Oral Cavity Anatomy PDF

ORAL CAVITY The Oral Cavity: THREE BASIC STRUCTURES 1. Oral mucosa – the mucous membrane that covers the entire oral cavity except...

ORAL CAVITY The Oral Cavity: THREE BASIC STRUCTURES 1. Oral mucosa – the mucous membrane that covers the entire oral cavity except the teeth. It may range from the color pink to brownish purple. The body skin The oral cavity or the mouth is an important color, the location of the oral cavity and part of the human body. From the basic its function all contribute to form the function to initial diagnosis of systemic color of the oral mucosa diseases, it is an important indicator of our 2. Muscles – lips, cheeks, and the tongue, general health. all contain muscles in some form or the other. They facilitate the movements in STRUCTURES THAT OVERALL COMPRISE OF the oral cavity to accomplish various THE ORAL CAVITY: oral functions. 1. Lips 3. Bones – the upper jaw (maxilla) and the 2. Teeth lower jaw (mandible) are the bony 3. Gums and supporting structures known components of oral cavity as PERIODONTIUM 4. Muscular tongue (flexible) – attached to the floor of the cavity 5. Palate – the ceiling of the cavity 6. Muscular folds – facial muscles connecting the oral cavity to the throat 7. Salivary glands enclosed in the floor and the buccal aspect of the oral cavity 8. Floor of the mouth 9. Tongue 10. Jaw point or the temporomandibular joint (TMJ) – important for the movement of the jaw to perform major functions  CHEEKS LAYERS OF THE CHEEKS 1. Skin 2. Dermal muscles 3. Corpus adiposum buccae 4. Buccinator muscles THE EXTERNAL MOUTH Composed primarily of the upper and lower lip Separated from the skin by the vermilion border (outer red border) CHEEKS VERMILION BORDER: STRATIFIED Buccal mucosa SQUAMOUS KERATINIZED EPOTHELIUM o STRATIFIED SQUAMOUS NON- INTERNAL SURFACE OF THE LIP: KERATINIZED EPITHELIUM STRATIFIED SQUAMOUS NON- PAROTID PAPILLA KERATINIZED EPITHELIUM - Is a small elevation of tissue that marks BOUNDED: the opening of the parotid duct on the o Superiorly by the Philtrum inner surface of the cheek o Supero-laterally by the Naso- labial fold o Inferiorly by the Mento-labial fold LIPS o Medially by the buccal and labial Outlining the cavity externally are the surface of the upper and lower only visible external part of the oral teeth cavity, serving as an upper seal to the o Posteriorly by the retromolar area digestive tract Covered with skin on the outside and mucosa on the inner side, together they are gateway to the oral cavity Their functions involve food and water intake as well as articulation of speech PARTS OF THE EXTERNAL MOUTH Muscles that support the external mouth is the “ORBICULARIS ORIS MUSCLE” 2. Oral cavity proper FUNCTIONS OF THE MOUTH o Laterally by palatal and lingual 1. The first part of the digestive system surfaces of the upper and lower wherein mastication occurs jaw 2. T receives food (ingestion) and breaks o Superiorly by the palate (hard up the food into smaller pieces and soft) (digestion) o Inferiorly by the tongue and floor 3. Takes part in respiration as well as in of the mouth speech production o Posteriorly by the isthmus of 4. It conveys emotions fauces THE 2 DIVISIONS OF THE ORAL CAVITY HARD PALATE - Is anterior part of the palate - Consisting of the bony plate covered above by the mucous membrane of the nose - Covered by KERATINIZED GRAYISH RED TO CORAL PINK TISSUE - There is a small, rounded elevation of tissue on the midline lingual to the central incisors called the incisive papilla - Under this papilla is the incisive foramen where the NASOPALATINE NERVE exits from the nasal cavity to 1. Oral vestibule is a slit like space innervate the anterior portion of the bounded: hard palate o Laterally by cheeks and lips  a projection of tissue known as the uvula hangs down from the middle of the soft palate over the root of the tongue it is thought that the uvula functions to keep food from straying down the breathing passage or the windpipe during swallowing - The