What is the Buccal Cavity? (with pictures) What is the Buccal Cavity? Originally Written By: Aniza Pourtauborde Revised By: C. Mitchell Last Modified Date: 14 December 2016 Copyright Protected: These 10 animal facts will amaze you The buccal cavity is more commonly known as the mouth, and it is the beginning of the digestive system for humans and animals alike. It starts with the lips and ends with the throat, covering the oral cavity, the tongue, and the jaw in between. Digestion is its primary function, but it also has an important role in communication. The development of speech, including words and sounds, happens here, and expressions made with the mouth are often an important part of non-verbal social cues and communications, too. Primary Sections Most medical experts talk about the mouth in terms of its two main sections, known as the vestibule and the buccal cavity proper. The vestibule is the gap between the teeth and cheeks, while the cavity proper is portion of the mouth between the teeth, which includes the tongue and throat, is roofed by the hard and soft palates, and is floored by the tongue. Both sections have important roles to play.

The vestibule receives the secretion of saliva and transfers this to the main cavity, which is where digestion first gets started. When the two parts work together a person is able to chew, break down, and swallow food and drink. Importance of the Lips At least in humans, the buccal cavity begins with the lips. The lips are made up of upper and lower parts. They are soft and fleshy folds of skin lined with mucous membranes, though the skin here is thinner than it is in most other parts of the body. It’s often more sensitive, too, and doesn’t contain hair, sweat glands, or sebaceous glands. Most people have a lot of nerve endings in their lips, and they are usually considered a tactile organ, sensitive to both touch and temperature. The main job of lips is to assist with the intake of food as it passes into the mouth. Infants and babies often need them to suck and receive milk, and even in older children and adults the lips are one of the main ways that food is drawn into the larger mouth. They also play an important role in keeping things in during chewing and early digestive breakdown. Closed lips provide a relatively tight chamber, keeping food and drink locked firmly inside.

Lips are also really important when it comes to speech and facial expressions. People depend on lip movements to make different sounds and to form words, and they can also play a role in non-verbal communication. A frown can signal displeasure, for instance, while a smile usually relates to happiness, contentedness, or even agreement. Tongue and Jaw The cavity also includes the tongue and jaw. In humans and most animals, the tongue covers the entire bottom part of the mouth, and it is one of the sensory organs of the human body. It is covered with small pimple-like bumps called taste buds, which enable it to distinguish five different flavors: sweet, bitter, salty, sour, and umami. Aside from this, the tongue helps with the chewing and swallowing of food by keeping it moist and manipulating it from one section of the cavity to the other. The tongue also influences the projection of sounds and speech. The jaw is a part of the buccal cavity that is critical to the chewing of food. It is made up of a fixed upper jawbone, known as the maxala, and a mobile lower jawbone, known as the mandible.

Together these two parts move back and forth to facilitate the tearing and chewing of food by the teeth. Similar to the tongue, movements of the jaw influence speech and communication of sounds, too. Roles Played by the Throat The throat is where the first section of the digestive system ends and the second section begins. It is found at the end of the buccal cavity proper and is made up of the pharynx, larynx , trachea, and esophagus. The throat has multiple functions, the first of which is to enable swallowing in order to control the buildup of excess secretions in the mouth such as saliva and mucus . In the digestive system, the throat moves chewed food from the mouth through the esophagus and into the stomach. Its secondary role is carried out by the larynx, which houses the vocal cords , which are crucial for the production of sounds.

Ad Buccal cavity | definition of buccal cavity by Medical dictionary Buccal cavity | definition of buccal cavity by Medical dictionary or·al ves·ti·bule [TA] that part of the mouth bounded anteriorly and laterally by the lips and the cheeks, posteriorly and medially by the teeth and/or gums, and above and below by the reflections of the mucosa from the lips and cheeks to the gums. the vestibule of the mouth, specifically the area lying between the teeth and cheeks. cavity (kav'it-e) [L. cavitas, hollow] A hollow space, such as a body organ or the hole in a tooth produced by caries. abdominal cavity The ventral cavity between the diaphragm and pelvis, containing the abdominal organs. It is lined with a serous membrane, the peritoneum, and contains the following organs: stomach with the lower portion of the esophagus, small and large intestines (except sigmoid colon and rectum), liver, gallbladder, spleen, pancreas, adrenal glands, kidneys, and ureters. It is continuous with the pelvic cavity; the two constitute the abdominopelvic cavity.

