2.  Pharynx is a conical fibromuscular tube forming upper
part of air and food passages.
 Divisions:Nasopharynx
Oropharynx
Hypo/laryngopharynx.
 Structure of Pharyngeal wall.
 From outwards:4 layers
Mucous membrane
Pharyngeal aponeurosis
Muscular coat
Buccopharyngeal fascia.

4.  Extension:
 Plane of hard palate above to the plane of hyoid
bone below.
 Lies opposite to the oral cavity with which it
communicates thro’ oropharyngeal istmus.
 Boundries of istmus:
Above:soft palate
Below:upper surface of tongue.
Either side:palatopharyngeal arches.

5.  Posterior wall:related to retropharyngeal spaces and lies
opposite to the 2nd
and upper part of 3rd
cervical
vertebrae.
 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
the tongue.
(c) Valleculae:cup shaped depression lying b/w the base of
the tongue and anterior surface of epiglottis.

9.  Each is bounded medially by the median
glossopharyngeal fold and laterally by
pharyngoepiglottic fold.These are seat of retention cyst.
 Lateral wall:
(a)Palatine tonsil
(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.

10.  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

11.  As a conduit for passage of food and air.
 Helps in the pharyngeal phase of deglutition.
 Forms part of vocal tract for certain speech
sounds.
 Helps in appreciation of taste:taste bubs
present on the base of tongue,soft
palate,anterior pillars &post pharyngeal walls.
 Provides local defence & immunity.

12.  Two in number.
 Each is ovoid mass of lymphoid tissue situated in
the laterel wall of oropharynx b/w the anterior &
posterior pillars.
 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.

14.  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
pharyngeal pouch.
 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.

15.  Lateral surface:presents a well defined fibrous
capsule.
 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
abscess.
 Some fibres of palatoglossus &palatophartngeal
muscles are attached to the capsule of the tonsil.

16.  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.

17.  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
mandible.

18.  5 arteries:
 Tonsillar branch of facial artery:Main artery.
 Ascending pharyngeal artery from external carotid
artery.
 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.

20.  Lymphatic drainage:
Lymphayics from tonsil Deep cervical nodes
particularly jugulodigastic nodes below the
angle of mandible.
 Nerve supply:lesser palatine branches of
sphenopalatine ganglion(5th
CN) &
glossopharyngeal nerve provide sensory nerve
supply.

23.  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
infection.