Oral Cavity Dr. Shawky M. Tayel By - Professor of Anatomy, Embryology & Human Genetics Anatomy Dep., Alexandria Faculty of Medicine, - Genetics Consultant, Clinical Genomic Center www.alexmedicine.com/alexgenomics.htm , - Genetics Consultant, Suzanne Mubarak Regional Centre for Women's Health & Development www.smcalex.org , - Fellow, Medical College of Ohio, USA, - Member, American Society of Human Genetics.

1- Vestibule of mouth: It is a slit like space bound externally by the lips and cheeks, internally by gums and teeth.

2- Mouth cavity proper It is bounded by: Anterior and laterally: the gums and teeth. Posteriorly: it communicates with the pharynx through the isthmus. This isthmus is bounded by the palato-glossal arch on each side. Roof: is formed by the hard and soft palate. Floor: is formed by the anterior 2/3 of the tongue.

Frenulum linguae= A median fold of mucosa connects the under surface of the tongue to the floor of the mouth. The sublingual fold= a small ridge on each side of the frenulum. Lateral to the frenulum there are the lingual vein and lateral to it are the fimbriated folds (one on each side).

Muscles of the floor of the mouth Mylohyoid Geniohyoid Stylohyoid Digastric

Mylohyoid muscle Origin: Mylohyoid line. Insertion: Hyoid bone and mylohyoid raphe. Nerve supply: Mylohyoid nerve. Action: Elevation of hyoid bone,Floor of mouth and tongue. Depression of mandible

Geniohyoid muscle Origin: Inferior genial tubercle. Insertion: Hyoid bone. Nerve supply: C1 (component of hypoglossal nerve) Actions: 1- Elevates hyoid bone. 2- Depresses the mandible.

Stylohyoid Origin: Styloid process. Insertion: Hyoid bone. Nerve supply: Facial nerve. Action: Elevates the hyoid bone.

Digastric muscle Origin: Anterior belly, digastric fossa of mandible. Posterior belly, Mastoid notch. Insertion: Intermediate tendon. Nerve supply: Anterior belly, mandibular nerve. Posterior belly, facial nerve. Actions: Elevation of hyoid bone. Depression of mandible.

Tongue Skeletal muscles covered by mucosa. Lies in the proper mouth cavity and the oropharynx. Functions: Taste, speech, chewing & swallowing. Surfaces: 2 = Dorsum: Faces the palate Divided into oral and pharyngeal parts by the V-shaped sulcus terminalis. IInferior surface: lies in the oral cavity. The tongue also has a margin, tip and root attaching it to the floor of the mouth.

Dorsum of the tongue The Oral part; = the 2/3 anterior to sulcus terminalis. Covered by papillae (which bear taste buds); - Vallate (anterior to sulcus terminalis) - Fungiform (at the edges) - Filiform (scattered)

Pharyngeal part of the dorsal surface: = The 1/3 posterior to sulcus terminalis. Covered by aggregations of lymphoid tissue called Lingual tonsil. Foramen caecum = Blind pouch at the apex of the sulcus terminalis (site of origin of the thyroid diverticulum (thyroglossal duct).

Inferior surface of the tongue; Covered by mucous membrane, showing: - Frenulum lingulae, - Deep lingual vein on each side. - Fimbriated fold (laterally).

Muscles of the tongue Interensic muscles: - longitudinal, - Transverse, - Vertical

Extrinsic muscles of the tongue

Genioglossus: Origin: Sup. Genial tubercle of the mandible Insertion: Into the side of the tongue and hyoid bone Action: Depresses, protrudes, and deviates the tongue to the opposite side. N. Supply Hypoglossal nerve (XII)

Hyoglossus: origin: hyoid bone Insertion: side of tongue Action: depresses the tongue N. Supply: XII nerve

Styloglossus: Origin: styloid process behind ear Insertion: into side of the tongue Action: pulls the tongue upward and back N. supply: XII

Palatoglossus: Origin: palatine aponeurosis Insertion: Lateral surface of the back of the tongue Action: pulls the tongue back to narrows the oropharyngeal ismuthus, Depresses the palate. N. Supply: Pharyngeal plexus of vagus (X) nerve

Nerve supply of the tongue Sensory: Anterior 2/3: Gerneral sensation: Lingual nerve of mandibular of trigeminal. Taste sensation: Chorda tympani (the parasympathetic part of facial (VII) nerve. Posterior 1/3: IX (glossopharyngeal) nerve General and taste). Posterior end of the dorsum: Internal laryngeal n. (from X). Motor: XII to all muscles except palatoglossus.

Arterial supply of the tongue: lingual arterey (which gives 2 dorsalis linguae and deep lingual artery B) venous drainage: lingual vein --- I J V.

Lymphatic drainage The anterior 2/3 …..> submental lymph nodes of both sides Margin …..> submandibular lymph nodes of the same side Posterior 1/3 …..> Upper deep cervical LNs (UDC LN) of both sides.

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