Download Anatomy of oral cavity + pharynx

Anatomy of Oral
Cavity, Pharynx &
Oesophagus
Dr. Vishal Sharma
Oral Cavity
Parts of Oral Cavity
Floor of mouth
Lymphatic drainage
Intrinsic tongue muscles
Extrinsic tongue muscles
Coronal section of tongue
Actions of tongue muscles
Inferior Longitudinal: moves tip up & down
Superior Longitudinal: moves tip up & down
Transverse: narrows & lengthens tongue
Vertical: flattens & depresses tongue
Genioglossus: Prevents tongue from falling back
Styloglossus: Pulls tongue up & back
Palatoglossus: Pulls tongue back
Hyoglossus: Depresses tongue
Nerve Supply of Tongue
Sensory
Motor
Taste
Anterior 2/3
Posterior 1/3
Lingual
Glossopharyngeal
Hypoglossal ***
Chorda tympani
Glossopharyngeal
*** except palatoglossus which is supplied by
pharyngeal plexus
Nerve
Supply
of
Tongue
Papillae in tongue
Papillae in tongue
Lingual taste buds sit on lateral borders of
raised papillae. They are classified as:

Fungiform: at tip & sides of tongue

Circumvallate: just in front of terminal sulcus

Foliate: at posterior lateral margins of tongue

Filiform: centre of tongue, have no taste buds
Papillae in tongue
Tongue Map ?

Sweet = Sucrose

Salty = NaCl

Sour = HCl

Bitter = Quinine

Umami = Glutamate
Taste Bud
Taste Pathway
Pharynx
Divisions
Divisions
Lower Limit of
Nasopharynx Lower border of soft palate or
Junction b/w hard & soft palate
Oropharynx
Tip of epiglottis or
Body of hyoid bone or
Base of vallecula
Hypopharynx Lower border of cricoid or
Lower border of C6 vertebra
Anterior Relations
Nasopharynx
Nasopharyngeal isthmus
Nasopharyngeal Isthmus
Separates nasopharynx from oropharynx
Bounded anteriorly by soft palate & posteriorly
by mucosal ridge on nasopharyngeal wall called
Passavant’s ridge (due to palatopharyngeus)
Closure of this isthmus prevents nasal
regurgitation & nasal intonation
Parts of Oropharynx
Parts of Oropharynx
Oropharyngeal Isthmus
Oropharyngeal Isthmus
Separates oral cavity from oropharynx
Boundaries are:
Superior: Junction between hard & soft palate
Inferior: Circumvallate papillae
Lateral: Anterior tonsillar pillars (palatoglossus)
Waldeyer’s Tonsillar Ring
Waldeyer's tonsillar ring
Vertically oriented, sub-epithelial lymphoid
tissue ring located in pharynx, thought to
function as a barrier to infection in first few
years of life. Named after nineteenth century
German anatomist Heinrich Wilhelm Gottfried
von Waldeyer-Hartz.
Parts of Hypopharynx
Coronal section of Pharynx
Layers of Pharyngeal Wall

Mucosa: ciliated columnar in nasopharynx &
stratified squamous elsewhere

Pharyngo-basilar fascia

Longitudinal muscles: stylo-pharyngeus +
salpingo-pharyngeus + palato-pharyngeus

Constrictor muscles: superior + middle + inferior

Bucco-pharyngeal fascia
Muscles
Structures Passing
Between Skull Base &
Superior Constrictor
(Sinus of Morgagni)
Eustachian tube + Levator
palatini + Tensor palatini +
Ascending palatine artery
Between Superior &
Middle Constrictors
Glossopharyngeal nerve &
Stylopharyngeus muscle
Between Middle &
Inferior Constrictors
Internal Laryngeal nerve &
Superior Laryngeal artery
Below Inferior
Constrictor
Recurrent Laryngeal nerve
& Inferior Laryngeal artery
Nerve Supply

Nasopharynx: pterygo-palatine ganglion (V2)

Oropharynx: glossopharyngeal & vagus nv

Hypopharynx: Superior & recurrent laryngeal nv

All muscles by pharyngeal nerve plexus (vagus
nv carrying cranial part of accessory nv) except
stylopharyngeus (glossopharyngeal nv) &
cricopharyngeus (also by recurrent laryngeal)
Arterial Supply

