Oral Region Dr. Haydar Muneer Salih

• Oral cavity is the first part of digestive tract1.Ingestion and swallowing 2.Speech3.Respiration • It is divided into two parts:1. Oral cavity proper2. The vestibule

Oral Cavity Proper• It is the space between the upper and the

lower dental arches • It is limited laterally and anteriorly by the

dental arches. The roof of the oral cavity is formed by the palate. Posteriorly, the oral cavity communicates with the oropharynx (oral part of the pharynx). When the mouth is closed and at rest, the oral cavity is fully occupied by the tongue

The oral vestibule• The oral vestibule is the slit-like space

between the teeth and gingivae (gums) and the lips and cheeks. The vestibule communicates with the exterior through the oral fissure (opening).• The size of the oral fissure is controlled by

the circumoral muscles

Lips • Each lip is largely composed of orbicularis oris

muscle. In addition it contains labial (mucous) glands and blood vessels. It is lined externally by skin which contains sweat glands and sebaceous glands with hair follicles (The hairs are thicker and more numerous in adult males). They are lined internally with mucus membrane. The mucocutaneous junction appears as a reddish pink area visible externally

• Arterial supply of lips is derived from superior and inferior labial arteries, branches of facial artery.• Lymphatics of lips drain into the following lymph nodes:a. Submandibular lymph nodeb. Submental lymph nodes• Skin of lips is innervated by branches of infraorbital nerve (upper lip) and mandibular nerve (lower lip). Muscles are supplied by facial nerve.

CheekCheeks are the fleshy flaps which lie over maxilla and mandible and form a large part of the face. Each cheek is continuous in front with the lip. The junction between the two is marked by the nasolabial sulcus or the furrow which extends from the side of the nose to the angle of the mouth. Like the lips the cheeks are lined externally by skin and internally by mucous membrane

From superficial to deep:1. Skin2. Superficial fascia containing muscles of facialexpression3. Buccinator4. Buccal pad of fat5. Buccopharyngeal fascia6. Submucosa, containing buccal (mucous) glands7. Mucous membrane

Structure & layers of the cheek :

• Arterial supply of cheeks is derived from buccal branch of maxillary artery.• Lymphatics from cheek drain into submandibular and preauricular lymph nodes.• Skin of cheek is innervated by : zygomaticofacial and infraorbital branches of maxillary nerve, mucus membrane is supplied by buccal branch of mandibular nerve. Muscles are supplied by facial nerve

Oral Mucosa

The mucosal lining of oral cavity continues with the skin of lips anteriorly and mucosa of oropharyx posteriorly. It can be divided into three types according to the anatomical location and function1.Lining mucosa2.Masticatory mucosa3.Specialized mucosa

1 .Lining mucosa:It consists of non-keratinized stratified squamous epithelium. It lines the inner aspect of lips and cheeks, covers soft palate, ventral surface of tongue, floor of mouth and lower part of upper and lower alveolar processes (jaws). It overlies a loose layer of lamina propria and has submucosa which contains fat and minor salivary glands

2 .Masticatory mucosa:• It is the mucosa that lines the upper part of

alveolar process, neck of teeth and the hard palate. It consists of keratinized stratified squamous epithelium with minimal lamina propria that has connective tissue fibers which adhere the epithelium to the underlying bone. There is no submucosa. This modification• allows the epithelium to bear the stress of

mastication

Gingiva (Gum)

Gingiva is the masticatory mucosa that covers the alveolar processes of maxilla (upper jaw) and mandible (lower jaw) and surrounds the neck of teeth. It can be divided into two parts:1. Attached gingiva: It is firmly bound to the periosteum of the alveolar bone and tooth.2. Free or unattached gingiva: It is the distal 1 mm margin of gingiva that surrounds the neck of the tooth and is not attached to the bone.

• The gingival tissues derive their blood supply from branches of maxillary artery (supplies the buccal and labial surfaces) and lingual artery (supplies the lingual surfaces).• Lymphatics from gingivae drain into submandibular lymph nodes.• Gingivae of upper jaw are supplied by branches of maxillary nerve while of lower jaw are supplied by branches of mandibular nerve

3 .Specialized mucosa:It is the mucosa which covers the dorsal surface of tongue. It consists of stratified squamous non-keratinized epithelium which is directly adherent to the underlying muscles. There is no submucosa. It gives rise to a number of projections called lingual papillae which are described ahead with tongue.

TONGUE• Tongue is a mass of striated muscle covered

with mucous membrane. The muscles attach the tongue to the styloid process and the soft palate above and to the mandible and the hyoid bone below, the tongue is divided into right and left halves by a median fibrous septum

• The V-shaped sulcus serves to divide the tongue into the anterior two thirds, or oral part, and the posterior third , or pharyngeal part.