See: abdomen ; abdominal quadrants for illus. alveolar cavity The synovial cavity of a joint. CAVITIES OF THE BODY CAVITIES OF THE BODY 1. Any hollow space within the body. See: illustration 2. A hidden body space that is accessible from the outside, e.g., rectum or vagina. Referred to in “body cavity search for contraband”. 3. Derivatives of the coelom, i.e., the pericardial, peritoneal, and plural sacs. See: coelom buccal cavity The cavity of the skull, which contains the brain. dental cavity The body cavity composed of the cranial and spinal cavities. See: body cavity for illus. glenoid cavity Glenoid fossa (2). joint cavity The articular cavity or space enclosed by the synovial membrane and articular cartilages. It contains synovial fluid. Synonym: joint space laryngeal cavity The hollow inside the larynx from its inlet at the laryngopharynx to the beginning of the trachea.

It has three segments (from top to bottom): vestibule of the larynx, ventricle of the larynx, infraglottic cavity. lesser peritoneal cavity The marrow-filled space in a bone. nasal cavity One of two cavities between the floor of the cranium and the roof of the mouth, opening to the nose anteriorly and the nasopharynx posteriorly. Its lining of ciliated epithelium warms and moistens inhaled air, and traps dust and pathogens on mucus that are then swept toward the pharynx. The nasal septum (ethmoid and vomer) separates the nasal cavities, and the olfactory receptors are in the upper part of each cavity. The paranasal sinuses (frontal, maxillary, sphenoidal, and ethmoidal) open into the meatus below the conchae. The orifices of the frontal, anterior ethmoidal, and maxillary sinuses are in the middle meatus. The orifices of the posterior ethmoidal and sphenoidal sinuses are in the superior meatus.

The nasal mucosa is highly vascular; blood is supplied by the maxillary arteries from the external carotid arteries and by the ethmoidal arteries from the internal carotid arteries. oral cavity The space inside the teeth and gums that is filled by the tongue when the mouth is closed and relaxed. Synonym: buccal cavity pelvic cavity The bony hollow formed by the innominate bones, the sacrum, and the coccyx. The major pelvic cavity lies between the iliac fossae and above the iliopectineal lines. The minor pelvic cavity lies below the iliopectineal lines. See: pelvis pericardial cavity See: pericardia friction rub ; pericarditis peritoneal cavity The potential space between the parietal peritoneum, which lines the abdominal wall, and the visceral peritoneum, which forms the surface layer of the visceral organs. It contains serous fluid. pleural cavity The potential space between the parietal pleura that lines the thoracic cavity and the visceral pleura that covers the lungs. It contains serous fluid that prevents friction.

pleuroperitoneal cavity See: body cavity for illus.; coelom pulp cavity Molecular Expressions Microscopy Primer: Specialized Microscopy Techniques - Differential Interference Contrast Image Gallery - Human Cheek Epithelial Cells Differential Interference Contrast Image Gallery Human Cheek Epithelial Cells The tissue that lines the inside of the mouth is known as the basal mucosa and is composed of squamous epithelial cells. These structures, commonly thought of as cheek cells, divide approximately every 24 hours and are constantly shed from the body. Cheek cells secrete a continuous supply of mucin, the principal element of mucous. In combination with the salivary glands, the mucin maintains a moist environment in the oral cavity. A sufficient moisture content must be continually sustained in order to aid enzymes in softening food, facilitate swallowing, and initiate the process of digestion. Cheek cells are often studied in school laboratory settings because they can be easily obtained through a mouth rinse or simple swab. Yet, though the individual cells appear very simple under the microscope, they each contain the genetic make-up of the entire body. Thus, they are often used for DNA fingerprinting studies, as well as paternity testing.

