX (conti…)
●Floor is formed by the soft palate anteriorly
but is deficient posteriorly. It is through this
space, the nasopharyngeal isthmus, that
the nasopharynx communicates with the
oropharynx.
●Anterior wall is formed by posterior nasal
apertures or choanae, separated from each
other by the posterior border of the nasal
septum. Posterior ends of nasal turbinates
and meatuses are seen in this wall.

Lateral wall. Each lateral wall presents the
pharyngeal opening of eustachian tube situated 1.25
cm behind the posterior end of inferior turbinate. It
is bounded above and behind by an elevation called
torus tubarius raised by the cartilage of the tube.
Above and behind the tubal elevation is a recess
called fossa of Rosenmüller, which is the
commonest site for origin of carcino-
ma (Figure 47.5). A ridge extends from the lower
end of torus tubarius to the lateral pharyngeal wall
and is called salpingopharyngeal fold It is raised by
the corresponding muscle.

NASOPHARYNGEAL TONSIL
(ADENOIDS)
• It is a sub-epithelial collection of
lymphoid tissue at the junction of the
roof and posterior wall of the
nasopharynx and causes the
overlying mucous membrane to be
thrown into radiating folds.
• It increases in size up to the age of 6
years and then gradually atrophies.

NASOPHARYNGEAL BURSA
• It is an epithelial-lined median recess found
within the adenoid mass and extends from
pharyngeal mucosa to the periosteum of the
basiocciput.
• It represents the attachment of notochord to the
pharyngeal endoderm during embryonic life.
• When infected, it may be the cause of persistent
postnasal discharge or crusting.
• Sometimes an abscess can form in the bursa
(Thornwaldt’s disease).

RATHKE’S POUCH
• It is represented clinically by a
dimple above the adenoids and is
reminiscent of the buccal mucosal
invagination, to form the anterior
lobe of pituitary.
• A craniopharyngioma may arise
from it.

TUBAL TONSIL
It is a collection of sub-epithelial
lymphoid tissue situated at the tubal
elevation.
• It is continuous with adenoid tissue
and forms a part of the Waldeyer’s
ring.
• When enlarged due to infection, it
causes eustachian tube occlusion.

SINUS OF MORGAGNI
• It is a space between the base of the skull and
upper free border of superior constrictor
muscle.
• Through it enters
(i) the eustachian tube,
(ii) the levator veli palatini,
(iii) tensor veli palatini
(iv) ascending palatine artery—a branch of the
facial artery.

PASSAVANT’S RIDGE
• It is a mucosal ridge raised by fibers of
palatopharyngeus.
• It encircles the posterior and lateral walls
of nasopharyngeal isthmus.
• Soft palate, during its contraction, makes
firm contact with this ridge to cut off
nasopharynx from the oropharynx during
the deglutition or speech.

EPITHELIAL LINING OF NASOPHARYNX
• Functionally, nasopharynx is the
posterior extension of nasal
cavity.
• It is lined by pseudostratified
ciliated columnar epithelium.

Lymphatic Drainage of Nasopharynx
Lymphatics of the nasopharynx, including those of the
adenoids and pharyngeal end of eustachian tube, drain
into upper deep cervical jugular nodes either
directly or indirectly through retropharyngeal and
parapharyngeal lymph nodes. They also drain into
spinal accessory chain of nodes in the posterior
triangle of the neck. Lymphatics of the nasopharynx
may also cross midline to drain into contralateral
lymph nodes.

FUNCTIONS OF NASOPHARYNX
• Acts as a conduit for air.
• Through the eustachian tube, it ventilates the middle ear and
equalizes air pressure on both sides of tympanic membrane.
• Elevation of the soft palate against the posterior pharyngeal
wall and the Passavant’s ridge helps to cut off the
nasopharynx from the oropharynx.
• Acts as a resonating chamber during voice production.
• Acts as a drainage channel for the mucus secreted by nasal
and nasopharyngeal glands.

OROPHARYNX
• Oropharynx extends from the plane of hard
palate above to the plane of hyoid bone
below.
• It lies opposite the oral cavity with which it
communicates through oropharyngeal
isthmus.
• The latter is bounded above, by the soft
palate; below, by the upper surface of
tongue; and on either side, by palatoglossal
arch (anterior pillar).

