ANATOMY OF ORAL CAVITY AND PHARYNX

Dr. Rohit Bhardwaj

THE ORAL CAVITY IS CONVENIENTLY DIVIDED BY THE ARCH FORMED BY

THE TEETH AND GUMS INTO:

1. Oral Vestibule- lies between the gums and the teeth.

2. Oral Cavity Proper- lies behind and within the arch of teeth.

THE ORAL VESTIBULE

Boundaries:1. Anteriorly by

the lips,2. Laterally by the

cheeks,3. Superiorly by

the mucolabial and mucobuccal folds, and

4. Posteriorly and medially by the teeth and gums.

THE ORAL CAVITY PROPERBoundaries:1. Anteriorly and laterally by the teeth

and gums,2. Superiorly by the palate (hard and

soft),3. Inferiorly by the tongue and the floor

of the mouth, and4. Posteriorly by the opening into the

pharynx.

THE SUBLINGUAL REGIONCharacteristics:

1. Anterior 2/3 of the tongue,

2. Lingual frenulum,

3. Lingual vein,4. Sublingual

caruncle,5. Sublingual

folds6. Fimbriated

fold

GUMS AND GINGIVAE- consist of dense vascular fibrous tissue

which is covered by mucous membrane and is attached to the alveolar margins of the jaw.

- they are continuous with the mucosa of the oral vestibule externally and the palate or the floor of the mouth internally.

HARD AND SOFT PALATE

The palate forms the superior wall or the roof of the oral cavity proper.

It is composed of the hard palate which has an osseous base, and behind, a soft palate composed of fibrous tissue.

THE HARD PALATE

Covered by mucoperiosteum and forms a partition between the oral and nasal cavities.

Mucoperiosteum is thin in the middle but thicker at the sides due to the presence of numerous glands

Formed by the palatine process of the maxilla and the horizontal plate of the palatine bone.

CHARACTERISTIC FEATURES:Median raphe is a longitudinal ridge extending from the uvula to the incisive papilla.Incisive papilla is a small projection of the mucosa indicating the location of the incisive foramen and the anterior limit of the median raphe.

Transverse palatine process or palatine rugae are about six distinct elevation crossing the anterior part of the hard palate.

Fovea palatine are small inconstant pits on the posterior margin of the hard palate on either side of the median raphe.

THE SOFT PALATEIs the posterior movable portion

of the palate, extending from one side of the pharynx to the other, and attached to the posterior border of the hard palate.

THE SOFT PALATE

CHARACTERISTIC FEATURES:1. Uvula is the median conical

projection marked by median raphe.

2. Palatine arches are free margins of the soft palate and splitting into two parts as they approach the lateral wall.Palatoglossal arch or anterior pillar of fauces or anterior palatine arch encloses the palatoglossus muscle.Palatapharyngeal arch or posterior pillar of fauces or posterior palatine arch encloses the palatopharyngeus muscle.

MUSCLES OF THE SOFT PALATE

Muscle Origin Insertion Action

Palatopharyn-geus

Palatal aponeurosis

Lateral wall of the pharynx and posterior border of the thyroid cartilage

Elevates the pharynx and larynxCloses the oropharyngeal isthmus

Palatoglossus Palatal aponeurosis

Dorsum and lateral aspect of the tongue

Closes the oropharyngeal isthmus

Uvular Posterior nasal spine

Uvula Raises the uvula to help seal oral from nasal pharynx

MUSCLES OF THE SOFT PALATE

Muscle Origin Insertion Action

Levator veli palatini

Medial aspect of the auditory tube

Directly into the palatine aponeurosis

Elevates palate during swallowing, yawning

Tensor veli palatini

Lateral aspect of the membranous portion of the auditory tube, scaphoid fossa of the sphenoid bone

Tendon hooks under hamulus and inserts into the palatal aponeurosis

Tenses the palate and opens the mouth of auditory tube during swallowing and yawning

THE TONGUE A mobile mass of muscles lying

on the floor of the mouth and associated with the function of taste, chewing, swallowing, and speaking.

CHARACTERISTIC FEATURES:1. Root is the lower portion of the

posterior half of the tongue through which the extrinsic muscles, blood vessels and nerves become connected with the organ. It is attached to the mandible and the hyoid bone.

THE TONGUE2. Body anterior part of the tongue,

made up of interlacing skeletal muscles.

3. Margins are the lateral portion of the tongue, free and blunt, in relation to the gums and teeth.

4. Tip or apex is the pointed and free anterior end.

5. Inferior surface is seen when the tongue is turned upwards.

THE TONGUE

6. Dorsum linguae is slightly convex antero-posteriorly, divided into 2 parts by a V-shaped groove – the SULCUS TERMINALIS or LINEA TERMINALIS.Parts:Palatine part is visible when the mouth is opened, covered by papillae.Median sulcus is a faint groove separating the palatine part into symmetrical parts.Foramen caecum is a small pit at the apex of the sulcus terminalis.Pharyngeal part is the posterior 1/3s of the tongue which contains serous glands and nodules of lymphoid tissue – LINGUAL FOLLICLES.Glosso-epiglottic fold is the reflection of the mucous membrane of the tongue on to the epiglottis producing elevation.

THE LINGUAL PAPILLAE 1. Vallate or circumvallate papillae are the

largest, numbering from 7-12, and are arranged in front of the sulcus terminalis.