Interestingly, a group of Australian researchers have recently found another use for human cheek cells. They have devised a test that utilizes cheek cells to measure an individual�s proclivity for high blood pressure. Mouth - Human Mouth Anatomy Home > Digestive System > Digestive System of the Head and Neck > Oral Cavity > Mouth Mouth Also known as the oral cavity, the mouth is the hollow cavity that allows food and air to enter the body. The mouth contains many other organs - such as the teeth, tongue, and the ducts of the salivary glands - that work together to aid in the ingestion and digestion of food. The mouth also plays a major role in the production of speech through the movements of the tongue, lips and cheeks. The mouth is a hollow cavity formed by the space between the lips, cheeks, tongue, hard and soft palates and the throat. Its external opening is located along the body’s midline inferior to the nose and superior to the chin....

Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image 2D Interactive 3D Rotate & Zoom Change Anatomical System Change View Angle Full Mouth Description [Continued from above] . . . The external opening of the mouth is usually much longer in the horizontal plane, but may be extended through the movement of the jaw to become nearly as wide in the vertical plane as well. The lips are soft, fleshy structures that form the anterior border of the external opening of the mouth. The lips are very flexible and elastic structures and contain many collagen and elastin fibers and adipose tissue covered by a thin layer of stratified squamous epithelium. The exterior of the lips is continuous with the skin and is covered by keratinized epithelium, while the inner surface is continuous with the mucous membrane of the mouth and is covered by nonkeratinized epithelium. Lateral to the lips are the cheeks, which are fleshy structures that form the sides of the mouth.

Similar to the lips, the exterior of the cheeks is covered in keratinized stratified squamous epithelium continuous with the skin and the interior is covered in nonkeratinized stratified squamous epithelium continuous with the mucous membrane. Between the epithelium layers are layers of connective tissues, nerves, and muscles. In particular the muscles of the cheeks include the buccinator, orbicularis oris and zygomaticus major, which move the lips and cheeks. The tongue forms the inferior portion of the mouth, but often moves throughout the mouth to occupy almost any region of the hollow cavity. While many people think of the tongue as a muscle, it is actually an organ made of epithelium, several skeletal muscles, nerves, and connective tissues. The tongue contains many small ridges known as papillae that help it to grip and move food around the mouth. Taste buds are hidden in valleys around some of the papillae and produce the sense of taste by detecting chemicals found in food. The tongue also helps to produce speech by altering or stopping the flow of air through the mouth to produce the sounds of many consonants. The hard and soft palates form the roof of the mouth.

On the anterior end of the mouth, the hard palate is formed by the inferior surface of the maxillae and palatine bones. These bones are covered with a thin layer of connective tissues and mucous membranes, which form small wrinkles. The roof of the mouth continues posteriorly as the soft palate, a flexible fleshy mass of tissues that ends in the uvula. The hard and soft palates work together to separate the mouth from the nasal cavity. The soft palate moves superiorly during swallowing to cover the nasopharynx of the throat, preventing food from entering the nasal cavity. The throat, or pharynx, is a funnel-shaped tube located in the posterior of the mouth. The pharynx connects the nasal cavity and mouth to the esophagus and larynx in the neck. The region of the throat behind the mouth is known as the oropharynx and forms the posterior wall of the mouth. Food in the mouth is swallowed into the oropharynx and passed on to the esophagus and the rest of the gastrointestinal tract.