Facial artery

Lingual artery

Ascending pharyngeal artery

Ascending palatine artery

Greater palatine artery

Artery of pterygoid canal

Superior laryngeal artery
Venous Drainage
Upper pharynx:

Pharyngeal venous plexus situated on middle
constrictor  pterygoid venous plexus &
internal jugular vein
Lower pharynx:

Inferior thyroid veins
Lymphatic Drainage

Nasopharynx: upper deep cervical + retropharyngeal + parapharyngeal +
posterior triangle

Oropharynx: upper deep cervical + retropharyngeal + parapharyngeal

Hypopharynx: deep cervical + parapharyngeal +
paratracheal + supraclavicular
Killian’s Dehiscence
Killian’s Dehiscence

Triangular weak area between thyropharyngeus
& cricopharyngeus part of inferior constrictor

Mucosa herniates through it to form hypopharyngeal pouch (Zenker’s diverticulum)

Perforation occurs here during forceful
oesophagoscopy (gateway of tears)
Oesophagus
Introduction

Also called gullet

23 to 25 cm long

Extends from crico-pharyngeal sphincter (C6
vertebra) to cardiac orifice of stomach (T11
vertebra)
Anterior Curvature
Follows anteroposterior curve of
vertebral column
through neck, thorax
(postr mediastinum)
& upper abdomen
Lateral curvatures
Starts in midline →
deviates to left at C7
→ returns to midline
at T5 → deviates to
left again at T7 to
reach gastric cardia
Natural Constrictions
Natural Constrictions
Site
Vertebral Level
Distance from
central incisor
Cricopharynx
C6
15 cm
Aortic arch
T4
25 cm
Lt main
bronchus
T5
28 cm
Oesophageal
hiatus
T 10
40 cm
Importance of constrictions

Common sites for lodgement of oesophageal
foreign bodies

Common sites for caustic stricture of
oesophagus
Blood Supply
Part
Arterial
Venous
Cervical
Inferior thyroid
Inferior thyroid
Thoracic
Descending
thoracic aorta,
Bronchial
Left gastric,
Inferior phrenic
Azygos,
Hemi-azygos
Abdominal
Left gastric,
Abdominal azygos
Oesophageal varices
Left gastric vein is a
site of portal-systemic
anastomosis. Portal
obstruction leads to
varicose veins in
lower oesophagus
Nerve Supply
Cervical: recurrent laryngeal nerve & cervical
sympathetic trunk
Thoracic: vagal trunks, oesophageal plexus & thoracic
sympathetic trunk
Abdominal: vagal trunks & thoracic sympathetic trunk
Esophageal pain mimics cardiac angina due to
common nerve supply
Lymphatic Drainage
deep cervical + posterior mediastinal + left
gastric lymph nodes
drain into coeliac lymph nodes
thoracic duct
Histology
Histology
Four coats from outside inwards:
1. Fibrous coat (adventitia)
2. Muscular coat (muscularis propria)
3. Submucous coat
4. Mucous coat
Detailed Histology
Mucous coat
1. Epithelium: non-keratinizing stratified sqamous
2. Lamina propria: loose areolar tissue with
lymphoid aggregates
3. Muscularis mucosae: produces local
movement of mucosa & helps in
drainage of gland secretions
Mucous coat
Pink, smooth, protective
oesophageal mucosa
leads to red, mamillated,
secretory gastric mucosa
across Z (zigzag) line at
38-40 cm from incisors.
Higher Z line seen in
Barret’s esophagus.
Z line in endoscopy
Barret’s esophagus
Submucous coat
Loose supporting areolar tissue contains:

Seromucous glands

Blood vessels

Lymphatic channels

Parasympathetic ganglia forming Meissner's
nerve plexus
Muscularis propria

External longitudinal muscle

Internal circular muscle

Parasympathetic ganglia forming Auerbach's
nerve plexus lies b/w them

Upper 1/3: striated muscle

Middle 1/3: striated & smooth

Lower 1/3: smooth muscle
Fibrous coat (adventitia)

Layer of loose, supportive fibrous tissue

Conducts major vessels & nerves longitudinally

A serosa formed by visceral peritoneum
replaces adventitia of intra-abdominal segment
of oesophagus
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