Norma Lateralis and TMJ PDF

NORMA LATERALIS The Lateral View of the Skull The Bones Involved in Norma Lateralis 1. Temporal Bone 2. Parietal Bone 3. Occipital Bone 4. Frontal Bone 5. Zygomatic Bone 6. Maxilla 7. Mandible 8. Nasal Bone 9. Sphenoid Bone 10. Lacrimal Bone.  The Two Divisions of...

NORMA LATERALIS The Lateral View of the Skull The Bones Involved in Norma Lateralis 1. Temporal Bone 2. Parietal Bone 3. Occipital Bone 4. Frontal Bone 5. Zygomatic Bone 6. Maxilla 7. Mandible 8. Nasal Bone 9. Sphenoid Bone 10. Lacrimal Bone.  The Two Divisions of the Skull in Norma Lateralis 1. Cerebral Portion - located above the zygomatic arch. 2. Facial Portion - located below the zygomatic arch. The Characteristic Features of the Cerebral Portion 1. Temporal Lines 2. Supramastoid Crest 3. Temporal Fossa 4. Zygomatico-temporal foramen 5. Zygomatic arch 6. Infratemporal line/crest 7. Infratemporal fossa 8. Suprameatal triangle 9. Pterion 10. Asterion. 15 28 27 The Characteristic Features of the Facial Portion 1. Zygomatic arch 2. Articular tubercle 3. External acoustic meatus 4. Mandibular fossa 5. Styloid process 6. Mastoid temporal 7. Mastoid process 8. Mastoid foramen 9. Gonion. 10. Pterygo-maxillary fissure 11.Pterygo-palatine fossa 12.Spheno-palatine foramen. The Temporal Bone  Four Parts of the Temporal Bone  1. Squamous part  2. Mastoid part  3. Tympanic part  4. Petrous part (Lateral Dissection) The Three Fossae in Norma Lateralis 1. Temporal Fossa 2. Infratemporal Fossa 3. Pterygopalatine Fossa The Temporal Fossa  A flat, fan-shaped depression on the lateral surface of the skull. Bones involved: 1. Zygomatic Bone 2. Frontal Bone 3. Greater Wings of Sphenoid 4. Temporal Bone 5. Parietal Bone  Boundaries of the Temporal Fossa Boundaries Structure Superior Inferior Temporal Line Anterior Frontal Process of Zygomatc Bone Medial Surface of Temporal Bone and GWS Lateral Zygomatic Arch Inferior Infratemporal Crest of Sphenoid Bone Posterior Inferior Temporal line  Contents of the Temporal Fossa 1. Temporalis muscle is attached to its floor. 2. Pterion – a small circular area where the frontal, parietal, sphenoid, and temporal bones are close together. The Infratemporal Fossa - A paired depression that is inferior to anterior part of the temporal fossa. - Divided from the temporal fossa by the crest of the greater wings of sphenoid.  Boundaries of the Infratemporal Fossa Boundaries Structure Superior Greater wings of sphenoid Anterior Maxillary tuberosity Medial Lateral pterygoid plate Lateral Mandibular ramus and zygomatic arch Inferior No border Posterior No border  Contents of the Infratemporal Fossa 1. The mandibular division of the trigeminal nerve, 2. Contains pterygoid plexus and the pterygoid muscles, 3. Maxillary artery and its branches, middle meningeal artery, 4. Inferior alveolar artery, 5. Posterior alveolar artery. The Pterygopalatine Fossa - A cone-shaped depression, deep into the infratemporal fossa. - Its is located between the pterygoid process and the maxillary tuberosity near the apex of the orbit.  Boundaries of the Pterygopalatine Fossa Boundaries Structure Superior Inferior surface of the body of the sphenoid Anterior Maxillary tuberosity Medial Perpendicular plate of the palatine bone Lateral Pterygomaxillary fissure Inferior Pterygopalatine canal Posterior Pterygoid process of the sphenoid bone  Contents of the Pterygopalatine Fossa 1. Maxillary artery and its branches, 2. Pterygopalatine ganglion, 3. Maxillary nerve. THE TEMPOROMANDIBULAR JOINT - is a complex articulation of the movable mandible and the base of the skull. Articulation takes place in two areas: 1. Between maxillary and mandibular teeth ( interjaw dental occlusion ), and 2. Between the mandibular condyle and the temporal bone.  