Air inhaled through the mouth or nose also passes through the pharynx on its way to the larynx, and then passes through the pharynx on its way out of the body during exhalation. Inside the mouth are several structures that aid in the digestion of food. Teeth are hard structures specialized for the biting and grinding of food (known as mastication, or chewing). They form a continuous row in the bottom of the mouth surrounding the tongue on the lateral and anterior sides, as well as another nearly identical row extending from the roof of the mouth. Teeth form deep roots into the bones of the maxillae and the mandible, but grow out through the gums of the mouth to form biting surfaces. The gums, or gingiva, are soft mucous membranes surrounding the teeth, protecting the roots from decay and helping to hold the teeth in place. Finally, many salivary glands surround the mouth and release their secretion, saliva, into the mouth through many tiny ducts. Saliva helps to moisten and chemically digest food in the mouth before it is swallowed. Saliva also protects the teeth from decay by digesting and washing away tiny bits of food that become stuck to the teeth.

Prepared by Tim Taylor, Anatomy and Physiology Instructor Pigmentation Pigmentation Sabrinath B1, Sivapathasundharam B2, Gaurav Ghosh, Dhivya3 Department of Oral pathology Meenakshi Ammal Dental College, Chennai, Tamilnadu, India Sr. Lecturer 1 Professor and Head 2 Post Graduate Student 3 Abstract Change in the colour of the oral mucosa reflects the underlying health status either local or systemic. Change in color is brought about by pigmentation, and these could be physiological or pathological. Pigmentation in pathological conditions may range from a localized anomaly of limited significance to a potentially life- threatening disease. Since the dental professionals encounter a number of pigmented conditions of the oral cavity in the oral cavity it is important to have a thorough knowledge about their etiology, clinical manifestations, and their management. In the following review various pigmented lesions of the oral cavity are discussed. Key words: Melanin, Pigmented Oral Lesions INTRODUCTION Oral mucosa is deeply colored when compared to skin. Color reflects the clinical state of the mucosa; inflamed tissues are red, because of the increase in number and dilation of blood vessels, whereas normal healthy tissues are pale pink.

This coloration is the net result of many factors, one of which is pigmentation. Pigment is any coloring matter in the living tissues. Pigments are present throughout the human body including the oral cavity. Oral pigmentation is a relatively common condition that may involve any part of the oral cavity. These pigmentations may arise from intrinsic and extrinsic factors and can be physiological or pathological. If pathological, it may represent a localized anomaly of limited significance or the presentation of potentially life-threatening disease. As dental professionals encounter a number of pigmented conditions in the oral cavity it is impor tant to differentiate between normal and pathological pigmentations. Pigmentation is of two types - exogenous and endogenous. Endogenous refers to arise from within the tissues and exogenous, caused by foreign material introduced into the body. 1 The color of the oral mucosa is due to two main endogenous pigments namely- Melanin and hemoglobin. MELANOCYTES Melanin is produced by a specialized pigment producing cell called ‘Melanocyte’ situated in the epidermis and basal layer of the epithelium and are developed from the neural crest cells.

LIGHT MICROSCOPIC APPEARANCE In hematoxylin-eosin(H&E) stained sections, melanocytes appear as randomly dispersed cells wedged between the basal cells of the epidermis, having a small, dark staining nucleus and a clear cytoplasm, largely as a result of shrinkage. It is also called as low level clear cells. The average number of melanocytes in H&E stained sections is 1 of 10 cells in the basal layer. Because only 10 precent of the cells in the basal layer is melanocytes, each melanocyte supplies several keratinocytes with melanin, forming with them an Epidermal- Melanin unit. 2 SPECIFIC METHODS OF IDENTIFICATION Immunohistochemically by antibodies direc ted against S-100 and HMB-45. MELANOGENESIS Melanin formation begins by tyrosinase dependant hydroxylation of tyrosine to Dihydroxy- phenyl alanine (DOPA) and the oxidation of DOPA to dopa quinone, which is subsequently polymerized into melanin.

