The Oral Cavity I

8/2/2019 The Oral Cavity I

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The Oral Cavity I


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THE MOUTH

The mouth is enclosed between the lips andthe cheeks.

It extends from the lips to the oropharyngealishthmus. (the junction of mouth with thepharynx).


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FunctionsThe function of the mouth and its

associated structures is

to form a receptacle for food,

to begin mechanical digestionthrough chewing (mastication), and

to form words in speech.

It can also assist the respiratory

system in the passage of air.


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The mouth is divided into two parts:

1-VESTIBULE.

2-MOUTH CAVITY PROPER.

Vestibule lies between the lips and cheeks externally and the gumsVestibule lies between the lips and cheeks externally and the gums

and teeth internally.and teeth internally.

Mouth cavity proper is the space inside the teeth and gums.Mouth cavity proper is the space inside the teeth and gums.


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THE VESTIBULE The vestibule is a slit like space that

communicates with the exterior through the oralfissure.

It leads, by the space behind the teeth ,into thecavity of the mouth. Superiorly and inferiorly the vestibule is limited

by the mucous membrane.

The cheek forms the lateral wall of the vestibule.It is made up of buccinator muscle. On the mucous membrane of the cheek ,the

parotid duct opens on a low papilla opposite the

second molar teeth.


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THE MOUTH CAVITY

PROPER ROOF: Formed by the hard and soft palate.

FLOOR: Largely occupied by tongue.

The frenulum of the tongue connects theundersurface of the tongue with the floor ofthe mouth.


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Parts of the oral cavity Hard & Soft palate TongueAlveolar margins of maxillae & mandible Teeth Gums Cheek


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The palate It forms the arched roof of the oral cavity &

the floor of the nasal cavities

On the nasal side it is lined by respiratorymucosa & on the oral side by oral mucosa,densely packed with glands

It consists of the hard palate anteriorly & thesoft palate posteriorly


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The hard palate Concave towards the oral side

Filled with tongue when at rest The ant 2/3 has a bony skeleton

formed by

Palatine process of maxilla Horizontal plates of palatine bones


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Features of the hard palate Incisive fossa behind the central

incisors. Structures passing fromnasal to oral side

Nasopalatine nerves

They enter the incisive canals


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Features of the hard palate The greater palatine foramen medial to

3rd molar for the passage of

Greater palatine vessels and nerveswhich emerge & run forwards to supplythe molars, premolars, canines & the

palatine mucosa


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The lesser palatine foramen throughwhich the following structures pass Lesser palatine vessels and nerves to

supply the soft palate

The hard palate


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The hard palate

Mucosa. Firmly adherent to the bone. Lingual gingiva is continuous with the mucosa

An injection of local anaesthetic into gingivaalso anaesthetises the palate

Deep to mucosa are mucous secretingpalatine glands, hence the pitted appearance


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The hard palate

Posterior to maxillary incisor teeth is incisivepapilla, an elevation of mucosa anterior tounderlying incisive foramen

Several transverse folds radiate from thepapilla, the transverse palatine folds or rugae

Central white ridge, the palatine raphe,marksthe site of embryonic fusion ofbones.


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The hard palate

incisive papilla

transverse palatine

folds or rugae palatine raphe

Soft palate

uvula


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Cleft palatesPartial cleft Complete cleft


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The soft palate

It is the movable posterior third ofpalate

It hangs from the post border of hard

palate The expanded tendon of tensor veli

palatini muscle forms a strongaponeurosis, the palatine aponeurosis

which is attached to the post border ofhard palate.


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The soft palate The soft palate extends posteriorly as a

free margin The central part hangs as a conical

process called uvula The strength of the soft palate comes

from palatine aponeurosis which isthick anteriorly & thin posteriorly


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The soft palate

During swallowing the softpalate is tensed to push the

bolus into oropharynx, then it iselevated to prevent the foodfrom entering into nasal cavity

Laterally it is continuous withthe tongue & pharynx by palatoglossal &palatopharyngeal folds


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Oral cavity showing the palate


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The soft palate

Soft palate Uvula

Palatine tonsil Palatoglossal fold Palatopharyngeal

fold Dorsum of the

tongue


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The fauces

The space b/w oropharynx & oral cavity

Faucial pillars

The isthmus of the fauces

Tonsillar sinus or fossa


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Muscles of the soft palate

Tensor & levatorarise from the

cranial base & areinserted into thepalate

They can elevate,

tense or depress thesoft palate


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Tensor veli palatini

Levator veli palatini

Palatoglossus

Palatopharyngeus

Musculus uvulaeThe last three arise from the palate


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Tensor veli palatini

Origin Scaphoid fossa Spine of sphenoid Cartilage of the auditory tube Takes a 90 degree bend around

hamulus

Insertion

Palatine aponeurosis


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Actions

Tenses the soft palate

Opens the mouth of auditory tubeduring swallowing & yawning

Nerve supply

Medial pterygoid nerve via otic ganglion


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Levator veli palatini

Origin

Cartilage of the auditory tube

Petrous part of temporal bone

Insertion Palatine aponeurosis


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Actions

Elevates soft palate during swallowing

& yawning Nerve supply

Pharyngeal branch of vagus viapharyngeal plexus


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Palatoglossus

Origin


Insertion

Side of the tongue


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Actions

Brings posterior part of the tongue &

soft palate together Nerve supply



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Palatopharyngeus

Origin

Hard palate


Insertion Lateral wall of pharynx


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Actions Tenses the soft palate Brings pharyngeal walls forwards,

medially & superiorly Nerve supply



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Musculus uvulae

Origin

Post nasal spine & palatine aponeurosis

Insertion

Own mucosa


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Actions

Shortens uvula & pulls it up

Nerve supply



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Palatine tonsils inflamed


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Blood supply of the palate

Greater palatine arterya branch ofdescending palatineartery. It also givesoff

Lesser palatine artery

Ascending palatine

artery from facialartery


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Sensory nerves of the palate

