Anatomy of pharynx

1. Anatomy of
Pharynx
1
Kasturi Ramasamy

2.  Conical fibromuscular tube –
upper part of the air & food
passages
 Location:
 Behind the nasal cavity, oral
cavity and larynx
 Extend from the base of the
skull to the inferior border of
cricoid cartilage (anteriorly) &
the inferior border of C6
vertebra (posteriorly)
 Dimensions:
 12-14cm long
 Width :
 3.5 cm (at its base)
 1.5 cm (pharyngo-oesophageal
junction –narrowest part)
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3. 3

4. Superior
Base of the skull
• Part of body of
sphenoid
• Basilar part of
occipital bone
Anterior (Incomplete)
Nasal cavity
Oral cavity
Larynx
Posterior
Retropharyngeal
space (between the
buccopharyngeal &
prevertebral fascia)
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Inferior
Continuous with oesophagus
(at level of C6 & lower border of
circoid cartilage

5. 5

6. Structure of pharyngeal wall
PHARYNGEAL APONEURESIS
(Pharyngobasilar fascia)
• Fibrous layer which lines muscular coat
• Thick (base of skull) & thin ( inferiorly)
MUCOUS MEMBRANE
• Lines pharyngeal cavity &
continuous with mucous membrane
Eustachian tubes, nasal cavities,
mouth, larynx & esophagus
• Stratified squamous except
nasopharynx (ciliated columnar)
• Numerous mucous glandsMUSCULAR COAT
• External layer : superior, middle,
inferior constrictor muscle
• Internal layer : stylopharyngeus,
salphingopharyngeus,
palatopharyngeus muscle
BUCCOPHARYNGEAL FASCIA
• Outer surface of constrictor muscle &
buccinator muscle
• Upper border of superior constrictor: Blend
with pharyngeal aponeurosis
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7. External layer of muscular coat
Constrictor muscles of pharynx
 Generally:
 Origins are situated
anteriorly
 Fibers pass through anterior
& posterior wall of pharynx
 All 3 muscles meet in
midline (in a fibrous raphe)
 Arrangement:
 Inferior constrictor overlaps
the middle constrictor
 Middle constrictor overlaps
the superior constrictor
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8. Superior constrictor muscle
Origin (from above to downwards)
• Pterygoid hamulus
• Pterygomandibular raphe
• Medial surface of mandible at posterior end of mylohyoid line
(near the attachment of pterygomandibular raphe)
• Side of the posterior part of the tongue
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9. Middle constrictor muscle
Origin
• Lower part of stylohyoid ligament
• Lesser cornu of hyoid bone
• Upper border of greater cornu of hyoid bone
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10. Inferior constrictor muscle
1. Thyropharnygeus
• Arise from thyroid cartilage
–oblique line and inferior tubercle
of thyroid cartilage
• A tendinous band that crossed
the cricothyroid muscle & is
attached above to the inferior
tubercle of thyroid cartilage
2. Cricopharyngeus
• Cricoid cartilage behind the origin
of cricothyroid muscle
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11. Internal layer of muscular coat [longitudinal muscles]
1. Stylopharyngeus
From styloid process,
• passes through the gap between superior & middle
constrictor
• Run downward to the inner surface of middle and
inferior constrictor
Stylopharyngeus
muscle
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12. 2. Palatopharyngeus
• Descends from the sides of palate
• Runs longitudinally on the internal aspect of 3
constrictors
Palatopharyngeus
muscle
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13. 3. Salpingopharyngeus
• Descends from the auditory tube
• Merges with the palatopharyngeus muscle
Salpingopharyngeus
muscle
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16. Killian’s Dehiscence
 Potential gap between thyropharyngeus with oblique fibers and
the cricopharyngeus with transverse fibers
 “Gateway of tears”  Perforation can occur at this site during oesophagoscopy
 Site for herniation of pharyngeal mucosa in condition of pharyngeal pouch
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17. Waldeyer’s Ring *inner
• Several aggregations of lymphoid tissue
near the relation of oropharyngeal isthmus
• Composed of:
1. Right & left palatine tonsil (tonsil only)
2. Pharyngeal tonsil (posteriorly & above)
3. Tubal tonsil (laterally & above) –in fossa Rosenmuller
4. Lingual tonsil (posterior part of the dorsum of the
tongue)
5. Palatine tonsils
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18. Pharyngeal Spaces
1. Retropharyngeal space
• Situated behind the pharynx & extending from the
base of skull to the bifurcation of trachea
• Divided into 2 lateral compartments [spaces of Gillette]
by a fibrous raphe
• Has retropharyngeal nodes –disappear at 3-4
years
• Infection can pass down behind the oesophagus into
the mediastinum
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19. 2. Parapharyngeal space
• Situated on the side of pharynx
• Contains carotid vessels, jugular vein, last
four cranial nerves & cervical sympathetic
chain
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20. Parts of pharynx
Laryngopharynx
• Plane of hyoid bone  lower border of
cricoid cartilage
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Nasopharynx
• Base of skull  nasopharyngeal isthmus
Oropharynx
• Nasopharyngeal isthmus  plane of hyoid
bone