Melanin is synthesized within the rER of melanocytes from where it is transferred to the Golgi apparatus where it is modified and packed into as small membrane bound structures called melanosomes. These melanosomes gradually move from the cytoplasm of the melanocyte to the dendritic processes. As the content of melanin increases in the melanosomes the concentration of melanogenic enzyme decreases. The development of the melanosomes takes place in four stages. Stage I melanosomes are round, measure about 0. 3 mm in diameter and possess very intense enzyme ac tivity concentrated along filaments. They contain no melanin. Stage II melanosomes are ellipsoid and measure approximately 0. 5 mm in length, as do the melanosomes of stage III and IV. They contain longitudinal filaments that are cross-linked with one another. Enzyme activity is present both on the enveloping membrane and on the filaments. Melanin deposition on the cross-linked filaments begins at this stage. Stage III melanosomes have only little tyrosinase activity but show continued melanin deposition, partially through non enzymatic polymerization. Stage IV melanosomes no longer possess tyrosinase activity.

Melanin, which is formed entirely by nonenzymatic polymerization, fills the entire organelle and obscures its internal structure. 2 MELANIN TRANSFER Formed melanin is transferred to the keratinocytes takes place by exocytosis, cytophagocytosis, plasma membrane fusion or transfer by membrane vesicles. PIGMENTED ORAL LESIONS Malignant Melanoma PIGMENTATION DUE TO DEVELOPMENTAL DISORDERS Pigmented cellular nevus Nevus is also called birth mark. Pigmented cellular nevus is benign proliferation of the nevus cells either in the epithelium or connective tissue and is categorized as hamartoma or developmental malformation. Melanocytic nevi can be congenital or acquired. Congenital melanocytic nevi are classified into two types according to their size: Giant congenital melanocytic nevi (also called as the ‘Garment nevus’, ‘Bathing trunk nevus’ or ‘Giant hairy nevus’) are greater than 20cm in diameter and Small congenital nevi, which are usually less than 1. 5 cm in their greatest dimension.

3 Acquired melanocytic nevus, commonly referred to as the ‘mole’ is seen occurring frequently on the skin. Intra orally, they occur on the hard palate. Histologically, they are classied as junctional, intradermal or intramucosal, and compound nevi based on the location of the nevus cells. 4 Junctional nevi are at and dark brown in colour because the nevus cells proliferate at the tips of the rete pegs close to the surface. Intramucosal and compound nevi are typically light brown, dome-shaped lesions. Blue nevi are characterized by proliferation of dermal melanocytes within the deep connective tissue at some distance from the surface epithelium, which accounts for the blue colour. Although transformation of oral pigmented nevi to melanoma has not been well documented, it is believed that nevi represent precursor lesions to oral mucosal melanoma. It is therefore recommended that these lesions be excised and submitted for histopathologic examination. 5 Labial Melanotic Macule (labial lentigo) The labial melanotic macule occurs in the lips, more commonly in the lower lip.

It shows a predilection for occurrence in women but can also occur in males. 6 The lesion appears as a solitary well- defined, oval, brownish-black, flat patch ranging from 1 to 8mm in diameter. Exposure to UV radiation is thought to be the most important etiologic factor in the pathogenesis of the lesion 7 (Fig 1). Oral Melanotic Macule Macule is a non elevated discoloration. The oral melanotic macule is a flat, brown mucosal discoloration produced by a focal increase in melanin deposition along with an increase in the number of melanocytes. They may appear as solitary or multiple macules and can involve the gingiva, lip, palate, buccal mucosa, and alveolar ridge. Microscopically, the melanin deposition is seen mainly in the basal cell layers. 4 Polyostotic Fibrous Dysplasia Fibrous dysplasia principally affects the bone wherein bone is replaced by a dysplastic fibrous tissue. It is classified according to the number of bones affected as monostotic (single bone) and polyostotic (multiple bones).

