Pharynx is a conical fibromuscular tube forming upper
part of air and food passages.
Structure of Pharyngeal wall.
From outwards:4 layers
Plane of hard palate above to the plane of hyoid
Lies opposite to the oral cavity with which it
communicates thro’ oropharyngeal istmus.
Boundries of istmus:
Below:upper surface of tongue.
Either side:palatopharyngeal arches.
Posterior wall:related to retropharyngeal spaces and lies
opposite to the 2nd
and upper part of 3rd
Anterior wall:deficient above where oropharynx
communicates with oral cavity but below
(a)Base of tongue:posterier to circumvallate papillae
(b)Lingual tonsils:one on either side situated on base of
(c) Valleculae:cup shaped depression lying b/w the base of
the tongue and anterior surface of epiglottis.
Each is bounded medially by the median
glossopharyngeal fold and laterally by
pharyngoepiglottic fold.These are seat of retention cyst.
(b)Anterior pillar formed by palatoglossus muscle.
(c)Postreior pillar formed by palatopharyngeus muscle.
Both the anterior & posterior pillar diverge from soft
palate & encloses triangular depression called Tonsillar
fossa where tonsil is situated.
Oropharynx Jugulo digasic node.
Soft palate,lateral & posterior pharyngeal walls
and base of the tongue
retro and para pharyngeal nodes
jugulodigastic and posterior cervical groups.
Base of the tongue bilaterally
As a conduit for passage of food and air.
Helps in the pharyngeal phase of deglutition.
Forms part of vocal tract for certain speech
Helps in appreciation of taste:taste bubs
present on the base of tongue,soft
palate,anterior pillars &post pharyngeal walls.
Provides local defence & immunity.
Two in number.
Each is ovoid mass of lymphoid tissue situated in
the laterel wall of oropharynx b/w the anterior &
Actual size is bigger than that appears from the
surface as tonsil extends upwards into the soft
palate,downwards into the base of the tongue
&anteriorly into the palatopharyngeal arch.
Tonsils have: Two surfaces:medial & lateral.
Two poles:upper and lower.
Medial surface:covered by st.sq.non keratinised epithelium
which dips into the surface of tonsils as crypts.
Openings of 12 to 15 crypts can be seen on the medil
surface of tonsils.
One of them in the upper part of the tonsil is very large &
deep & called as Crypta Magna/Intra tonsillar cleft which
represents the ventral part of 2nd
From the main crypts arise secondary crypts within the
substance of tonsils.
Crypts may be filled with cheesy material consisting of epith
cells,bacteria & food debris which can be expressed by the
pressure over anterior pillar.
Lateral surface:presents a well defined fibrous
B/w the tonsil & the bed of the tonsil is the areolar
tissue which makes it easy to dissect the tonsil in
the plane during tonsillectomy.
Also the site for collection of pus in peritonsillar
Some fibres of palatoglossus &palatophartngeal
muscles are attached to the capsule of the tonsil.
Upper pole:extends into the softpalate.
Its medial surface covered by semilunar fold extending
b/w anterior & posterior pillars & enclosing a potential
space called supratonsillar fossa.
Lower pole:attached to the tongue.A triangular fold of
mucous membrane extends from anterior pillar to
antero inferior part of tonsil & encloses a space called
anterior tonsillar space.
The tonsil seperated from the tongue by sulcus called
tonsillolingual sulcus which may a seat of carcinoma.
Bed of the tonsil:
Formed by superior constrictor & styloglossus muscle.
The glossopharyngeal nerve & styloid process if
enlarged may lie in relation to the lower part of tonsillar
fossa.so both these structures can be surgically
approached thro’ tonsil bed after tonsillectomy.
Outside the superior constrictor,tonsil is related to the
facial artery,submandibular salivary gland,posterior belly
of digastic muscle,medil pterygoid muscle & the angle of
Tonsillar branch of facial artery:Main artery.
Ascending pharyngeal artery from external carotid
Ascending palatine a branch of facial artery.
Dorsal lingual branches of lingual artery.
Descending palatine branch of maxillary artery.
Venous drainage:tonsillar vein:paratonsillar
vein:common facial vein:pharyngeal venous plexuses.
Lymphayics from tonsil Deep cervical nodes
particularly jugulodigastic nodes below the
angle of mandible.
Nerve supply:lesser palatine branches of
glossopharyngeal nerve provide sensory nerve
Protective role & act as sentinals at the portal
of air & food passages.
Crypts:increase the srface area for contact with
the foreign substances.
Tonsils are larger in childhood 7 gradually
dicrease in size by the time of puberty.
Removed when themselves become seat of