palatine raphe is an elevated tissue line in the center running from front to back of the hard palate - The tissue on both sides of the raphe is softer than the midline because of the presence of fat or salivary gland tissue - There are more than 350 tiny palatine glands located in the posterior 1/3 of the hard palate, and they are responsible for the secretion of thick and slippery saliva. - The palatine rugae are wrinkle-like tissue elevations located just behind the maxillary anterior teeth extending laterally like branches of a tree from the midline palatine raphe. They have 2 important functions: - Tactile sensing of objects or food position and - Aide in the tongue’s proper placement to produce certain speech sounds The hard and soft palate separate the mouth from nasal passage The presence of the palate makes it possible to breathe and chew at the same time The palate also aids the functions of speaking and singing. Soft palate is made up of muscular tissue that is covered by epithelial tissue. Usually redder than the hard palate because it is more vascularized  FAUCIAL PILLARS PHARYNGEAL TONSILS o Roof of nasopharynx o Ciliated pseudostratified epithelium o Drains into retropharyngeal nodes THE FAUCES are the posterior boundary of the oral cavity: the opening from the mouth to the oropharynx (throat); passage for air when breathing through the mouth and for food when eating PALATINE TONSILS since the oropharynx leads to the o The “tonsils” esophagus and then eventually to the o Tonsillar bed stomach o Non-keratinized squamous It is located between the oral cavity and epithelium the throat. There are two pillars, one in o Drains into cervical lymph nodes front (glossopalatine arch) of the tonsils and the other (pharyngopalatine arch) behind the tonsils. TONSILS LINGUAL TONSILS o Submucosa of posterior 1/3 of the tongue o Stratified squamous non- Are secondary lymphatic organ keratinized epithelium responsible for filtering inspired or o Drains into cervical lymph nodes ingested antigen from air or food These tonsils may become enlarged and inflamed in the presence of respiratory infection If infected at a later stage, doctors recommend their surgical removal  INFERIOR BOUNDARY TONGUE is highly mobile, flexible, The floor of the mouth muscular structure attached to the floor The TONGUE is composed of anterior of the oral cavity and free at the other. 2/3 The tongue is made of mainly skeletal muscle. Its upper surface is divided into two parts: ORAL PART – that lies in the oral cavity Pharyngeal part – which faces backward to the oropharynx The two parts are separated by a V-shaped groove TONGUE MUSCLES INTRINSIC MUSCLES OF THE TONGUE Superior - Shortens tongue longitudinal - Curls apex and sides of the tongue Presence of LINGUAL PAPILLAE that contains taste buds namely: Inferior - Shorten tongue longitudinal - Uncurls apex and 1. Filiform papilla – fine hair like, turns it downward numerous on the anterior 2/3 of the dorsum of the tongue Transverse - Narrows and 2. Fungiform – round, mushroom-like and elongates the tongue deep red color, concentrated near the tip of the tongue Vertical - Flattens and 3. Foliate papilla – large leaf-like widens the tongue projections on the lateral surface of the tongue 4. Circumvallate papilla – large, flat mushroom-shaped papillae forming a V- shaped row on the dorsum near the posterior 1/3 of the tongue EXTRINSIC MUSCLES OF THE TONGUE Palatoglossus - Elevates posterior part of the tongue - Depression of the soft palate  - Closes TONGUE: VASCULAR SUPPLY oropharyngeal VASCULATURE isthmus Styloglossus - Retraction of the Arterial blood supply tongue - Elevates the Lingual artery – supplies all muscles back of the EXCEPT for the Palatoglossus tongue o Palatoglossus is supplied by Hyoglossus - Depresses the branches of Maxillary and Facial lateral parts of arteries the tongue o All branches of the external - Retracts the carotid tongue - Elevates the hyoid bone Venous drainage Genioglossus - Depresses the Deep lingual