These are branches of maxillary nervethrough pterygopalatine ganglion

Nasopalatine nerve. Greater palatine nerve.

Lesser palatine nerve.


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THE TONGUE


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The Tongue Muscular organ, mobile & can adapt manypositions & shapes About 2/3 is in the oral cavity & the rest in

oropharynx

Its functions are Taste Mastication Swallowing

Cleansing Speech or articulation


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Parts of the tongue

Apex, is the tip & is highly mobile Body, ant 2/3,highly mobile

Root, post. 1/3

Curved dorsum Inferior surface


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The Tongue


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Dorsal surface of the tongue

Curved & partly in the oral cavity &partly in pharynx

V shaped sulcus terminalis marks theboundry

Points towards foramen caecum

Remnant of embryonic thyroglossalduct


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The margins are in relation to lingual gingivae Mucous membrane on ant. 2/3 is rough due to

the presence of lingual papillae. Most of thesecontain taste buds

Vallate papillae: Large & flat, make a V shapedrow in front of sulcus terminalis

Each is surrounded by a trench into which the

ducts of the serous glands open


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Foliate papillae:Small leaf like folds,poorly developed

Filiform papillae: V-shaped rows ofconical projections,pinkish in colour &sensitve to touch


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Fungiform papillae: Numerous at the

apex & margins. Shaped likemushroom, pink to red in colour


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M. memb over the dorsum is thin & adherentto the muscle anteriorly

Shallow midline groove indicates site of

fusion of distal buds Posteriorly the m. memb. is thick & movable.

No papillae, but irregular appearance due tounderlying lymphoid follicles

Collectively they are known as lingual tonsils.


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Inferior surface of tongue

Thin transparent m. memb Veins visible

Midline fold called frenulum

On each side a deep lingual vein & asublingual papilla is visible

Opening of the sublingual salivary gland onthe summit of the papilla


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Muscles of the tongue

Two groups

Extrinsic: Alter the

position of thetongue

Intrinsic: Alter the

shape of thetongue


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EXTRINSIC M: Genioglossus: Fan shaped

Origin

Mental spine or genial tubercle on mandible Insertion

Under surface of the entire dorsum

Body of the hyoid


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Hyoglossus: Thin quadrilateral

Origin

Body & greater horn of hyoid bone

Insertion

Inferior aspect of the lateral part


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Styloglossus: Short & triangular Origin

Ant. Border of styloid process Stylohyoid lig. Insertion

Post. Part of the side of the tongue,interdigitates with hyoglossus


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Palatoglossus: Narrow sickle shaped Origin


Insertion Enters post part of lateral margins

transversely & becomes continuous

with intrinsic transverse mm.


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Muscles of the tongueThere is a vertical fibrous septum that

runs anteroposteriorly from the base tothe tip.

INTRINSIC muscles are:

Sup longitudinal m. Oblique fibreslying beneath the dorsal mucosa.Extends from submucous fibrous tissue

& the median septum to the margins ofthe tongue.


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Muscles of the tongue Inf. Longitudinal m

Narrow band close to inf. mucosa fromthe root to the apex.

Transverse muscle

From median fibrous septum to thelingual margins.

Vertical muscle

From dorsal to ventral mucosa in theant. & lat. Parts of tongue.


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Nerve supply

All are supplied by the hypoglossal n. Actions

They alter the shape of the tongue Longitudenal m. shorten the tongue. They can turn

the apex upwards or downwards Transverse m narrow & elongate the tongue Vertical muscles widen & flatten the tongue


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Muscles of thetongue

N i l ti t th


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Nerves in relation to thelingual muscles


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Blood supply of the tongue

Arteries Lingual artery

Ascending palatine branch of facial Ascending pharyngeal a.

Venous drainage Dorsal lingual vein IJV Deep lingual vein + sublingual vein vena

comitans nervi hypoglossi joins either facial orlingual v IJV


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Vessels of the tongue


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Lymphatic drainage of the tongue

Lymphatic plexus in the lingual mucosa Muscular lymphatic plexus

Both plexuses are connected & drain

into marginal lymph vessels from apex to

frenula enter submental,

juguloomohyoid, submandibular &jugulodigastric nodes deep cervicalnodes


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Lymphatic drainage of the tongue

Central lymph vessels Jugulodigastric,jugulo-omohyoid & submandibular

nodes deep cervical nodes Dorsal vessels drain the region

behind the vallate papillae they join

the marginal vessels deep cervicalnodes

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The Oral Cavity I