The Oral Cavity and the Teeth PDF

THE ORAL CAVITY AND THE TEETH ORAL CAVITY (CAVUM ORIS) Is lined with an uninterrupted mucous membrane which is continuous with the skin near the vermillion border of the lips and with the pharyngeal mucosa in the region of the soft palate and anterior pillars of the fauces. Epi...

THE ORAL CAVITY AND THE TEETH ORAL CAVITY (CAVUM ORIS) Is lined with an uninterrupted mucous membrane which is continuous with the skin near the vermillion border of the lips and with the pharyngeal mucosa in the region of the soft palate and anterior pillars of the fauces. Epithelium of the oral mucosa originates partly from the Ectoderm: lips, vestibules, gingiva, cheeks, palate and floor of the mouth Endoderm: tongue The beginning of the digestive System. Is divided by the alveolar processes and the dental arches of the maxilla and mandible into 2 spaces: 1. Vestibule (Vestibulum Oris) –smaller space, “the area outside the teeth” Facially (labially and buccally) – mucosa Labially – mucosa of the lips Bucally –mucosa of the cheeks Orally – alveolar mucosa, gingiva and facial surfaces of the teeth  Oral Cavity Proper (Cavum Oris Proprium) - Larger space A. Anteriorly and Laterally - Oral (palatal and lingual) surfaces of teeth and gingiva B. Cranially - mucosa of the hard palate and soft palate C. Caudally - mucosa of the tongue and floor of the mouth D. Posteriolateraly - anterior pillar of the fauces and tonsils Para-Oral Tissues Lips Cheeks Teeth and its supporting structures Hard and Soft Palate Tongue Floor of the Mouth Tonsils Salivary Glands TONGUE Is a muscular body with variable mobility 3 regions Tip (Apex linguae) Body (Corpus linguae) Base (Radix linguae) - posterior 2/3 of the tongue. Tip and body located on the anterior 2/3 of the tongue and lies within the oral cavity proper. The base – the posterior 1/3 of the tongue, lies in the pharynx.  Sulcus Terminalis (Terminal Sulcus) – a V-shaped line where the body and base joins. Foraemen Cecum – marks the foramen orifice of the thyroglossal duct. Median Sulcus – divides the long axis of the tongue into equal halves and has a complex papillary characteristics. Specialized Mucosa – mucosa of the dorsum of the tongue Thick parakeratinized to keratinized epithelium and mediates sensations of touch, temperature and taste. Lingual Tonsils – oval cryptolymphatic units found at the mucosa of the base of the tongue. The bulk of the tongue is composed of striated muscle and covered on all sides by fascia linguae and mucosa.  Nerve Supply Nerve for Taste buds of the anterior 2/3 of the Tongue – Chorda Tympani branch of the 7th cranial nerve Anterior 2/3 of the Tongue – Lingual branch of the Mandibular Nerve Posterior 1/3 of the Tongue – Glossopharyngeal nerve Arterial Supply Anterior 2/3 – Deep lingual artery (dorsal and ventral) Posterior 1/3 – Dorsal lingual artery, to base of tongue, about posterior third Lingual Sulcus – Sublingual artery  4 Types of Papillae (Epithelial Structures) 1. Filiform Papillae - Slender, thread-like keratinized extensions of the surface epithelial cells each with a core of connective tissue. Covers the entire anterior of the Tongue and give it a velvety appearance. Most numerous papillae. These are hair like or thread like in appearance projecting out from the dorsal surface of the tongue. - Are the carriers and mediators for the sense of touch. Their role is to provide a rough surface that aids in chewing via their keratinized, stratified squamous epithelia. - It provides a tactile sensation or ability to know that there is something on the tongue. They do not have taste bud, no Taste function. Spatial perception like transmitting pressure and tensions. Function is due to the presence of myelinated nerve fibers that reach into the filiform papillae. 3 types of Nerve Endings: 1. Free Nerve Endings 2. Complex End Organs 3. Epithelial Nerve Endings Hairy Tongue – sometimes the epithelium on these papillae grows very long and traps food and pigments originating from oral bacteria and food in between them. Glossitis –the epithelium of these papillae are lost and the surface of the epithelium becomes very smooth. Occurs in a number of disease process like Vitamin Deficiency. Fungiform Papillae Smooth, round or mushroom structure with the cap larger than the stalk that appear red because of their highly vascular connective tissue core. Taste buds are normally present in the epithelium on the superior surface. More than 1600. Found at: Tip of the Tongue – mediate the taste sensation of sweetness Edge of the Tongue – saltiness These are fungus-like papillae having dome shaped structures projecting above the surface of the tongue. The Fungiform papillae are located in between the Filiform papillae but mostly seen in the tip and sides of the tongue.  