21. Parts of pharynx
1. Nasopharynx
Floor
• Soft palate anteriorly &
is deficient posteriorly
• Oropharynx via
nasopharyngeal
isthmus
Anterior
Nasal cavity via posterior nasal
apertures (choanae)
Lateral
Pharyngeal openings of the eustachian tube
In contact with anterior part of middle ear cavity (opens
at the level of inferior nasal conchae)
Roof
Basisphenoid & Basiocciput
Posterior
Prevertebral muscles &
fascia
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• Uppermost part of
pharynx (epipharynx)
• Lies behind the
nasal cavity
• Base of skull  Soft
palate/Level of the
horizontal plane
passing thru the hard
palate
• Lined by respiratory
epithelium
(pseudostratified
ciliated columnar
epithelium)
• Rigid and non-
collapsible wall

22. Lateral wall of nasopharynx
Pharyngobasillar fascia + Posterior median pharyngeal ligament/raphe
1.25 cm behind the
posterior end of
inferior turbinate
Bounded above
and behind by tubal
elevation (torus
tubarius)
Above and behind
the tubal elevation
is a recess called
fossa of
Rossenmuller
–Lies above the
upper edge of
superior constrictor
muscle & common
site for origin of
carcinoma
• Vertical fold of
mucous
membrane that
is raised by the
salpingopharyn
geus muscle
• Running
downwards from
the posterior
margin of tubal
elevation,
gradually fading
on the side wall
of pharynx
Extend from
anterosuperior
angle of tubal
elevation to soft
palate22

23. Posterior rhinoscopy image
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24. Pharyngeal/ Nasopharyngeal
Tonsil/ Adenoids
Sub-epithelial collection of lymphoid tissue at
the junction of roof and posterior wall of
nasopharynx –increases in size up to 6 years
& gradually atrophies.
Tubal tonsil
Collection of sub-epithelial lymphoid tissue
situated at the tubal elevation.
Rathke’s pouch
Dimple above adenoids reminiscent of buccal mucosal
invagination, to form anterior lobe of pituitary.
(*craniopharyngioma may arise from it)
Nasopharyngeal Bursa
• Epithelial lined median recess within adenoid mass &
extends from pharyngeal mucosa to the periosteum of the
basiocciput
• Attachment of notochord to the pharyngeal endoderm
during embryonic life (*abscess –Thornwaldt’s disease)24

25. Sinus of Morgagni
• Space between skull and
upper free border of superior
constrictor muscle.
• Structures passing through this
gap:
 Levator veli palatini
 Ascending palatine artery
 Tensor veli palatini
 Eustachian tube
Passavant’s Ridge
• Mucosal ridge raised by fibres of
palatopharyngeus
• Encircles posterior and lateral walls of
nasopharyngeal isthmus
• Soft palate, during its contraction makes
firm contact with this ridge to cut off
nasopharynx from oropharynx during
deglutition or speech
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26. Lymphatic drainage
• Upper deep cervical nodes through:
 Retropharyngeal nodes
 Parapharyngeal nodes
• Spinal accessory chain of nodes in the posterior triangle of the
neck
Functions
1. Acts as a conduit for air; nose and
larynx.
2. Ventilates middle ear through
eustachian tube and equalises air
pressure on both sides of TM.
3. Cuts off nasopharynx from
oropharynx with the help of
Passavant’s ridge.
4. Acts as a resonating chamber for
voice production
5. Acts as a drainage channel for
mucus secreted by nasal and
nasopharyngeal glands26

27. Parts of pharynx
2. Oropharynx
Middle part of
the pharynx
behind oral
cavity
Communicates
with:
• Nasopharynx
through
nasopharyngeal
(pharyngeal)
isthmus
• Oral cavity through
the oropharyngeal
isthmus (isthmus of
fauces)
• Laryngopharynx at
the level of upper
border of epiglottis
Lateral wall -Anterior pillar
Palatoglossal arch Lateral wall -
Posterior pillar
Palatopharyngeal arch
Posterior wall
Retropharyngeal space
Opposite to C2 and upper C3 vertebrae
Anterior wall
• Deficient above (communicates
with oral cavity)
• Below:
1. Base of the tongue –posterior
to circumvallate papilla
2. Lingual tonsil
3. Valleculae –cup shaped
depressions lying between the
base of the tongue & anterior
surface of epiglottis
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“Isthmus of fauces = limit between the mouth cavity proper with the pharynx
marked by constricted aperture  Palatopharyngeal and palatoglossal arches”