The polyostotic form is associated sometimes with syndromes like Jaffe- Lichtenstein and Mc Cune Albright, where Café au lait pigmentation is a common clinical presentation. 8 Neurofibromatosis Neurofibromatosis (NF) is an autosomal dominant disorder with a high degree of penetrance and variable expressivity. Two sub types are known Neurofibromatosis 1 (NF1) and Neurofibromatosis 2 (NF2). NF 1 is commonly associated with Café au lait pigmentation of the skin. They appear as oval-shaped light brown patches greater than 0. 5cm in diameter. It is also known as Von Recklinghausen’s disease of the skin. 9 Peutz-Jeghers Syndrome Peutz-Jeghers syndrome is an autosomal dominant disorder with a high degree of penetrance and is commonly associated with benign intestinal polyposis, most commonly in the jejunum and ileum. 10 The typical presentation is irregular pigmented patches of dark brown or black up to five millimeters in diameter on the buccal mucosa and perioral region. The lesions may also be found on the gingiva and palate.

11 Physiologic (Racial) Pigmentation: Physiologic pigmentation occurs due to an increased melanocytic activity rather than an increase in the number of melanocytes. The colour ranges from light to dar k brown. The attached gingiva is the most common intraoral site of such pigmentation. It appears as a bilateral, well demarcated, ribbon-like, dark brown band. The marginal gingiva is usually not affected. The buccal mucosa, hard palate, lips and tongue may also be affected. This pigmentation is asymptomatic which requires no treatment. 5 (Fig 2) PIGMENTATION DUE TO SPECIFIC AGENTS Amalgam Tattoo and Other Foreign-Body Pigmentation Amalgam tattoo is one of the most common causes of intraoral pigmentation. Amalgam tattoos are twice as common as melanotic macules and ten times as common as oral nevi. 1 2 The gingiva and alveolar mucosa are most commonly involved, it may also occur in the floor of the mouth and buccal mucosa. It presents clinically as a localized, blue–grey lesion. In periapical view radiographs the amalgam particles are usually seen as radiopaque granules.

In case of doubt, a biopsy should be performed to demonstrate the presence of amalgam particles in the connective tissue. Sometimes, graphite may be incorporated into the oral mucosa through accidental injury with a graphite pencil. This type of lesion occurs frequently in children especially in the anterior palate. Clinically, it appears as an irregular grey to black macule. It is mandatory to differentiate this lesion from melanoma since it commonly occurs on the palate. 5 Smoker’s Melanosis Smoking may cause oral pigmentation with increased production of melanin. It may provide a biologic defence against the noxious agents present in tobacco smoke. Smoker’s melanosis occurs in up to 21. 5 percent of smokers. The intensity of the pigmentation is related to the duration and amount of smoking. Women are more commonly affected than men, which suggest a possible synergistic effect between the female sex hormones and smoking. The brown–black lesions most often involve the anterior labial gingiva followed by the buccal mucosa. Smoker’s melanosis usually disappears within three years of smoking cessation. Biopsy should be performed if there is surface elevation or increased pigment intensity or if the pigmentation is in an unexpected site.

1 3 (Fig 3) Heavy Metal Pigmentation Increased levels of heavy metals (e. g., lead, bismuth, mercury, silver, arsenic and gold) in the blood are commonly known to cause oral mucosal discoloration. In adults, the most common cause is occupational exposure to heavy metal vapors. Treatment with drugs containing heavy metals, such as arsenicals for syphilis, was a common cause in the past. In children, exposure to lead-contaminated water or paint and mercury or silver-containing drugs represents a common cause. For example, pigmentation due to lead poisoning appears as a blue–black line along the marginal gingiva known as Burtonian line 5 . Drug-Induced Pigmentation Oral mucosal pigmentation may occur as a side effec t of drug therapy. Drugs commonly associated with oral mucosal pigmentation include Zidovudine, estrogen, cyclophosphamide, ketaconazole, chloroquine and minoc ycline. 14 This pigmentation occurs due to synthesis of melanin under the influence of the drug, deposits of the drug or one of its metabolites.