veins central part of o Travels with CNXII the tongue o Exits oral cavity between - Protrudes the Mylohyoid, superior and middle anterior parts of the tongue constrictor of pharynx Dorsal lingual veins All extrinsic muscle except PALATOGLOSSUS o Follow lingual artery between is innervated by HYPOGLOSSAL NERVE Hyoglossus and Genioglossus TONGUE: NERVE INNERVATION The upper surface (dorsum) of the tongue is Hypoglossal nerve All except covered with tiny projections called papillae. PALATOGLOSSUS Our taste buds are located here. Glossopharyngeal nerve Taste and sensory of posterior 1/3 The FIVE main types Lingual nerve Sensory of anterior 2/3 Facial nerve Taste sensation of anterior 2/3 1. Sweet 2. Salty 3. Sour 4. Bitter 5. Umami The lower surface of the tongue is covered with a smooth mucous membrane, with a fold called lingual frenulum in the center. There are no lingual papillae on the underside of the tongue.  The tongue plays an important role in: INNERVATION: CN VII o Speech o Mastication (grinding food and formation of bolus) o Deglutition (swallowing) 3. Sublingual gland – produces 5-8% of our saliva, predominantly mucous (purely mucous, ropy type) LOCATED: At the floor of the mouth anteriorly, beneath the submucosa of the anterior part of the floor of the mouth, above the mylohyoid muscle - BARTHOLIN’S DUCT -> DUCTS OF The Salivary Glands: MAJOR SALIVARY GLANDS RIVINUS BLOOD SUPPLY: Sublingual and submental arteries 1. Parotid glands – the largest of 3 salivary INNERVATION: CN VII glands LOCATED: From zygomatic process to the angle of the mandible PRODUCES: watery saliva - STENSENS’S DUCT -> PAROTID PAPILLA BLOOD SUPPLY: External carotid artery INNVERVATION: CN IX MINOR SALIVARY GLANDS 2. Submandibular Gland – produces about 2/3 of our saliva (mostly serous) LOCATED: At the floor of the mouth posteriorly, submandibular triangle, below mylohyoid muscle near the inner surface of the angle of SALIVARY GLANDS the mandible MAJOR SALIVARY GLAND - WHARTON’S DUCT -> CARANCULA 1. Large glands extra orally located and SUBLINGUALS bilateral BLOOD SUPPLY: Facial and Lingual arteries 2. Contains three general structures of 4. PREVENT CARIES: through its pH salivary gland: Secretory cell, duct buffering effects and remineralization of system, connective tissue capsule teeth MINOR SALIVARY GLAND TEETH 1. Small group secretory cell HUMANS ARE DIPHYODONT meaning 2. Just beneath oral epithelium at that they develop two sets of teeth in a submucosa level lifetime 3. No duct system but have short ducts The first set of teeth, the deciduous 4. No connective tissue capsule teeth are also called the milk teeth, 5. Have secretory cell primary teeth, or baby teeth. 6. Named according to location in the oral They are replaced by a set of permanent cavity teeth, which is also called secondary, or succedaneous teeth SALIVA SALIVA is produced in and secreted STRUCTURES OF THE TEETH from the salivary glands. The tooth is a mineralized entity These cells secrete fluid that contains It can be divided into two portions; water, electrolytes, mucus and 1. Coronal structure or the crown – is the enzymes, all of which flow out of the visible portion of the tooth ACINUS into COLLECTING DUCTS 2. Radicular or the root portion – that is Secretion of saliva is under control of covered by the gingiva or the gums the AUTONOMIC NERVOUS SYSTEM, which controls both he VOLUME and TYPE of saliva secreted 93% of the saliva is secreted by major and 7% by minor salivary glands Normal daily production of saliva is over a pint (approx. ½ liter) :300 ml between meals, 300ml while eating and only 20ml while sleeping. TOOTH: TISSUE TYPES FUNCTIONS OF SALIVA Basically, the tooth consists of four 1. LUBRICATION AND BINDING: The types: mucus in saliva is extremely effective in 1. Enamel binding masticated food into a slippery 2. Dentin bolus that (usually) slides easily through 3. Pulp the esophagus without inflicting 4. Cementum damage to the mucosa The difference in crown and root of the tooth is 2. SOLUBILIZES