BDS TMJ & Muscles of Mastication, GIT PDF

Dr. Rana Aly Elbeshbeishy (MD, MSC & PhD Faculty of Medicine, Ain Shams University, Egypt MHPE Ottawa University, Canada) Professor RAKMHSU [email protected]; Office- 209,First Floor, Ext. 262  Muscles of mastication (4)...

Dr. Rana Aly Elbeshbeishy (MD, MSC & PhD Faculty of Medicine, Ain Shams University, Egypt MHPE Ottawa University, Canada) Professor RAKMHSU [email protected]; Office- 209,First Floor, Ext. 262  Muscles of mastication (4) 3) Lateral 1)Temporalis Pterygoid Parotid duct piercing Orbicularis buccinator Oris 2) Masseter These muscles 4) Medial -Function at TMJ (originate on skull, insert on mandible) Pterygoid -Supplied by CN V3 (Motor division) -Close the jaw: Temporalis, masseter, medial pterygoid Note: Orbicularis oris and -Open the jaw: Lateral pterygoid (bilateral) buccinator are muscles of -Retract the jaw: Temporalis -Protract the jaw: Lateral pterygoid (bilateral) facial expression but 2o -Move jaw side to side: both pterygoids (unilateral contraction) facilitate mastication  Temporalis Muscle Fan shaped (triangular) muscle Origin: Floor of temporal fossa and deep surface of temporal fascia. Insertion: Into the coronoid process and anterior border of ramus of mandible. Nerve supply: Deep temporal nerves (from the anterior division of mandibular nerve). Action: Elevation of mandible by anterior vertical fibers (close jaws) Retraction (the only retractor of Mandible) by the posterior horizontal fibers  Masseter Muscle Quadrate muscle consists of 3 layers which blend anteriorly. Origin: zygomatic arch, its lower border & medial surface Insertion: angle and lateral surface of ramus of mandible. Nerve supply: Masseteric nerves (branch of anterior division Mandibular division (V3) of trigeminal nerve (V). Action: Elevates mandible to occlude teeth in mastication. It has a small effect in side-to-side movements, protraction and retraction. Lateral pterygoid muscle Origin: Has 2 heads: – superior head → infratemporal surface of greater wing of sphenoid – inferior head → lateral surface of lateral pterygoid plate Insertion: Intra-articular disc – pterygoid fovea on neck of mandible. – capsule and intra-articular disk of TMJ. Superior head Action: protrudes and depresses mandible (open mouth) Side to side movement (chewing) Peripheral pump for pterygoid plexus of veins Inferior head Nerve supply: Nerve to Lateral pterygoid (Branch of anterior division of Mandibular nerve (V3)  Medial pterygoid muscle Origin: Has 2 heads: - Superficial head → from Tuberosity of maxilla - Deep head → from Medial surface of lateral pterygoid plate Insertion: – to deep surface of angle of mandible Tuberosity of maxilla Action: - Elevation, protrusion, side to side movements Nerve supply: Nerve to medial pterygoid (Branch of Mandibular nerve trunk (V3) Muscle fibers run downwards, backwards, & laterally Important relations around lateral pterygoid muscle Outside (superficial) – maxillary A Inside (deep) – Mandibular N., Otic ganglion, Middle meningeal A. Around – pterygoid venous plexus – communicates with facial vein & intracranial veins – can spread infection from face to brain  Temporomandibular joint (TMJ) Type: modified hinge synovial joint or condylar synovial Articulating bones: Mandibular fossa & articular tubercle of Temporal bone superiorly Head of mandible inferiorly. articular surfaces are covered by fibro-cartilage (no hyaline cartilage) Mandibular head Mandibular fossa & articular tubercle  Articular disc The upper surface is concavo-convex to fit into the articular tubercle and mandibular fossa of temporal bone. The lower surface is concave to fit into the head of mandible. It divides the joint cavity into upper and lower compartments. It receives part of insertion of lateral pterygoid. Partial detachment of the disc from the capsule producing an