BOUNDARIES OF OROPHARYNX
1. Posterior wall
Posterior pharyngeal wall & lies opposite the second and
upper part of the third cervical vertebrae.
2. Anterior wall
It is deficient, where oropharynx communicates with the
oral cavity, but below it presents:
(a) Base of tongue, posterior to circumvallate papillae.
(b) Lingual tonsils, one on either side, situated in the base
of tongue.
(c) Valleculae: They are cup-shaped depressions lying
between the base of tongue and anterior surface of
epiglottis. Each is bounded medially by the median
glossoepiglottic fold and laterally by pharyngoepiglottic
fold

3. Lateral wall.
•It presents:
(a) Palatine (faucial) tonsil
(b) Anterior pillar (palatoglossal
arch) formed by the palatoglossus
muscle.
(c)Posterior pillar (palatopharyngeal
arch) formed by the
palatopharyngeus muscle.

3. Lateral wall.
Both anterior and posterior pillars
diverge from the soft palate and
enclose a triangular depression called
tonsillar fossa in which is situated
the palatine tonsil.
Boundary between oropharynx above
and the hypopharynx below is
formed by upper border of epiglottis
and the pharyngoepiglottic folds.

Lymphatic Drainage of Oropharynx
Lymphatics from the oropharynx drain into
upper jugular chain particularly the
jugulodigastric (tonsillar) node.
The soft palate, lateral and posterior
pharyngeal walls and the base of tongue also
drain into retropharyngeal and
parapharyngeal nodes and from there to the
jugulodigastric and posterior cervical group.
The base of tongue may drain bilaterally.

FUNCTIONS OF OROPHARYNX
1. It serves as a conduit for passage of air and food.
2. Helps in the pharyngeal phase of deglutition.
3. Forms part of vocal tract for certain speech sounds.
4. Helps in appreciation of the taste. Taste buds are present in the base of
tongue, soft palate, anterior pillars and posterior pharyngeal wall.
5. Provides local defense and immunity against harmful intruders into the air
and food passages.

HYPOPHARYNX (LARYNGOPHARYNX)
The lowest part of the pharynx lies behind and partly
on the sides of the larynx.
•Superior limit: Plane passing from the body of
hyoid bone to the posterior pharyngeal wall
•Inferior limit: Lower border of cricoid cartilage
where hypopharynx becomes continuous with
esophagus.
•Clinically, it is subdivided into three regions—the
pyriform sinus, post cricoid region and the
posterior pharyngeal wall.

Pharynx opened from behind showing structures related
to nasopharynx, oropharynx and laryngopharynx

Pyriform sinus (fossa)
• It lies on either side of the
larynx and extends from
pharyngoepiglottic fold to
the upper end of
esophagus.
• It is bounded laterally by
the thyrohyoid membrane
and the thyroid cartilage
and medially by the
aryepiglottic fold,
posterolateral surfaces of
arytenoid and cricoid
cartilages .
• It forms the lateral channel
for food.

Post cricoid region
• It is the part of the anterior wall of
laryngopharynx between the upper and lower
borders of cricoid lamina.
• It is a common site for carcinoma in females
suffering from Plummer–Vinson syndrome.

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FUNCTIONS OF HYPOPHARYNX
• Laryngopharynx, like oropharynx, is a common pathway for
air and food, provides a vocal tract for resonance of certain
speech sounds and helps in deglutition.
• There is coordination between contraction of pharyngeal
muscles and relaxation of cricopharyngeal sphincter at the upper
end of esophagus.

3 Pairs of Pharyngeal Constrictor
Muscles

• The arteries supplying the pharynx are almost the same
as those supplying the tonsil. These are as follows:
1. Ascending pharyngeal branch of the external carotid
artery.
2. Ascending palatine and tonsillar branches of the facial
artery.
3. Dorsal lingual branches of the lingual artery.
4. The greater palatine, pharyngeal and pterygoid
branches of the maxillary artery.
• The veins form a plexus on the posterolateral aspect of
the pharynx. The plexus receives blood from the
pharynx, the soft palate and the prevertebral region. It
drains into the internal jugular and facial veins.
BLOOD SUPPLY OF PHARYNX

The Relationship of the Pharynx to the Vertebral Column
• The pharynx is suspended from the base of the skull, is
surprisingly free from the cervical column.
• This is reasonable, since the pharynx has no muscular
attachments to the vertebrae.
• The mechanism responsible for velopharyngeal closure plays an
extremely important role in speech production, and we ought to
become familiar with it.

