The Mouth The mouth cavity is divided into vestibule &mouth cavity proper. Vestibule of mouthlies between lips + cheeks (buccinator) externally, /and gums + teeth internally. The mouth cavity proper : Boundaries : In front and at the sides : gums & teeth 2- Roof :hard palatein front &soft palatebehind. 3- Floor : anterior 2/3 of tongue & sublingual region. 4-Posteriorly : mouth communicates with oropharynx by oropharyngeal isthmus. . The cheek forms the lateral wall of the vestibule and is made up of the buccinator muscle, which is covered on the outside by fascia and skin and is lined by mucous membrane. The parotid duct opens at the vestibule of mouth opposite upper 2nd molar tooth. Sublingual Region : lies in the floor of mouth below tongue, contains : The frenulum of the tongue is a fold of mucous membrane in the midline connects undersurface of tongue to floor of mouth Duct of submandibular gland opens on each side of frenulum Sublingual gland is covered by m.m calledsublingual fold, which extends laterallyon both sides from lower part of frenulum, and sublingual ducts open by many aperatures on its summit. Sensory nerve supply of mucous membrane of mouth :
Roof(palate) : greater palatine & Nasopalatine nerves from Maxillary N. Floor(anterior 2/3 of tongue) :lingual N. of mandibular N. (general sensation), chorda tympani N. of facial N. (taste sensation). Cheek : buccal nerve, a branch of mandibular N. The Tongue It is a mass of striated muscle covered with mucous membrane. Its anterior 2/3 lies in mouth (oral part), while posterior 1/3 lies in pharynx (pharyngeal part). It is divided into right & left halves by a median fibrous septum. The Tongue Mucous membrane of the Upper surface of tongue (dorum of tongue) Oral &pharyngeal parts are separated by a V-shaped groove called sulcus terminalis, the apex of sulcus is marked by a pit called foramen coecum ( is an embryologic remnant ofupper end of thyroglossal duct) The mucous membrane of oral part(anterior 2/3) contains vallate papillae The mucous membrane of pharyngeal part (post.1/3) devoid of papillae, but it has a nodular irrigular surface caused by underlyinglymph nodules (lingual tonsils in submucosa). The Tongue Mucous membrane of inferior surface of the tongue : The mucosa is smooth In the midline, it is connected to the floor of mouth by a fold of m.m. called frenulum of tongue On lateral side of frenulum, deep lingual vein lies in submucosa, can be seen through the mucosa.But Lingual N. & lingual artery run at deeper plane from mucosa Lateral to vein, a serrated fold of mucosa is seen plica fimbriata Innervation of the Tongue :
Motor Nerves : All intrinsic & extrinsic muscles are supplied by hypoglossal N. EXCEPT palatoglossus is supplied by pharyngeal plexus via vagus N. Sensory Nerves : Anterior 2/3 : general sensations: by lingual N.taste sensations (excluding vallate paoillae) : by chorda tympani Posterior 1/3, including vallate papillae : general& taste sensations by glossopharyngeal N Root of tongue ( most posterior part) : internal laryngeal branches of vagus. (vagus) Blood Supply of Tongue Lingual artery : branch of external carotid artery, it supply most oftongue(the main arterial supply) Tonsillar (branch of facial) Ascending pharyngeal artery (branch of ext.carotid artery) : they supply posterior part of tongue. Veins of tongue form lingual vein ,which drains into internal jugular vein. Lymph Drainage of Tongue
Tip of tongue : drain into submental L.Ns. The remainder of anterior 2/3 of tongue : drains into submandibular + inferior deep cervical L.Ns. Posterior 1/3 of tongue : drains into superior deep cervical L.Ns. Muscles of Tongue Intrinsic muscles : They are not attached to bone They consist oflongitudinal, transverse & vertical fibers (inside the tongue) Origin : median septum & submucosa Insertion : mucous membrane Nerve supply : hypoglossal N function : Alter the shape of tongue. Extrinsic Muscles of Tongue
Extrinsic muscles : They connect tongue to styloid process & soft palate above, /and to mandible & hyoid bone below They are : Genioglossus Hyoglossus Styloglossus palatoglossus. Extrinsic Muscles of Tongue
Genioglossus : Origin : superiormental tubercle of mandible Insertion : it is fan-shaped, blends with other muscles of tongue (into tongue, & body of hyoid bone) Action : The 2 muscles : protrude tip of tongue through mouth One muscle : protrudes the tongue to opposite side. Extrinsic Muscles of Tongue
Hyoglossus : Origin : body + greater cornu of Hyoid bone Insertion : it is quadrilateral, runs upward deep to mylohyoid muscle to insert at side of post.part of tongue Action : Depress tongue and increase mouth cavityduring swallowing. Structures Superficial to Hyoglossus
Superficial relations : Mylohyoid + Styloglossus Lingual N Hypoglossal N Submandibular ganglion Deep part of submandibular gland. ligual artery (deep to hyoglossus) Extrinsic Muscles of Tongue
Styloglossus : Origin : styloid process Insertion :blends with other muscles of tongue.(whole length of side of tongue) Action : Pulls tongue upward and backward (retraction + elevation) during swallowing. It passes between superior & middle constrictors of pharynx to reach tongue. Extrinsic Muscles of Tongue
Palatoglossus : Origin : from undersurface of palatine aponeurosis (soft palate) Insertion : into the side of post.1/3 of tongue Action : pulls root of tongue upward & backward, (retraction + elevation), so narrows oropharyngeal isthmus and prevents regurgitationof food. Movements of Tongue Protrusion : genioglossus on both sides acting together. Retraction : styloglossus + hyoglossus Ms. on both sides. Depression : hyoglossus + genioglossus Ms. on both sides. Retraction & elevation of posterior 1/3 of tongue : Styloglossus +Palatoglossus,on both sides. The Palate It forms the roof of mouth.