is a thin non keratinized stratified squamous epithelium giving the reddish color to the papillae. The supporting connective tissue shows collagen fibers, fibroblasts and blood vessels. The fungiform papillae are innervated by the seventh cranial nerve via the sub-mandibular ganglion, chorda tympani and geniculate ganglion ascending to the solitary nucleus in the brain stem. Foliate Papillae Perceives sour sensation. Are 8-15 bilateral ridges of mucosa located at the posterior edge of the tongue. Rows of wart-like structures. In elderly, no mucosal relief. These papillae are located just in front of the V of vallate papillae, they are clustered into two groups on each side of the tongue. These contain taste buds and they get their name because of the shape which is an elongated fold that looks like a leaf seen from edge-on. Along with Circumvallate papillae and Fungiform papillae, these contain taste buds in their walls, these papillae are innervated by facial nerve supplying to the anterior papillae and the glossopharyngeal nerve to the posterior papillae. Watery secretions of Serous Glands of Von Ebner washes out these trenches so new taste can be perceived. The foliate papillae contain 1000 taste buds. Vallate (Circumvallate Papillae) The largest papillae of the Tongue 1 mm in height and 2-3 mm in diameter About 8-10 papillae at the anterior edge of the sulcus terminalis Carries 100 Taste buds for bitter taste. Ebner’s glands – serous glands, no striations, surrounded by myoepithelial cells. Saliva from these glands floods the trench around the papilla and serves as a solvent for food substances. Are dome shaped structures located anterior to the foramen cecum and sulcus terminalis. The papillae form a row on either side, two rows run backwards and medially meeting in the midline. The papillae has the shape of a truncated cone with the smaller end being directed downward and attached to the tongue, the broader part or base projecting a little above the surface of the tongue has numerous secondary papillae. The papillae are 10 to 12 in number and are the least in number but the largest in size compared to the other three types of papillae found, these papillae contain around 250 taste buds. The papillae are separated from the surface of the tongue with a ‘V’ shaped sulcus located around the papillae. It is lined by keratinized stratified squamous epithelium at the superficial surface and non-keratinized epithelium on the lateral surface, taste buds are seen on this lateral surface. The central portion of the papillae has connective tissue. TASTE BUDS Cells are Epithelial in origin. Barrel-shaped or hazel nuts-shaped structures with ovoid epithelial cells. Composed 0f 30-100 spindle-shaped cells at their bases. Located in the papillae of the Tongue, Soft Palate, Epiglottis, Larynx and Pharynx. With club-shaped sensory nerve-endings arising from the gustatory nerve fibers (glossopharyngeal, vagus and chorda tympani nerve). Taste Pore – a small opening, communicates with the epithelial surface. 4 Cells of Taste Buds Type I Taste Cells/Dark Cells 10-14 in each taste bud For the synthesis and secretion of pore substances which fills the spaces between the tips of the cell processes extending beyond the base of the pore. Dark Cells because their nuclei are rich in heterochromatin. The free ribosomes, rough endoplasmic reticulum and cytoplasmic filaments are closely packed giving the cytoplasm a dark appearance. Type II – Supporting/Sustentacular/Light Cells Low in heterochromatin Forms short apical cytoplasmic processes, with many short microvilli, where they reach the floor of the pore. No known function Type III Intermediate Cells The actual receptor cells of the taste buds. Least numerous in population. Cytoplasm ends apically as a short, blunt process at or above the bottom of the pore. Their nuclei are rich in heterochromatin. Type IV Basal Cells Perpendicular to the basal lamina. The stem cell for the other types of cells. LYMPHATIC SUPPLY Tongue has plenty of lymphatic supply. Drainage of the apex is received by mental nodes to the submandibular and deep cervical nodes. Lymph form the body of the tongue drains into the submandibular nodes and from the base, lymph flows to the deep cervical nodes. TONSILS Are masses of lymphoid tissues. Function: to produce lymphocytes For: immunization 4 in number and forms a protective ring of Waldeyer along the buccopharyngeal junction. 