Oral Cavity Anatomy PDF

Oral cavity BY SUNDUS PARI Oral cavity The oral cavity extends from the lips to the oropharyngeal isthmus. It has 3 major functions i. Digestion ii. Communication iii. breathing Structures Lips Teeth Tongue Palate Salivary glands Uvula tonsils Lips The lips are two fle...

Oral cavity BY SUNDUS PARI Oral cavity The oral cavity extends from the lips to the oropharyngeal isthmus. It has 3 major functions i. Digestion ii. Communication iii. breathing Structures Lips Teeth Tongue Palate Salivary glands Uvula tonsils Lips The lips are two fleshy folds that surround the oral orifice. Covered on the outside by skin and inside by muscous membrane. Lips form the opening of the oral cavity and are essential for functions such as speech, eating, and facial expressions. Division It is divided into two subdivisions i. Vestibule ii. Oral cavity proper Vestibule It is a horse shoe shaped structure situated anteriorly. It is the space between the lips/cheek and the gums/teeth. The lateral wall of vestibule is formed by the cheek which is made up of buccinator muscle & is lined with mucous membrane. A small papilla on the mucosa opposite the upper 2nd molar teeth marks the opening of the parotid gland. Oral cavity proper It is the cavity within the alveolar margins of the maxillae and the mandible. it has a a. Roof b. Floor cheek forms its lateral borders. Roof of the mouth The roof of the mouth is formed by the hard & soft palate. The hard palate lies anteriorly it is a bony plate that separates the nasal cavity from the oral cavity. The soft palate lies posteriorly and is muscular structure.it acts as a valve that can lower and close the oropharyngeal isthmus and elevates to separate the oropharynx and the nasopharynx. Floor of the mouth It is formed by the mylohyoid muscle the anterior 2/3rd of tongue lies on the floor. In the midline a fold of mucous membrane called the frenulum of the tongue which connects the tongue to the floor of the mouth. The submandibular and sublingual glands are present here. Nervous supply Roof: by greater palatine and nasopalatine nerves. Floor: by lingual nerve. Cheek: by buccal nerve. Branches of facial nerve supply motor innervation to muscles of cheek and the lips. Teeth There are 32 permanent teeth 4 incisors 2 canines 4 premolars 6 molars in each jaw Tongue Mass of straited muscles covered with mucous membrane. Divided into right and left halves by median fibrous septum. It has 3 parts i. Oral anterior 2/3rd ii. Pharyngeal posterior 1/3rd iii. Root (base) Surafces It has 2 surfaces a. Dorsal surface b. Ventral surface Dorsal surface Divided into anterior 2/3rd and posterior 1/3rd by a V- shaped sulcus terminalis. The apex of the sulcus faces backward and is marked by a pit called the foramen cecum. Dorsal cont.. Anterior 2/3rd : rough, having 3 types of papillae: Fungiform Filiform Vallate Dorsal cont.. Posterior 1/3rd : No papillae but shows nodular surface because of underlying lymphatic nodules, the lingual tonsils. Ventral surface Smooth In the midline anteriorly, a mucosal fold, frenulum connects the tongue with the floor of the mouth. Muscles of the tongue The muscles of the tongue are divided into two types i. Intrinsic muscles ii. Extrinsic muscles Intrinsic muscles Confined to the tongue No bony attachments Consists of o Transverse o Longitudinal o Vertical fibers Action: alter the shape of the tongue Extrinsic muscles It is attached to surrounding bones ( mandible, hyoid bone, styloid bones) the soft palate. Include: palatoglossus, genioglossus, hyoglossus, styloglossus Action: helps in movements of the tongue. Movements Protrusion: genioglossus on both sides sides acting together. Retraction: styloglossus & hyoglossus on both sides acting together Depression: hyoglossus & genioglossus on both sides acting together. Elevation: styloglossus & palatoglossus acting together on both sides. Arterial and nerve supply Arterial supply is by the lingual artery, tonsillar branch of facial artery. Vein drains into internal jugular nerve. Sensory innervation: Anterior 2/3rd : lingual branch of trigeminal nerve & chorda tympani branch of facial nerve ( taste). Posterior 1/3rd : glossopharyngeal nerve ( general sensation). Motor nerve supply Intrinsic muscles: hypoglossal nerve Extrinsic muscles: all supplied by hypoglossus nerve except palatoglossus. Palatoglossus is supplied by the pharyngeal plexus. Function Taste Speech production Sucking Chewing swallowing Clinical importance Tongue tie ( ankyloglossia) due to small frenulum. Lesion of hypoglossal nerve: the protruded tongue deviates towards the side of the lesion. The tongue is wrinkled and atrophied. Palate Lies in the roof of the oral cavity. Has 2 parts Hard Palate ( bony) anteriorly Soft palate (muscular) posteriorly Hard palate It is immobile bony structure. Lies in the roof of the oral cavity Forms the floor of the nasal cavity Formed by palatine processes of maxillae horizontal plates of palatine bones Posteriorly continuous with the soft palate Foramina There are three main foramina/canals in the hard palate: Incisive canal – located in the anterior midline, transmits the nasopalatine nerve and descending palatine artery. Greater palatine foramen – located medial to the third molar tooth, transmits the greater palatine nerve and vessels. Lesser palatine foramina – located in the pyramidal process of the palatine bone, transmits the lesser palatine nerve. Soft palate Attached to the posterior part of the hard palate Covered on its upper and lower surfaces by mucous membrane. Composed of: Muscle fibers Glands Blood vessels nerves  Anteriorly, it is continuous with the hard palate and with the palatine aponeurosis. The posterior border of the soft palate is free (i.e. not connected to any structure), and has a central process that hangs from the midline – the uvula. The soft palate also forms the roof of the fauces; an area connecting the oral cavity and the pharynx.  Two arches bind the palate to the tongue and pharynx; the palatoglossal arches anteriorly and the palatopharyngeal arches posteriorly. Between these two arches lie the palatine tonsils, which reside in the tonsillar fossae of the oropharynx Muscles Tensor veli palatini: origin: spine of sphenoid, auditory tube insertion: forms palatine aponeuroses action: tenses soft palate Levator veli palatini: origin: petrous temporal bone, auditory tube insertion: palatine aponeurosis action: raises soft palate  Musculus ovulae: origin: posterior border of the hard palate insertion: mucosa of uvula action: elevates uvula Palatoglossus: origin: palatine aponeurosis insertion: side of tongue action: pulls root of tongue upward, narrowing oropharyngeal isthmus  Palatopharyngeus: origin: palatine aponeurosis insertion: post. Border of thyroid cartilage action: elevates wall of the pharynx Palatine aponeurosis A fibrous sheet Attached to the posterior border of the hard palate. It is the expanded tendon of the tensor veli palatine muscle. Nerve supply Mostly by the maxillary nerve through its branches o greater palatine nerve o lesser palatine nerve o nasopalatine nerve Glossopharyngeal nerve supplies the region of the soft palate. Blood supply Branches of maxillary artery: Greater palatine Lesser palatine Sphenopalatine Ascending palatine, branch of the facial artery. Clinical importance Cleft palate unilateral bilateral mixed Paralysis of soft palate occurs due to which the pharyngeal isthmus cannot be closed during swallowing and speech.