• The mucous membrane covering the posterior third of the tongue is devoid of papillae but has an irregular surface, caused by the presence of underlying lymph nodules, the lingual tonsil. • the undersurface of the tongue is

connected to the floor of the mouth by a fold of mucous membrane, the frenulum of the tongue

Muscles of the TongueThe muscles of the tongue are divided into two types: intrinsic and extrinsic. 1-Intrinsic MusclesThese muscles are confined to the tongue and are not attached to bone. They consist of longitudinal, transverse, and vertical fibers.Nerve supply: Hypoglossal nerveAction: Alter the shape of the tongue

2-Extrinsic MusclesThese muscles are attached to bones and the soft palate. They are the genioglossus, the hyoglossus, the styloglossus, and the palatoglossus.Nerve supply: Hypoglossal nerveExcept the palatoglossus which innervated by pharyngeal plexus ( CN X)

Sensory Innervation

Anterior two thirds: Lingual nerve branch of mandibular division of trigeminal nerve (general sensation) and chorda tympani branch of the facial nerve (taste)Posterior third: Glossopharyngeal nerve (general sensation and taste)A small posterior region receives sensory innervation from CN X.

Blood SupplyThe lingual artery, the tonsillar branch of the facial artery, and the ascending pharyngeal artery supply the tongue. The veins drain into the internal jugular vein.Lymph DrainageTip: Submental lymph nodesSides of the anterior two thirds: Submandibular and deep cervical lymph nodesPosterior third: Deep cervical

Movements of the Tongue

Protrusion: The genioglossus muscles on both sides acting together Retraction: Styloglossus and hyoglossus muscles on both sides acting togetherDepression: Hyoglossus muscles on both sides acting togetherRetraction and elevation of the posterior third: Styloglossus and palatoglossus muscles on both sides acting togetherShape changes: Intrinsic muscles

PALATE

It is an osteomuscular partition between nasal and oral cavities. It also separates nasopharynx from oropharynx.The palate consists of two parts:1. Hard palate: It forms the anterior 2/3rd of the palate.2. Soft palate: It forms the posterior 1/3rd of the palate

• The hard palate forms a partition between the nasal and oral cavities.

• The anterior 3/4th is formed by the palatine processes of the maxillae and the posterior 1/4th by the horizontal plates of the palatine bones.

• The superior surface of hard palate forms the floor of nasal cavity and is lined by the ciliated pseudostratified columnar epithelium.

• The inferior surface of hard palate forms the roof of oral cavity and is lined by masticatory mucosa. It presents with a median palatine raphe

• Arterial supply of hard palate is dervied from greater palatine artery, branch of maxillary artery and ascending palatine branch of facial artery. The veins drain into pterygoid plexus of veins.

• Nerve supply of hard palate is derived from greater palatine and nasopalatine branches of maxillary nerve through pterygopalatine ganglion.

Soft Palate

The soft palate is a mobile muscular fold suspended from the posterior border of the hard palate like a velum. It is lined by nonkeratinized stratified squamous epithelium which encloses muscles, vessels, nerves, lymphoid tissue and mucous glands. It appears red in comparision with the hard palate which is pink. It separates the nasopharynx from oropharynx.

• On each side, from the base of uvula, two curved folds of mucous membrane extend laterally and downwards along the lateral wall of oropharynx.

These are:i. Palatoglossal foldIt is the anterior fold which merges inferiorly with

the sides of the tongue at the junction of its oral and pharyngeal parts.

ii. Palatopharyngeal foldIt lies posterior to the palatoglossal fold and merges

inferiorly with the lateral wall of the pharynx.

Muscles of the Soft Palate The soft palate consist of five pairs of muscles:Tensor veli palatini Levator veli palatini PalatoglossusPalatopharyngeusMusculus uvulae

Functions of the Soft Palate

1. Separates the oropharynx from nasopharynx during swallowing so that food does not enter the nose.2. Isolates the oral cavity from oropharynx during chewing so that breathing is unaffected.3. Helps to modify the quality of voice, by varying the degree of closure of the pharyngeal isthmus. 

Arterial Supply of Soft PalateIt is supplied by the following arteries:1. Ascending palatine artery, branch of facial artery.2. Palatine branch of ascending pharyngeal artery.3. Greater palatine artery, branch of maxillary artery.Venous Drainage of Soft PalateVeins drain into the pterygoid plexus of veins. .

Lymphatic Drainage of Soft PalateLymphatics from soft palate drain into the following nodes:1. Retropharyngeal nodes.2. Deep cervical lymph nodes

Nerve Supply of Soft Palate1. Motor supply: All muscles of palate are supplied by cranial part of accessory nerve via pharyngeal plexus except tensor veli palatini which is supplied by nerve to medial pterygoid, a branch of mandibular nerve.2. Secretomotor Supply to Palatine Glands (preganglionic and postganglionic fibers).3. Sensory supply: The afferents pass toa. Greater and lesser palatine nervesb. Sphenopalatine nervesc. Glossopharyngeal nerves