NASOPHARYNGEAL ANOMALIES
The nasopharynx is the embryonic intersection of the
neural axis, alimentary, and respiratory tracts and is
subject to a variety of congenital malformations.
1.Cystic lesions
• Squamous-lined cysts in the midline of the
nasopharynx are thought to arise from rests of Rathke
pouch.
• Thornwaldt cysts — Thornwaldt cysts are midline
nasopharyngeal cysts that are thought to arise from
obstruction at the Thornwaldt bursa, at the junction of
the remnants of the notochord and the pharyngeal
ectoderm.

• First branchial pouch cysts:
The first branchial pouch arises in the pharynx and
extends laterally and cephalad to contact the first
branchial cleft, forming the Eustachian tube. First
branchial pouch cysts, resulting from errors in
embryogenesis, may present in the lateral wall of the
nasopharynx.
• Teratomas:
Nasopharyngeal teratomas are principally solid
masses composed of tissues derived from embryonic
ectoderm, mesoderm, and endoderm. They can be
benign or malignant. Teratomas that protrude from
the mouth may be diagnosed on prenatal ultrasound
and can cause upper airway obstruction in the
neonate.

• Heterotopic brain:
Heterotopic brain can be located in the nasopharynx, even in the absence of an
encephalocele. Surgical removal, usually by a trans palatal route, has been
advocated for diagnosis and relief of upper airway obstruction.
• Ectopic pituitary:
Rarely, functional pituitary tissue may present in the nasopharynx associated
with failed closure of the craniopharyngeal canal. A small sella turcica and
persistent craniopharyngeal canal can be demonstrated on T1-weighted MRI.
MRI usually provides sufficient information to make the diagnosis, and biopsy
generally should be avoided in this setting.

PHARYNGEALANOMALIES
• Second branchial pouch: Second branchial cleft and pouch anomalies
are the most common branchial defects. The second branchial pouch
originates in the oropharynx. Second branchial pouch anomalies typically
present as masses in the oropharynx, which is the site of the palatine
tonsils and the embryologic origin of the second branchial pouch.
• Cysts, sinuses, and fistulae of the second branchial cleft often can be
tracked to the inferior tonsillar pole during resection. Pharyngeal and
pharyngolaryngeal bands are a rare cause of obstruction of the upper
aerodigestive tract. The associated lack of tonsillar and adenoid tissue in
patients with these anomalies suggests that the anomalies may be caused
by failed formation of the second branchial arch.

• Third and fourth branchial arch : The hypopharynx is the
source for the third and fourth branchial pouches each arising in
the pyriform sinus. Cysts of third or fourth branchial origin
present as recurrent abscesses in the neck or simulate suppurative
thyroiditis. Preoperative barium esophagography or direct
laryngoscopy may reveal an outpouching of the pyriform apex.
Failure to follow the tract all the way to the pyriform sinus may
result in recurrent cervical infection.

• In the newborn, adenoidal tissue is very sparse but by 3 month of
age a half centimeter or so of tissue thickness is usually present.
• Thereafter, it increases even more, but there is considerable
variability. If adenoidal tissue is not visualized after 6 months of
age, the possibility of hypogammaglobulinemia should be
considered.
• In some patients, the adenoidal tissue may extend into the
retropharyngeal space, Such extensions may be nodular or smooth
and may at first suggest a retropharyngeal mass or abscess.

References:
1. Dhingra, P. L. (2013). Diseases of Ear, Nose and Throat. Chennai, Elsevier. •
2. Hazarika, P., Nayak, D. R., Balakrishnan, R. (2010). Textbook of Ear, Nose, Throat and Head and Neck Surgery. New
Delhi, CBS Publishers & Distributors.
3. BD Chaurasia’s Human Anatomy, Regional and Applied Dissection and Clinical Volume 3 & Volume 4. Eighth
Edition. CBS Publishers & Distributors.
4. Willard R. Zemlin. Speech and Hearing Science, Anatomy & Physiology. Third Edition.Englewood Cliffs, New
Jersey.
5. Ann W.Kummer. Cleft Palate and Craniofacial Conditions. A Comprehensive Guide to Clinical Management. Fourth
Edition. Jones & Barlett Learning.
6. Congenital anomalies of the jaw, mouth, oral cavity, and pharynx (medilib.ir)

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