DRY FOOD: In order to be that: tasted, the molecules in food must be CROWN: covered by ENAMEL solubilized ROOT: covered by CEMENTUM 3. CLEANING EFFECT: of washing away The second layer is the DENTIN and the PULP food debris forming the core respectively 1. ENAMEL – is the hardest tissue in the 4. PULP – is the innermost portion of the human body, covering the crown of the tooth tooth. It is highly mineralized tissue as o the pulp is soft 96% of its content is mineral organic o it is made of connective tissue, content and water comprises the rest. nerves, and blood vessel which nourish the tooth o blood vessels and nerves enter the root through a small hole at the very bottom of the tooth called the apical foramen PERMANENT TEETH The eruption of the permanent teeth begins 2. DENTIN – is a hard yellow substance, even before the first primary sheds. The makes up most of the teeth. It is the permanent teeth appear/erupt in the oral cavity dentin that gives the teeth its slightly by the age of 6 years old. It is the mandibular 1 st yellowish tint. molar there are 32 permanent teeth o 8 incisors o 4 canines o 8 premolars o 12 molars 3. CEMENTUM – covers the root and holds the tooth in place within the jawbone; is as hard as bone but not as hard as enamel. Which enables the tooth to withstand the pressure of chewing and 6 to 9 years old – The incisors and 1st protects it from harmful bacteria and molars start to appear changes in temperature from hot and 10 to 12 years old – the 1st and 2nd cold food. premolars, as well as the canines erupt 11 to 13 years old – 2nd molars erupt The phase during which permanent teeth develop usually lasts for about 15 years old. As the jaw steadily grows into its adult form. 17 to 21 years old – the wisdom teeth (3rd molars) erupt  TYPES OF TEETH teeth continue to form until they erupt in the 1. INCISORS – are the squarish, sharp- oral cavity. edges teeth at the front and middle of The primary teeth usually start erupting the mouth. They are for cutting and form the 6th month of age. biting. There are four: Central incisors (2 By the time a child is 3 yrs old, a set of maxillary, 2 mandibular), Lateral 20 deciduous teeth has erupted in the oral incisors (2 maxillary, 2 mandibular) cavity. 10 teeth on each arch 2. CANINES – (cuspids) distal to the 8 incisors incisors. These serve for piercing and 4 canines tearing. (2 maxillary, 2 mandibular) 8 molars 3. PREMOLARS – (bicuspids) distal to the canines. There are two sets of the 1st The deciduous teeth help the permanent and 2nd premolars. These are absent in teeth erupt in their normal positions; most of the primary dentition. the permanent teeth form just beneath the 4. MOLARS – distal to the premolars. roots of the deciduous teeth. Molars have cusps and grooves. There When a deciduous teeth is preparing to fall are 12 molars in the permanent out (exfoliate), its root begins to dissolve dentition: 1st, 2nd, 3rd molar in each (resorption). The root has completely dissolved quadrant. PREMOLARS and MOLARS by the time the permanent tooth below it is function is for chewing and grinding ready to erupt. GUMS and SUPPORTING BONE Gum tissue (gingiva), a specialized portion of the oral mucosa, connects to each tooth at the neck and extends over the root and supporting bone. In a healthy mouth, the root remains entirely out of sight below the gum line. The gums cover the supporting bone, called the alveolar bone that surrounds and holds the tooth to the jaw. If a gum disease spreads further down, it affects the supporting bone and causes the loosening of the tooth DECIDUOS TEETH (PERIODONTITIS) The milk teeth/primary dentition are the first set of teeth in humans and many mammas. They start to form in the embryo phase during pregnancy. The development initiates in the 6th week. The process starts at the midline and then spreads back into the posterior region. By the time of 8 weeks, there are ten areas in the upper and lower arches that will eventually become deciduous dentition. These