28. Anterior wall of oropharynx
• Deficient above
(communicates with oral
cavity)
• Below:
1. Base of the tongue –
posterior to circumvallate
papilla
2. Lingual tonsil
3. Valleculae –cup shaped
depressions lying
between the base of the
tongue & anterior surface
of epiglottis
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30. Lateral wall of oropharynx
Pharyngeal wall
• Forms the lateral
boundaries of tonsillar
fossa
• Composed of (from within
to outward):
1. Pharyngobasilar fascia
2. Superior constrictor &
palatopharyngeus
muscles
3. Buccopharyngeal fascia
4. Styloglossus muscle &
glossopharyngeal nerve
(lower part)
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31. Tonsillar fossa
A triangular
depression b/w the
anterior and the
posterior pillars,
contain palatine tonsils
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32. Lymphatic drainage
• Upper jugular chain: jugulo-digastric nodes (tonsillar)
• Soft palate, lateral & posterior pharyngeal walls & base of
the tongue Retropharyngeal and parapharyngeal
nodes  jugulo-digastric & posterior cervical group
Functions
1. Conduit passage for air and food
2. Helps in pharyngeal phase of
deglutition
3. Forms part of vocal tract for speech
sounds
4. Helps in appreciation of taste (taste
buds)
5. Provide local immunity and defense
against harmful intruders
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33. Parts of pharynx
3. Laryngopharynx (Hypopharynx)
• Lowest part
• Situated behind the larynx
• Extend from upper border of epiglottis to lower
border of cricoid cartilage
Mucosa membrane covering
the lamina of cricoid cartilage
Anterior (Post-cricoid region)
• Laryngeal inlet
• Posterior surface of cricoid and arytenoid cartilage
*common site for carcinoma in females with Plummer Vinson
syndrome
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34. 34
Lateral wall
[Piriform fossa]
• On each side of laryngeal inlet
• Pharyngoepiglottic fold  upper end
of oesophagus
• Boundaries:
 Medially: aryepiglottic fold,
posterolateral surfaces of
aryteniud & circoid
cartilages
 Laterally: thyroid cartilage &
thyrohyoid membrane
 Covered by mucous membrane.
Beneath the membrane is
internal laryngeal nerve
• Smuggler’s fossa -Foreign bodies
may get lodged here
• Removal of foreign body from the
piriform fossa may damage the nerve
anesthesia to the supraglottic part
Posterior
• Level of hyoid bone to the
level of cricoarytenoid joint

35. Lymphatic drainage
• Pyriform sinus  upper jugular chain
• Rich lymphatics  high frequency of nodal metastasis
in carcinoma of this region
• Post cricoid  parapharyngeal LN / nodes of
supraclavicular and paratracheal chain
• Post wall parapharyngeal LN or lateral pharyngeal LN
 deep cervical LN
Functions
1. Common pathway for air and food
2. Help in deglutition
3. Provides a vocal tract for resonance of
certain speech sounds
4. Co-ordination between the contraction
of pharyngeal ms and relaxation of
cricopharyngeal sphincter at the upper
end of oesophagus
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36. Autonomic innervation
Parasympathetic
(secretomotor)
1.Greater petrosal nerve (branch of
facial nerve)
2.Lesser palatine branches of
pterygopalatine ganglion
Sensory innervation
Afferent fibers travel through:
1.Glossopharyngeal nerve (mostly)
2.Vagus nerve (partly)
3.Maxillary nerve through pterygopalatine ganglion (nasopharynx
only)
4.Lesser palatine and glossopharyngeal nerve (soft palate & tonsil)
Motor innervation
• All muscles of pharynx are supplied by the cranial accesory nerve through branches of
vagus except stylopharyngeus muscle[ pharyngeal branches of glossopharyngeal nerve]
• Inferior constrictor muscle has additional supply from the external and recurrent laryngeal nerves
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Generally, all the nerves supplying the pharynx form a plexus (pharyngeal plexus) which chiefly
lies on the middle constrictor muscle:
1.Pharyngeal branch of vagus carrying cranial accesory nerve fibers
2.Pharyngeal branch of glossopharyngeal nerve
3.Pharyngeal branch of the superior sympathetic ganglion
Fibers from pharyngeal plexus also supplies the muscles of soft palate except tensor veli palatini
(by Mandibular nerve)

37. Blood supply of pharynx
 Arterial supply:
1. Ascending pharyngeal branch of
ECA
2. Ascending palatine branch of Facial
artery
3. Tonsillar branch of Facial artery
4. Dorsal lingual branch of lingual artery
5. Greater palatine, pharyngeal branch &
pterygoid branch of maxillary artery
 Veins :
 Form plexus at the posterolateral aspect
of pharynx, soft palate & prevertebral
region  drains into facial and IJV
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38. References
 Dhingra’s Diseases of ENT 6th pg. 238-242
THANK YOU
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