Anatomy of Oral cavity and Pharynx

Dr Mohit GoelJR1

22 aug. 2012

Oral Cavity

2 parts:

1] Oral vestibule

2]Oral cavity proper

Oral vestibule = slit space between teeth- buccal gingiva

and lips-cheek .

>Vestibule communicates with exterior through mouth.

>Size of opening is controlled circumoral muscles such as

orbicularis oris, buccinator,depressors and elevators of

lips.

ORAL CAVITY PROPER

It is the cavity within the

alveolar margins of the

maxillae and the

mandible

Its Roof is formed by the

hard palate anteriorly

and the soft palate

posteriorly

Its Floor is formed by the

mylohyoid muscle. The

anterior 2/3rd of the

tongue lies on the floor.

hard

soft palate

mylohyoid

FLOOR OF THE MOUTH

Covered with mucous membrane

In the midline, a mucosal fold, the frenulum, connects the tongue to the floor of the mouth

On each side of frenulum a small papilla has the opening of the duct of the submandibular gland

A rounded ridge extending backward & laterally from the papilla is produced by the sublingual gland

NERVE SUPPLY

oSensory Roof: by greater palatine and nasopalatine nerves

(branches of maxillary nerve)

Floor: by lingual nerve (branch of mandibular nerve)

Cheek: by buccal nerve (branch of mandibular nerve)

oMotor Muscle in the cheek (buccinator) and the lip

(orbicularis oris) are supplied by the branches of the facial nerve

MUSCLES

The tongue is

composed of two

types of muscles:

• Intrinsic

• Extrinsic

Mylohyoid

The main muscle forming the floor of the mouth is mylohyoid.

GENIOHYOID

Geniohyoid is a narrow muscle which lies above the medial part of . It

arises from the inferior mental spine (genial tubercle) on the back of the

symphysis menti, and runs backwards and slightly downwards to attach to

the anterior surface of the body of the hyoid bone.

Genioglossus

It arises from a short tendon attached to the superior genial tubercle behind

the mandibular symphysis, above the origin of geniohyoid. From this point it

fans out backwards and upwards.

Hyoglossus

Hyoglossus is thin and quadrilateral, and arises from the whole length of the

greater cornu and the front of the body of the hyoid bone. It passes vertically

up to enter the side of the tongue between styloglossus laterally and the

inferior longitudinal muscle

medially.

Styloglossus

It arises from the anterolateral

aspect of the styloid process near

its apex

Passing downwards and forwards,

it divides at the side of the tongue

into a longitudinal part, which

enters the tongue dorsolaterally to

blend with the inferior longitudinal

muscle in front of hyoglossus, and

an oblique part, overlapping

hyoglossus and decussating with

it.

Tip:Submental nodes bilaterally & then deep cervical nodes

Anterior two third:Submandibular unilaterally & then deep cervical nodes

Posterior third:Deep cervical nodes (jugulodigastricmainly)

Lymphatic Drainage

Classification of Neck Nodes According to Levels

Level I

Level II

Level III

Level IV

Level V

Level VI

Level VII

Submental (IA)

Submandibular (IB)

Upper jugular

middle jugular

Lower jugular

Posterior triangle group

(Spinal accessory and

transverse cervical

chains)

Prelaryngeal

Pretracheal

Paratrachal

Nodes of upper mediastinum

PHARYNX

Extends from the base of the skull to the lower border of

the cricoid cartilage (at which point it border of the

cricoid cartilage (at which point it becomes the

oesophagus).

Portions of the pharynx lie

posterior :

• nasal cavity (nasopharynx)

• oral cavity (oropharynx)

• larynx (laryngopharynx)

Nasopharynx

Roof : body of sphenoid,

basilar part of occipital,

bone pharyngeal tonsil

Floor: soft palate,

pharyngeal isthmus

Anterior wall : post. nasal

apertures

Posterior wall: ant. arch of atlas

Lateral wall : auditory tube , tubal elevation , salpingo

pharyngeal fold and tubal tonsil

Oropharynx

Roof : soft palate,

pharyngeal isthmus

Floor : post. 1/3 tongue,

epiglottis, lingual tonsil,

median glossoepiglottic fold,

2 lateral glosso epiglottic

Fold and vallecula.

Anterior wall : mouth, tongue

Posterior wall : C2,C3

Lateral wall : palatoglossal , palatopharyngeal

arches/folds and palatine tonsils

Laryngo pharynx

• Walls:

Ant. – inlet of pharynx

Post. – C3 – C6

Lat. – thyroid cartilage

The pharyngeal muscles are a group of muscles that act upon the pharynx.