2. Fungiform papillae are fewer in number and are limited to the tip and margins of the tongue.

3. Filiform papillae are the smallest and the most numerous, scattered all over the anterior 2/3 of the dorsum of the tongue.

THE TASTE BUDSThese are receptor organs for the special sensation of taste.

They are pale oval bodies most of which are located surrounding the vallate papillae; a few are found on the fungiform and foliate papillae.

A few taste buds are scattered through the epithelium of the oral surface of the soft palate, the posterior wall of the pharynx, and the epiglottis.

THE MUSCLES OF THE TONGUE

Extrinsic muscles are responsible for changing position of the tongue.Muscle Origin Insertion Action

Genioglossus Genial tubercle of mandible

Tongue Retract and depress the tongue

Hyoglossus Hyoid bone Posterior half of the side of the tongue

Depress the tongue

Styloglossus Styloid process of temporal bone

Whole length of the tongue

Pull the tongue upwards and backwards

THE MUSCLES OF THE TONGUEThe Intrinsic Muscles:

1. Superior and inferior longitudinal muscles

- Located close to the dorsum of the tongue- Shorten the length of the tongue and to curl

the tip of the tongue and back.2. Transverse muscles

- narrows the tongue.3. Vertical muscles

- flattens the tongue.

A SUMMARY OF THE ACTIONS OF THE TONGUE

1. Protrussion : genioglossus2. Retrussion : hyoglossus,

styloglossus, genioglossus3. Depression : genioglossus,

hyoglossus4. Elevation : styloglossus5. Shortening : longitudinal intrinsic

fibers6. Narrowing : transverse intrinsic

fibers7. Flattening : vertical intrinsic fibers

CLINICAL NOTES

TONGUE PARALYSISFractured mandible may damage the hypoglossal nerve to pull the tongue to the same side.

General anesthesia results in looseness, or flaccidity, of muscles.

A paralyzed or flaccid tongue tends to fall back into the airway, causing suffocation, unless a patent airway is maintained.

TONGUE TIE

A large lingual frenulum can limit the mobility of the tongue and interfere with speech. The condition is easily repaired by cutting the frenulum (lingual frenectomy).

THE SALIVARY GLANDS AND ACCESSORY GLANDS OF THE ORAL CAVITY

THE SALIVARY GLANDS OF THE ORAL CAVITY

1. Parotid Gland

2. Submandibular Gland

3. Sublingual Gland

THE PAROTID GLANDThe parotid gland is one of the three

major salivary glands that produce and secrete saliva for the oral cavity.

weight: about 14 to 28 g.

color : yellowish in the fresh state

composition: serous secreting units

LOCATION AND RELATIONS OF THE PAROTID GLANDA. Anterior surface: lies against the

posterior border of the ramus of the mandible

B. Posterior surface: on the external auditory meatus and sternocleidomastoid muscle

LOCATION AND RELATIONS OF THE PAROTID GLAND

B. Superficial surface: lobulated, covered by skin, fascia, lymph nodes, and facial branches of the great auricular nerve.

C. Deep surface: styloid process and its muscles as well as under the mastoid and sternocleidomastoid muscles.

CAPSULE OF THE PAROTID GLAND The gland is wrapped in a fibrous

capsule, which is continuous with the deep investing fascia of the neck.

The stylomandibular ligament is an anterior thickening of the capsule, which runs from the styloid process to the angle of the mandible. –

It separates the parotid gland from the infratemporal fossa anteriorly and separates the parotid gland from the submandibular gland inferiorly and anteriorly.

THE PAROTID DUCT From the rostral border of the gland,

crosses masseter muscle, turns inward to pierce the fat pad of the cheek and then the buccinator muscle, to open into the mouth opposite the second maxillary molar.

Approximately 5 cm. long.

CLINICAL CONSIDERATIONS1. A viral inflammation of the parotid

gland (mumps) causes it to swell, resulting to pain on movement of the jaw.

2. Abcesses or cysts of the gland may result in pressure to the facial nerve

3. Stones or calculi in the duct can block it, causing painful swelling of the gland.

THE SUBMANDIBULAR GLANDType: It is a mixed serous and mucous

secreting gland.

Location: It is found partly in the submandibular

fossa below the mylohyoid muscle and partly in the floor of the mouth.

THE SUBMANDIBULAR GLANDDuct:The submandibular duct (Wharton’s)

arises from the medial surface of the gland and accompanies it under the mlohyoid muscle; it passes diagonally across the medial aspect of the sublingual gland and adheres to it. It opens at the sublingual papillae (sublingual caruncle) beside the base of the lingual frenulum.

THE SUBLINGUAL GLAND The smallest of the three major salivary

glands and rests upon the mylohyoid muscle in the sublingual fossa close to the symphysis. It is primarily a mucous secreting gland.

THE SUBLINGUAL GLANDLocation:The gland, indicated by the subligual fold is found between the alveolus and the anterior part of the tongue.

Ducts:The gland has many lesser sublingual ducts (Rivini’s) that opens separately at the floor of the mouth and a greater sublingual duct (Bartholin’s) that opens on the sublingual caruncle together with the Wharton’s duct.

THE ACCESSORY GLANDSBeside the main salivary glands, many others exists: some in the tongue, others around and in the palatine tonsil between its crypts, with the large number in the soft palate, the posterior part of the hard palate, the lips and the cheeks. These are similar in structure to larger salivary glands and are mainly mucous type.