By Dr. Muaid I Aziz MBChB FICMSOtorhinolaryngology –head & neck surgeon
Oral cavity Pharynx larynx
Its an oval shaped cavity extend from the lips to the palatoglossal arches
The entire oral cavity is lined with mucous membrane tissue. The oral cavity consists of the following two areas:1. The vestibule is the space between the teeth and the inner mucosal lining of the lips and checks.2. The oral cavity proper is the space contained within the upper and lower dental arches.
Bones that contribute to the skeletal framework of the oral cavity or are related to the anatomy of structures in the oral cavity include: the paired maxillae & palatine. the unpaired mandible, sphenoid and hyoid bone.
Laterally : lips & gum Medially : upper& lower rows of teeth Posteriorly : retromolar area
lips like the cheeks , the lips are covered externally by skin & internally by mucous membrane ( labial mucosa). the lips have a muscular skeleton , the orbicularis oris muscle . the red zone of the lip ( the vermilion )which devoid of hair& has a rich capillary blood supply-hence the color.
Gingivae (gums): are firmly attached to the alveolar margins of the jaws & surround the necks of the teeth. They consist of dense vascular fibrous tissue covered by epithelium . the change from alveolar mucosa to gingival mucosa is marked by an abrupt change of color , from shiny alveolar to pink opaque gingival.
Permanent dentition are as follows 2 midline incisors I canine 2 premolars 3 molars(8 each half,32 in all) while the deciduous dentition 5 each half 20 in all 2 incisors I canine 2 molars
the part which project into the mouth is the crown which is covered by enamel . the part held in the jaw is the root which is covered by cementum( calcified tissue not bone)., the junction between the 2 parts is the cervical margin or neck, The bulk of a tooth consist of dentine( a hard avascular calcified tissue penetrated by minute canals((dentinal tubules)) ) inside the dentine is the pulp cavity which filled by dental pulp (loose connective tissue with nerves, blood vessels & lymphatics ,all which get access to the pulp through apical foramina . the tooth is slung in its bony socket by the periodontal ligament which shows as a clear interval between tooth &bone shadows in a
It’s the mucosal surface behind the 3rd molar tooth up to the maxillary tuberosity . there the mucosa overlies the anterior border of the ascending ramus of mandible , separated from it by pterygomandibular raphe ,where the buccinator&sup. Constrictor muscles decussate
Cheeks : are covered externally by skin &internally by mucous membrane(buccal mucosa)& have a muscular skeleton ,the buccinators,. Internally ,the pink mucosa of the cheek adhere firmly to the buccinators muscle
few structural landmarks are visible. The parotid duct opened as small papilla opposite the maxillary 2nd molar tooth a whitish line (linea alba) may be seen at a position related to the occlusal plane of the teeth which is as a result of continuous mild trauma during biting . yellow patches ( Fordyce spots )representing ectopic sebaceous glands , fold of mucosa covering pterygomandibular raphe seen on opening of the mouth widely behind the molar teeth .
The skeleton of the hard palate is formed by the palatine process of maxilla horizontal plates of palatine bones ,
oral mucosa tightly adhered to underlying periosteum. In its more lateral regions it also possesses a submucosa where the main neurovascular bundles lie. The periphery of the hard palate surrounding the necks of the teeth is termed gingiva & a midline palatal raphe extending anteroposteriorly in the midline is devoid of submucosa where anteriorly behind the incisors a small prominence ,incisive papilla , which covers the incisive fossa at the oral opening of the incisive canal , radiating outwards from the palatal raphe are irregular transverse ridges or ruge . its nasal surface covered with respiratory epithelium while oral mucosa is keratinized epithelium
Soft palate: its as mobile flap suspended from the back of the hard palate , sloping down between the oral & nasal part of the nasopharynx. it distinguished from hard palate by its change in color to be darker red with a yellowish tint. A median conical process , the uvula , projects downwards from its posterior border. It contains an aponeurosis ,muscular tissue , vessels, nerves ,lymphoid tissue & mucous glands with some taste buds situated on its oral surface. The aponeurosis is thick in the anterior 2/3 of the soft palate & thin as goes backwards , all palatine muscles attached to the aponeurosis. A thin fibrous palatine aponeurosis is attached to the posterior border of the hard palate which represent the expanded tendon of tensor veli palatine muscles & provides the fibrous skeleton of the soft palate that support the palatine musculature.