They include:

Inferior constrictor muscle

Middle constrictor muscle

Superior constrictor muscle

Stylopharyngeus muscle

Salpingopharyngeus muscle

Palatopharyngeus muscle

MRI

BUCCINATOR

MASSETER

INTRINSIC MUSCLE OF

TONGUE

GENIOGLOSSUS

MYLOHOID

LINGUAL SEPTUM

GENIOHYOID

DIGASTRIC

PLATYSMA

HARD PALATE

TONGUE

HYOGLOSSUS M.

LINGUAL TONSIL

SUBMANDIBULAR GLAND

GLOSSOEPIGLOTIC FOLD

DIGASTRIC M.

PLATYSMA

NASOPHARYNX

PAROTID GLAND

UVULA

PALATINE TONSIL

DIGASTRIC MUSCLE

SUBMANDIBULAR GLAND

PLATYSMA

LATERALPTERYGOID

MEDIAL PTERYGOID

HARD PALATE

NASOPHARYNX

SUPERIOR CONSTRIC. M

SOFT PALATEINTRINSIC MUSCLE OF TONGUE

MIDDLE CONSTRIC. M.

GENIOGLOSSUS

MYLOHOID

OROPHARYNX

EPIGLOTIS

HYPOPHARYNX

INFERIOR CONSTRICTOR M.

Buccinator m.

Hard palate

Masseter muscle

Lateral & medial pterygoid

m.

Nasopharynx

Longus capitis muscle

Buccinator m.

Tongue(genioglossus m.)

Masseter muscle

Medial pterygoid m.

Palatine tonsil

Oropharynx

Longus capitis muscle

Orbicularis oris

Hyoglossus

Genioglossus

Mylohoid

Oropharynx

Submandibular gland

Palatopharyngeus m.

Superior constrictor m.

Orbicularis oris

Hyoglossus

Genioglossus

Mylohoid

Epiglotis

Hypopharynx

Submandibular gland

Palatopharyngeus m.

Middle constrictor m.

Mandible

Digastric m.

Mylohyoid

Geniohyoid

Hyoid bone

Submandibular gland

Epiglotis

Hypopharynx

Piriform recess

Inferior constrictor m.

SUBLINGUAL SPACE

Paired non-fascial lined spaces of oral cavity in deep oral tongue above floor of

mouth superomedial to mylohyoid muscle

Communication between sublingual spaces occurs in midline anteriorly as a

narrow isthmus beneath frenulum

o SLS communicates with SMS(submandibular space) and inferior para

pharyngeal space (PPS) at posterior margin of mylohyoid muscle

• There is no fascia dividing posterior

SLS from adjacent SMS.Therefore there is direct

communication with SMS and PPS in this location.

Posterior aspect of SLS is divided into medial

and lateral compartments by hyoglossal

muscle.

Clinical Importance

• Since neurovascular bundle to tongue travels

in SLS,oral cavity SCCa involving posterior SLS is

challenging to treat.

• If SCCa crosses lingual septum to contralateral

SLS, lesion becomes unresectable for cure.

SUBMANDIBULAR SPACE

Fascial-lined space inferolateral to mylohyoid muscle containing

submandibular gland, nodes and anterior belly of digastric muscles.

SMS is defined as a superficial space above hyoid bone deep to platysma and

superficial to mylohyoid sling . Continues inferiorly into infrahyoid neck as

anterior cervical space.

Inferolateral to mylohyoid muscle of floor of mouth

• Deep to platysma muscle

• Cephalad to hyoid bone

• "Vertical horseshoe-shaped" space between hyoid bone below and

mylohyoid

sling above.

• SMS communicates posteriorly

with sublingual space and inferior

para pharyngeal space at

posterior margin of mylohyoid

muscle.

• Continues inferiorly into infrahyoid

neck as anterior cervical space.

RETROMOLAR TRIGONE

Triangle-shaped area of mucosa posterior to last mandibular molar that covers

anterior surface of lower ascending ramus of mandible.

Pterygomandibular raphe (PMR)-

Thick fascial band that extends between posterior border of mandibular

mylohyoid ridge and hamulus of medial

pterygoid plate.

It represents thickening of middle layer of

deep cervical fascia condensed between

posterior margin of buccinator muscle and

anterior margin of superior constrictor

muscle.

Clinical Importance

• SCCa (squamous cell ca.) of RMT may spread along PMR

(Pterygomandibular raphe ).

o Cephalad spread along PMR takes tumor up to inferolateral pterygoid

plate- Anteromedial masticator space.

• Tumor is seen at level of inferior pterygoid Plate involving posterior

buccinator muscle and anterior superior constrictor muscle.

• Enlarging tumor involves maxillary sinus, Buccal and masticator spaces.

o Caudal spread along PMR takes tumor inferiorly to posterior margin of

mylohyoid m.

• Enlarging tumor in this location involves floor of mouth of oral cavity.

THANK U