It is divided into :hard palate anterior &soft palateposterior Hard palate : It forms anterior 2/3 of palate it is formed by palatine processes of maxillae + horizontal plates of palatine bones. -It is bounded laterally by alveolar arches and continuous behind with soft palate It forms floor of nasal cavities It is covered with muco-periosteum. Soft Palate It forms the posterior 1/3 of palate.
It is a mobile fold attached anteriorlyto the hard palate. Its posterior free end forms a conical projection in the midline called the Uvula. It lies between the naso -pharynx&oropharynx. Laterally , it is attached to side wall of pharynx. Soft palate Structures of Soft Palate
Mucous Membrane : covers its upper & lower surfaces. Palatine aponeurosis : it is a fibrous sheet in the middle, attached to posterior border of hard palate, it is the expanded tendon of Tensor veli palatini on both sides. Muscles of Soft Palate : Tensor vili palatini Levator vili palatini Palatoglossus Palatopharyngeus Musculus uvulae. Palatine aponeurosis Muscles of Soft Palate Tensor veli palatini : Origin : spine of sphenoid + auditory tube Insertion :with muscle of other side forms palatine aponeurosis which is inserted into palatine crest (posterior border of hard palate) N.supply :N. to medial perygoid from mandibular N Action :tense soft palate. Muscles of Soft Palate Levator veli palatini : Origin : Petrous part of temporal bone + auditory tube Insertion : palatine aponeurosis N.supply : pharyngeal plexus Action : elevates soft palate, shutting off nasopharynxfronoropharynx in swallowing. Palatopharyngeus: Origin : palatine aponeurosis Insertion : posterior border of thyroid cartilage+ wall of pharynx. It lies in a fold of m.m of lateral wall of pharynx, calledpalatopharyngeal arch N.supply : pharyngeal plexus Action : The 2 muscles elevate wall of pharynx + closing of pharyngealisthmusduring swallowing (communicating channel between nasal & oral parts of pharynx). Muscles of Soft Palate Palatoglossus : Origin : palatine aponeurosis Insertion : side of post.1/3 of tongue, it lies in a fold of m.m. of lateral wall of oro-pharynx, called palatoglossal arch, which lies in front of palatine tonsile N.supply : pharyngeal plexus Action : the 2 muscles pull root of tongue upward & backward, causingnarrowing of oropharyngealisthmus and prevent regurgitation of food. Musculus uvulae : Origin : posterior border of hard palate (post. Nasal spine) Insertion : m.m.of uvulae N.supply : pharyngeal plexus Action : elevates uvulae. palatoglossal & palatopharyngeal arches :are folds of mucous membranes covering the muscles of sot palte, palatoglossus &/ palatopharyngeus in the oropharynx. Oropharyngeal isthmus : it is a sphincter between mouth & oral part ofpharynx, and it is marked by the interval between 2 palatoglossal arches. Pharyngeal isthmus : it is the opening between the free end of soft palate & posterior wall of pharynx ( communication between the nasal and / oral parts of pharynx) Innervations of Soft Palate
Motor : all palatine muscles are supplied by pharyngealplexus EXCEPT tensor veli palatini (by N.to medial pterygoid from mandibular N.). Sensory : Greater & Lesser palatine Ns. ofmaxillary, NasopalatineN. of maxillary N. Blood Supply & Lymph Drainage of soft Palate :
Greater palatine from maxillary artery. Ascending palatine from facial artery. Ascending pharyngeal artery from external carotid artery. Veins of palate : end in pterygoid & tonsillar venous plexus. Lymph vessels of palate : end in deep cervical L.Ns.