Anatomy of Oral

Cavity, Pharynx &

OesophagusDr. 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 musclesInferior 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

*** except palatoglossus which is supplied by

pharyngeal plexus

Anterior 2/3 Posterior 1/3

Sensory Lingual Glossopharyngeal

Motor Hypoglossal ***

Taste Chorda tympani Glossopharyngeal

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 PassingBetween 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 DrainageUpper 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 + retro-

pharyngeal + parapharyngeal +

posterior triangle

Oropharynx: upper deep cervical + retro-

pharyngeal + 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 hypo-

pharyngeal 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 antero-

posterior 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 ConstrictionsSite Vertebral Level Distance from

central incisor

Cricopharynx C 6 15 cm

Aortic arch T 4 25 cm

Lt main bronchus

T 5 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 SupplyPart Arterial Venous

Cervical Inferior thyroid Inferior thyroid

Thoracic Descending thoracic aorta,

Bronchial

Azygos,Hemi-azygos

Abdominal Left gastric, Inferior

phrenic

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 SupplyCervical: 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 coatPink, 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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