The soft palate continues posteriorly from the hard palate &acts as a valve that can be: depressed to help close the oropharyngeal isthmus. elevated to separate the nasopharynx from the oropharynx.
Five muscles on each side contribute to the formation and movement of the soft palate. tensor veli palatini m. levator veli palatini m. palatoglossus m. Palatopharyngeus m. musculus uvulae All muscles of the soft palate are innervated by the vagus nerve [X] except for tensor veli palatini, which is innervated by the mandibular nerve [V3] (via the nerve to medial pterygoid).
Floor of the mouth a small horseshoe-shaped region beneath the tongue near the base of the tongue in the midline , a fold of tissue called the lingual frenlum. sublingual papilla submandibular salivary ducts open into the mouth at this papilla . on either side of the sublingual papilla are the sublingual folds, beneath which lie the submandibular ducts & sublingual glands. The muscle forming the floor of the mouth is mylohyoid muscle & genohyoid m.
It’s a bulky muscular organ It has 2 parts ( oral & pharyngeal ) has dorsal ,ventral surfaces, root & apex Oral part triangular in shape demarcated from pharyngeal part by V (shaped sulcus terminalis) Apex facing incisor tooth Root attached to the mandible & hyoid bone
PAPILLAE The superior surface of the oral part of the tongue is covered by hundreds of papillae: filiform papillae fungiform papillae vallate papillae foliate papillae All except the filiform papillae have taste buds on their surfaces. PHARYNGEAL SURFACE there are no papillea on pharyngeal surface. the mucosa is irregular in contour bec. of the many small nodules of lymphoid tissue in the submucosa (lingual tonsil).
Actions:Intrinsic m.: are 4 groups , superior & inferior longitudinal , the transverse & the vertical muscles*alter shape of tongue.Extrinsic m.:*These muscles protrude,retract,depress, and elevate the tongue.
The extrinsic m composed of 4 pairs of muscles ( genioglossus, hyoglossus, styloglossus, & palatoglossus ) narrow the oropharyngeal isthmusaction is to pullthe tongue Moving from side to sideupwards &backwards it depress the tongue
Lymphatic drainage of the oral cavity: The principal sites of drainage of lymphatic vessels from orodental tissues are the submental submandibular jugulodiagastric & jugulo-omohyoidLN. The cheek, upper lip& lateral parts of lower lip drains to the submandibular LN while the central part of the lower lip drains to the submental LN. Teeth usually drains directly into submandibular LN on the same side while the mandibular incisor drains into submental LN. occasionally , lymph from molars may pass directly into jugulodiagastric group of the nodes. The lingual & palatal gingivae drains into the jugulodiagastric group of the nodes either directly or indirectly through submandinlar nodes .
A significant feature of the tongues lymph drainage which is through floor of the mouth or pharyngeal wall, is that lymph from one side specially of the posterior part may reach nodes of both sides ( in contrast to the blood supply which remains unilateral ). The tip may drain to submental nodes or directly to the deep cervical LN . marginal lymphatics from the rest of the anterior part drains into ipsilateral submandibular & then to the deep cervical LN but sometimes directly to the deep cervical LN. central lymphatics from anterior part descend between the geniglossi & drain to the deep cervical LN of either side. The posterior part drain directly & frequently bilaterally to the deep cervical LN. the deep cervical LN involved are the jugulodiagastric & jugulomohyoid nodes . all lymph from the tongue is believed to eventually drain through the jugulo- omohyoid node before reaching the thoracic doctor the right lymphatic duct.
Oral mucosa : the lining of the mouth , the oral mucosa is continuous with the skin at the vermilion of the lip & with the pharyngeal mucosa at the oropharyngeal isthmus . it can be classified into: masticatory mucosa covers the gingivae (gums) & a hard palate . its epithelium is keratinized , pink in color & a submucosa is absent from the gingivae & the midline palatine raphae , but present on the rest of the palate & its firmly bound to the underlying bone or to the neck of the teeth . Lining mucosa covers internal surface of the lips& cheeks ,floor of the mouth, soft palate , ventral surface of the tongue & the alveolar process excluding gingivae . its red color which have non-keratinized squamous epithelium overlying a loosely fibrous & elastic lamina propria& the submucosa contains some fat deposits & collections of minor mucous glands. Gustatory mucosa covers the anterior 2/3 of the dorsum of the tongue . the vermilion ( red zone) of the lip, the epithelium that attaches the tooth to the gingiva( has features of both lining & masticatory mucosa).