These drugs commonly cause pigmentation of the hard palate where it commonly produces a blue-grey or blue-black discoloration. Laboratory studies have shown that these drugs may produce a direct stimulatory effect on the melanocytes. Minocycline, a synthetic tetracycline causes pigmentation of the alveolar bone, which can be seen through the thin overlying oral mucosa as a grey discolouration. 15 Post inflammatory Pigmentation Mucosal diseases in particular lichen planus can cause mucosal pigmentation which is clinically seen as multiple brown–black-pigmented areas adjacent to reticular or erosive lesions of lichen planus. Histologically, there is increased production of melanin by the melanocytes and accumulation of melanin- laden macrophages in the superficial connective tissue. 10 PIGMENTATION DUE TO ENDOCRINE DISORDERS Addison’s Disease Addison’s disease, or primary hypoadrenalism, is due to progressive bilateral destruction of the adrenal cortex by autoimmune disease, infection or malignancy. The increased production of ACTH induces melanocyte-stimulating hormone, which results in diffuse pigmentation of the skin and oral mucosa.

Oral involvement presents as diffuse brown patches which affects the gingiva, buccal mucosa, palate and tongue. Cushing’s syndrome, acromegaly and hyperthyroidism also show pigmentation similar to Addison’s disease. 10 COLOURED LESIONS OF VASCULAR ORIGIN Hemangioma and Vascular Malformation Hemangioma is a benign proliferation of the endothelial cells, endothelial lined vessels or spaces. Vascular malformation is a structural anomaly of blood vessels without endothelial proliferation. Vascular malformation occurs during birth and regresses as the patient ages. 8 The lesion may be at or slightly raised and varies in color from red to bluish purple depending on the type of vessels involved (capillaries, veins or arteries) and the depth of the lesion in the tissues. The most commonly affec ted site is the lip, although any region in the oral cavity may be involved. 4 Varix and Thrombus Varices are abnormally dilated veins. The most common intraoral location is the ventral surface of the tongue, where varices appear as multiple bluish purple, irregular, soft elevations that blanch on pressure.

If the varix contains a thrombus, it presents as a bluish purple nodule that does not blanch on pressure. Thrombi are more common on the lower lip and buccal mucosa. Hemorrhagic Lesions Petechiae, purpurae and ecchymoses are sub mucosal hemorrhages. They all have the same mechanism of presentation and differ only in size. Telangiectasia is a small, red, macular lesion that is composed of dilated capillaries under the epithelium. Petechial and ecchymotic patches are usually seen at the junction of hard and soft palate. 10 (Fig 4) Kaposi’s Sarcoma Kaposi’s sarcoma (KS) is a multifocal vascular malignancy seen predominantly in HIV-infected individuals. The development of this tumor is considered diagnostic of AIDS progression. A human herpes virus (HHV-8, also called Kaposi’s sarcoma- associated herpes virus) has been implicated as the cause. 1 6 KS in the oral mucosa most commonly affects the hard palate, gingiva and tongue. Early lesions appear as at or slightly elevated brown to purple lesions that are often bilateral.

Advanced lesions appear as dark red to purple plaques or nodules that may exhibit ulceration, bleeding and necrosis. Definitive diagnosis requires biopsy, which shows a proliferation of spindle-shaped cells surrounding poorly formed vascular spaces or slits with numerous extravasated red blood cells. 5 PIGMENTATION DUE TO SUN EXPOSURE Actinic Lentigo (Solar lentigo) Actinic lentigo is a benign, brown macule that occurs due to chronic ultra violet damage to the skin. It commonly occurs on the dorsum of the hands and face 4 . (Fig 5) Melasma It is an acquired, symmetric hyperpigmentation of the sun exposed skin of face and neck. It is seen on the upper lip 4 . PIGMENTATION DUE TO HYPERPLASTIC PROCESS Lentigo simplex It is a benign cutaneous melanocytic hyperplasia of unknown cause. It usually occurs on skin not exposed to sunlight. Oral lesions are also seen. The lesions appear as sharply demarcated macule less than five millimeters in diameter. Oral Melanoacanthoma Oral melanoacanthoma is an uncommon benign pigmented reactive lesion of the oral mucosa with no malignant potential.

