Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

MouthThe gastrointestinal tract begins with the mouth (oral cavity). The lips form the anterior wall ofthe oral cavity; the cheeks (buccal mucosa) form the lateral walls; the hard and soft palates form theroof; the floor of the mouth forms the base of the cavity. Structures within the mouth are thetongue, gums (gingiva), and teeth. The entire cavity is lined with mucous membrane, but themuscularis mucosae found in other parts of the gastrointestinal tract is not present in the mouth orpharynx. The lamina propria and submueosa are, therefore, generally indistinguishable.Food enters through the lips and is broken up and crushed by the action of the tongue and theteeth. At the same time, it is mixed with the saliva produced by the salivary glands. Mastication thusbegins the first step in the digestive process.The blood supply to structures of the oral cavity is from various branches of the external carotidartery. The venous blood drains into the superficial or deep jugular veins.Ninety percent of the malignant tumors arising in the oral cavity are squamous cell carcinoma.Figure 21. ORAL CAVITYA. ABOVE THE TONGUE B. BENEATH THE TONGUE.o.._°-. ..... ..o.o..' "..... /" "'\. _,.rd _IL.I. ._"-..t...."_-_.:]..'" Subl.lnttu_t / '. _ r'Ol_,? _,li_-_-"_-_.'"_L_'.?".' '-] Ila.LJkvlltrT ELand '., _ .._FI,00r 0£ mOtAth-... _ _,./0,,£2. s( DormeLI. mmrfa©o)169