Bones Involved in the TMJ 1. Condylar process or condyle of the mandible 2. Mandibular fossa 3. Articular emminence of the temporal bone Components of the TMJ 1. Articular or Fibrous Capsule 2. Temporo-mandibular (lateral) Ligament 3. Articular Disc 4. Joint Cavities 1. Articular or Fibrous Capsule - encloses the joint surfaces like a sleeve that runs from the temporal bone superiorly, to the condyle of the mandible inferiorly. The enclosed space between the articular surfaces is the joint cavity Superior attachment : area surrounding the mandibular fossa and articular eminence of the temporal bone. Inferior attachment: periphery of the mandibular condyle. 2. Temporomandibular (lateral) Ligament  - is a lateral thickening of the joint capsule and is similar to the collateral ligaments of other joints. - It prevents posterior and inferior displacement of the condyle but allows limited anterior movements of the condyle. 3. Articular Disc - it is composed of dense fibrous tissues and lies within the joint capsule, intervening between the condyle and the mandibular fossa. - It is a biconcave disc that serves to provide reciprocal articular surfaces between its inferior surface and the condyle, and its superior surface and the mandibular fossa and eminence.  Three zones of the articular disc: 1. Posterior thickening – sits atop the condyle and fills the mandibular fossa above when the mandible is at rest. 2. Anterior thickening - lies just below the posterior slope of the articular eminence. 3. Intermediate zone - lies between the two previous zones. 4. Joint Cavities  The disc effectively divides the joint cavity into two distinct upper and lower compartment that allow two types of joint movements. These cavities are also filled with synovial fluid which nourishes the articular disc. Accessory Ligaments  Two accessory ligaments span the joint but do not significantly limit mandibular movements: 1. Sphenomandibular ligament - it runs from the spine of the sphenoid bone to the lingula of the mandible. 2. Stylomandibular ligament - it runs from the styloid process of the temporal bone to the angle of the mandible. The Synovial Membrane  A layer of synovium lines the inner aspects of the joint capsule. This relatively dense membrane does not line the actual articular surfaces of the joints because synovial joints are generally weight-bearing joints. The pressure in the TMJ is provided by the occluded maxillary and mandibular teeth. Synovium secretes synovial fluids for lubrication and nourishment of the opposing articular surfaces.  Two Layers of the Synovial Membrane 1. An intimal cellular layer - contains type A cells which are phagocytic, and type B cells which synthesize hyaluronate found in synovial fluid. 2. A vascular subintimal layer - Contains blood vessels, and lymphatics within the loose connective tissue matrix. Nerve Supply of the TMJ 1. Branches of the temporalis N. 2. Branches of the auriculotemporal N. 3. Branches of the masseteric N. Blood Supply of the TMJ 1. Superficial temporal artery 2. Muscular branches of the maxillary artery Temporomandibular Joint in Action Muscles Acting on the TMJ 1. Masseter 2. Temporalis 3. Lateral Pterygoid 4. Medial Pterygoid The Medial Pterygoid The Lateral Pterygoid The Temporalis The Masseter Muscle Protrusion: 1. Lateral pterygoid m. 2. Medial pterygoid m.  Retraction 1. Temporalis M. Synergists: a. Masseters b. Digastric c. Geniohyoid Elevation 1. Temporalis 2. Masseter 3. Medial pterygoid  Depression 1. Lateral pterygoid Synergists: 1. Digastric 2. Geniohyoid 3. Mylohyoid  Lateral movements 1. Medial pterygoid m. 2. Lateral pterygoid m.