audible click during movement at the joint. Temporomandibular Joint (TMJ) Anatomy and Disc Displacement Animation - YouTube  Capsule of TMJ Capsule The joint capsule encloses the temporomandibular joint and is attached: Above along anterior margin of articular tubercle and margins of mandibular fossa. Below around upper part of neck of mandible 10  Two extrinsic ligaments 1. Stylo-mandibular ligament Attached from styloid process to angle of mandible 2. Sphenomandibular ligament Medial to joint – from spine of the sphenoid to lingula of mandible sphenomandibular Lig. Pierced by mylohyoid vessels and nerves Stylomandibular Lig. Lateral aspect of TMJ Sphenomandibular ligament Stylo-mandibular ligament Medial aspect of TMJ  1 Intrinsic ligament Lateral temporomandibular ligament Strengthens lateral aspect of capsule prevents lateral displacement of head Prevent posterior dislocation of condyle, together with the postglenoid tubercle, → protects the external auditory meatus.  Movements of the TMJ The gliding movements of protrusion and retrusion occur between the temporal bone and the articular disc (superior cavity) The hinge movements of depression and elevation and the rotational occur in the inferior compartment. Side to side:- alternate contraction Medial and Lateral pterygoid lateral Pterygoids.  Movements of the TMJ Protrusion:- Lat. Pterygoid helped by med. pterygoid. Retraction:- by post. Fibers of Temporalis. Depression:- Lat. pterygoid, helped by digastric, mylohyoid & geniohyoid. Elevation:- Temporalis , masseter & med. pterygoid. Side to side:- alternate contraction Medial and lateral Pterygoids. 14  Nerves and Vessels related to TMJ Auriculotemporal nerve Masseteric nerve Auriculotemporal nerve Superficial temporal artery Masseteric branch of mandibular nerve Maxillary A. Maxillary artery 15  Dislocation of TMJ typically Anterior common in old people due to laxity of ligaments & capsule. occur during excessive opening of the mouth → the head of mandible slips anteriorly and there is inability to close the mouth. In bilateral cases the mouth is fixed in an open position, and both heads of the mandible lie in front of the articular tubercles. Clinical Notes TMJ dislocation Reduction http://www.youtube.com/watch?v=aGknbegDkl4  General Outline of Gastrointestinal Tract (GIT) Digestive System consists of: 1- Alimentary canal (tract), also called gastrointestinal tract (GIT) → begin from oral cavity and end at anus. Organs: mouth, pharynx, esophagus, stomach, small intestine & large intestine. alimentary canal is approximately 9 m long. 2- Accessory digestive organs are teeth, tongue, gallbladder, and a number of large digestive glands: salivary glands, liver, and pancreas.  Esophagus Muscular tube About 25 cm long carry food to stomach connects pharynx with stomach it consists of three parts 1-Cervical part 2-Thoracic part 3-Abdominal part (smallest part)  Stomach Dilated part of the GIT lies in the abdominal cavity Store and digest food Secrete HCL acid Stomach is divided into 4 regions: 1- Cardia (cardiac sphincter): surrounds the opening of esophagus into stomach 2- fundus of stomach: area above level of cardiac orifice 3- body of stomach: the largest region of stomach 4- Pyloric part (Pylorus): divided into pyloric antrum , pyloric canal & pyloric sphincter  Small intestine Duodenojejunal Junction Extends from pyloric orifice of stomach to ileocecal junction Duodenum is approximately 6 m Jejunum long consists of: duodenum, jejunum and ileum Cecum duodenum site of digestion Ileum jejunum and Ileum site of absorption Ileocecal Junction  Large intestine extends from ileocecal valve to anus. It consists of: 1. Cecum 2. Appendix 3. Ascending colon 4. Transverse colon 5. Descending colon 6. Sigmoid colon 7. Rectum 8. Anal canal Function: Reabsorption of water , electrolytes and excretion of feces