Lecture 11 - ORAL CAVITY, PALATE, TONSILS AND TONGUE.pdf

THE ORAL CAVITY The oral cavity consists of two parts: The vestibule The mouth (oral cavity) proper The Vestibule The vestibule is a slitlike space between the lips and the cheeks externally, and the teeth and the gingivae internally. The roof and the floor are reflections of the mucous membrane f...

THE ORAL CAVITY The oral cavity consists of two parts: The vestibule The mouth (oral cavity) proper The Vestibule The vestibule is a slitlike space between the lips and the cheeks externally, and the teeth and the gingivae internally. The roof and the floor are reflections of the mucous membrane from the lips and the cheeks to the gums. The vestibule communicates with the exterior through the orifice of the mouth. The Vestibule Openings into the vestibule: Labial glands Parotid duct When the teeth are closed (together), the vestibule communicates with the mouth cavity through a space found between the last molars and the ramus of the mandible. The Oral Cavity Proper BOUNDARIES: Externally, by the lips and cheeks Roof is formed by the palate Floor is formed by the tongue and muscles (e.g., mylohyoid) Anterior and lateral sides are formed by the alveolar arches, the teeth and the gums Posteriorly, the oral cavity communicates with the oropharynx, which is bounded by the palatoglossal arches laterally, the epiglottis inferiorly, and the soft palate superiorly The Lips and Cheeks The lips are two muscular folds that surround and bound the entrance to the mouth. The median part of the upper lip is called the Philtrum (seen externally) Internally, each lip is connected to the corresponding gum by a median fold: frenulum Lips are covered by skin, and contain the orbicularis oris muscles and labial glands The cheeks form the lateral walls of the vestibule They have essentially the same structure as the lips with which they are continuous They contain the buccinator muscle and the buccal glands The Palate It forms the roof of the mouth and the floor of the nasal cavity. It is arched both transversely and anteroposteriorly. It consists of two parts: The hard palate: anterior 2/3 bony part The soft palate: posterior 1/3 fibromuscular, mobile part The Hard Palate The bony part of the hard palate is formed by the palatine process of the maxilla anteriorly, and the horizontal plates of the palatine bone posteriorly. The hard palate is covered by mucoperiostium which forms a median raphe terminating in front in the incisive papilla. The hard palate is ridged (transverse palatine folds) which aids in the grabbing of food. The Soft Palate It is a mobile, fibromuscular partition between the nasopharynx (above) and oropharynx (below). It is suspended from the posterior edge of the hard palate. It has a medial projection: uvula. The lateral folds of the soft palate are continuous with the uvula: Palatoglossal arch (palatoglossus muscle) Palatopharyngeal arch (palatophayngeus muscle) NOTE: The palatine tonsils are located between these two folds Muscles of the Soft Palate Musculus Uvulae m. (vagus) From the posterior nasal spine into the mucous membrane of the uvula Levator Veli Palatini m. (vagus) Tensor Veli Palatini m. (V3) Palatoglossus m. (vagus) Palatopharyngeus m. (vagus) Blood & Nerve Supply of the Soft Palate NERVE SUPPLY: BLOOD SUPPLY: Greater palatine artery from the descending palatine off the maxillary (ECA) All the muscles of the soft palate are supplied by the vagus nerve (CN X) via the pharyngeal plexus EXCEPT the tensonr veli palatini which is supplied by the mandibular division of the trigeminal nerve (CN V). Damage to the vagus nerve will cause the uvula to deviate to the opposite side. Damage to the glossopharyngeal nerve will result in ipsilateral loss of the gag reflex. The Tongue It is a muscular organ in the floor of the mouth attached to the hyoid bone, mandible, styloid process and pharynx by muscles. FUNCTIONS: 1. 2. 3. 4. Taste Mastication Swallowing Speech The Tongue The tongue has a: 1. 2. 3. 4. Tip or apex which rests against the incisor teeth Margin related to the gums and teeth on each side Inferior surface connected to the floor of the mouth by the frenulum. Root: attached to the hyoid bone and the mandible by muscles. Nerves, blood vessels and extrinsic muscles enter or leave the tongue via the root. 5. Dorsum: convex, partly in the oral cavity and oropharynx. It has a V-shaped groove: sulcus terminalis with a median foramen cecum. 1. The sulcus terminalis divides the tongue into an oral part (anterior 2/3) and a pharyngeal part (posterior 1/3) The Tongue The oral portion of the dorsum has a: Median groove Lingual papillae Filiform (conical) Fungiform (taste buds) Vallate (largest) Foliate (grooves and ridges) The pharyngeal portion of the dorsum has: Lingual tonsils The mucous membrane of the pharyngeal portion forms: Median glossoepiglottic fold Lateral glossoepiglotic folds Note: the space between the lateral and median glossoepiglottic folds is termed the epiglottic vallecula. Extrinsic Muscles of the Tongue 1. Genioglossus muscle (CN XII) 2. Hyoglossus muscle (CN XII) 3. Styloglossus muscle (CN XII) 4. Palatoglossus muscle (CN X) n Nerve Supply:All the muscles of the tongue are supplied by the hypoglossal nerve (CN XII) EXCEPT the palatoglossus which is supplied by the vagus nerve (CN X). Damage to the the hypoglossal nerve will produce ipsilateral atrophy of the tongue (“wrinkled”). When the tongue is protruded, the tip deviates towards the side of the lesion. n Blood Supply: lingual artery (ECA); lingual vein into the IJV. Sensory Innervation of the Tongue Anterior 2/3 of the tongue General Sensation = lingual nerve (V3) Taste = chorda tympani nerve (CN VII) Posterior 1/3 of the tongue General Sensation = CN IX Taste = CN IX Internal laryngeal nerve (CN X) Glossopharyngeal nerve (CN IX) (general sensation and taste) Palatoglossus (CN X) Vallate Circumvallate papillae Overlapping nerve supply Filiform papillae All other muscles of the tongue (CN XII) Lingual nerve, CN V (general sensory) Chorda tympani, CN VII (special sensory-taste) Fungiform papillae MOTOR SENSORY