The buccal mucosa is the most common site of occurrence 17 . Clinically, the lesion appears at or slightly raised and is hyperpigmented, the colour ranging from dar k brown to black. It is characterized by proliferation of dendritic melanocytes scattered throughout the thickness of an acanthotic and hyperkeratotic surface epithelium. This lesion, in contrast to most of the benign pigmented lesions has a tendenc y to enlarge rapidly, which raises the possibility of a malignant process in the clinical differential diagnosis 18 . PIGMENTED MALIGNANT LESION Malignant melanoma Melanoma is a malignant neoplasm of the epidermal melanocytes. Certain lesions are said to be precursor lesions of melanoma, including the common acquired nevus, dysplastic nevus, congenital nevus and cellular blue nevus 19 . Criteria for clinical diagnosis of melanoma ( ABCDE-rule ) Asymmetry- in which one half does not match the other half Border irregularity- with blurred, notched or ragged edges Colour irregularity- pigmentation is not uniform. Brown, black, tan, red, white and blue can all appear in a melanoma.

Diameter- greater than 6 mm. Growth in itself is also a sign. Elevtaion- a raised surface can also be a sign. Types of melanoma: Mucosal lentiginous melanoma 20 . Of these, Acral lentiginous and Mucosal lentiginous melanoma commonly occur in the oral cavity. Most frequently seen in the hard palate, where it appears as a brown to black macule with irregular borders 21 . (Fig 6) CONCLUSION It is clear that oral pigmentation is a relatively common condition that can occur in any portion of the oral cavity and arises from intrinsic and extrinsic factors and can be physiological or pathological. The dentist may be the first health care professional to observe the colour changes in the oral cavity which may be a manifestation of the underlying pathological process. 1. Antonio Nanci. Tencate's Oral Histology. 7th edition. Elsevier publications; 2008. 2. David Elder. Lever's Histopathology of the skin, 8th edition. Lipincott-Raven publishers; 1997 3. Z.Tannous, M.Mihm Jr, A.Sober, L.Duncan.

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Oral surg Oral med Oral Pathol Oral Radiol Endod 1997; 83 :672-679 Anatomy and physiology of the oral cavity - Canadian Cancer Society A- | A | A+ Anatomy and physiology of the oral cavity The oral cavity (mouth) includes the lips, cheeks, palate (roof of the mouth), floor of the mouth and the part of the tongue in the mouth (oral tongue). A mucous membrane lines and protects the inside of the mouth. The structures in the oral cavity play an important role in speech, taste and the first steps of digestion. Note: The lining of the lips and cheeks (buccal mucosa) are not shown. Structure The oral cavity begins at the border between the skin and the lips (vermillion border). The roof of the mouth is formed by the hard palate. The oral cavity leads into the oropharynx, which includes the soft palate, the back of the tongue and the tonsils. The inner surface of the cheeks forms the sides of the oral cavity. The lowest part of the oral cavity is the floor of the mouth, which is covered by the tongue.

The oral cavity can be divided into specific areas, including: lips labial mucosa (inner lining of the lips) commissure of lips (where the upper and lower lips meet at the corner of the mouth) vestibule (a space bounded by the teeth and gums on the inside and the mucosal surface of the lips and cheeks on the outside) oral tongue (the front two-thirds of the tongue) floor of the mouth buccal mucosa (the inner lining of cheeks) gingiva (gums) retromolar trigone (the area just behind the back molars in the lower jaw) hard palate (the bony part at the front of the roof of the mouth) teeth upper jaw (maxilla) Function The function of the oral cavity and its structures is to begin the process of digestion. The oral cavity receives food, chews and mixes it with saliva and then begins the swallowing process. The taste buds on the tongue provide the different sensations of taste. The oral cavity plays an important role in speech. The mouth is also used for breathing, drinking, facial expressions and social interactions (such as kissing).

Question: In the human body, the buccal cavity is commonly known as what?
Answer: The mouth