1. Two palatine or faucial tonsils 2. Lingual Tonsils 3. Pharyngeal Tonsils (adenoids) Salivary Glands Salivary glands are exocrine glands that make, modify and secrete saliva into the oral cavity. 2 groups of Salivary Gland: 1. Major Salivary Glands (Extrinsic Glands) a) Parotid Gland b) Submandibular Gland c) Sublingual Gland 2. Minor Salivary Gland (Intrinsic Gland) a. Labial Gland b. Small buccal gland c. Palatine Gland d. Anterior and Posterior lingual gland e. Von Ebner’s Gland f. Glossopalatine gland The Teeth Functions: 1. Masticatory 2. Facial Structure 3. Speech Dentition are classified by the number of teeth: 1. Monophyodont – 0ne set of teeth 2. Diphyodont – two sets of teeth 3. Polyphydont – several sets of teeth Heterodont Dentition Heterodont Dentition - teeth grouped according to size, shape, form and function Incisors – to incise or cut foods Canines – for tearing Premolars – for crushing Molars – for grinding Diphyodont The Human Teeth Temporary Teeth or Primary Teeth – consist of 20 teeth on both jaws and last to about 12 years of age. Permanent Teeth – 32 teeth, supposed to last till the end of life. Dental Tissues Consists of: Tooth Tissue Proper - Hard Tissue a. Enamel – the hardest calcified tissue covers the crown. b. Dentin – the main bulk of the tooth underneath the enamel and cementum. c. Cementum – calcified tissue that covers the root. - Soft Tissue Pulp – soft connective tissue found at the center of the tooth. Supporting or Investing Tissue - Gingiva – firm oral mucosa around neck of teeth. - Periodontal Ligament – fibrous connective tissue found in between the roots of tooth and alveolar bone. - Alveolar Bone – part of maxilla or mandible that forms the alveolar socket where roots of teeth are embedded. - Cementum A tooth can be divided into two main parts – the crown and the root. The part of a tooth which is visible in the mouth is referred to as the clinical or functional crown, while the part which is not visible is, by definition, the clinical or functional root. Anatomically, the crown and root can be distinguished based on their structure and the type of hard tooth tissue covering the external surface. Generally, the anatomical crown is covered by enamel, while the anatomical root is covered by cementum.  ParaOral Tissues Are structures functionally associated with the oral cavity. An organ system which contribute to the functions of: 1. Mastication – the process of biting, cutting, crushing and grinding of foods by the teeth with the aid of the lips, cheeks, tongue and palate. 2. Ingestion – the engulfing or taking of foods with the help of the lips and teeth. 3. Deglutition – the act of swallowing food. 4. Taste - Taste is the sensation that occurs in the mouth when a substance reacts chemically with taste receptor cells located on taste buds or papillae. 5. Digestion – The physical digestion of foods involve mastication and lubrication. The chemical digestion involves the preliminary digestion of carbohydrates thru the action of ptyalin. The cheeks, tongue, palate and salivary glands are involved in digestion. 6. Speech - the ability to express thoughts and emotions through vocal sounds and gestures. Structures of the oral cavity involved in forming consonants: 2 groups: A. Static (immovable) B. Dynamic (movable) 1. Teeth 1. Lips 2. Hard Palate 2. Cheeks 3. Tongue 4. Soft Palate (uvula)  4 Types of consonants: 1. Labial Consonants – involves the lip or lips bilabial “b”, “m”, “p” labio-dental “f”, “v” – lower lip and teeth labio-guttural “wh” where, what – lips and base of the tongue 2. Dental Consonants – involves the teeth and tip of the tongue “th” that tip of the tongue touches the incisal surfaces of anterior teeth “d”, apex of the tongue touches the lingual surfaces of the upper teeth “t” dorsum of the tongue is elevated “z” apex of the tongue is elevated “sh” 3. Palatal Consonants - the apex and dorsum of the tongue touches the palate “r”, “y” roll and yellow 4. Guttural Consonants – the base of the tongue elevates, touching the soft palate in forming the sound like for letter “g” in gold. 7. Respiration – oral cavity is a necessary adjunct to the respiratory system because although air travels thru the nose, in cases of nasal obstruction or congestion, air maybe inhaled or exhaled thru the mouth. 8. Protection – the protective feature is preformed by the tonsillar ring (ring of Waldeyer) and includes the phagocytic activity of macrophages against harmful bacterial and foreign bodies, immunization believed to be produced by antibodies from lymphocytes and plasma cells.