Az Atm Biomechanikaja

Biomechanics of the TMJNeuroanatomy and Physiology

Internal structures of the TMJ1. Articular disc - -biconcave, thicker on outside edges- no vascular or nervous supply except at edges- made of fibrous tissue2. 2 Joint cavities - TMJ is a compound jointa. inferior - below the discb. superior - above the disc3. Retrodiscal tissue- superior retrodiscal lamina - attaches to glenoid fossaand pulls disc back when mandible opens

Inferior joint cavitySuperior retrodiscal laminaSuperior joint cavitySuperior Lateral PterygoidInferior Lateral PterygoidRetrodiscal tissuesInferior retrodiscal laminaAnterior capsular ligamentAnterior capsular ligamentArticular surface

Retrodiscal tissuesSynovial fluid in disc spaces

Anterior view of TMJ

Superior joint cavity

Inferior joint cavity?

TMJ ClassificationFunctions as a unique joint.Anatomically is a compound joint

Biomechanics of the TMJTwo distinct joint systems1. Rotational movement- inferior joint cavity2. Translational movement- superior joint cavity

Rotation occurs around the horizontal condylar axis

Posterior border of the mandible moves back during rotationRotational movement stops when the oblique band of the Temporomandibular ligament becomes tight

Translational movement begins after TM ligament becomes tight. Condylar head starts to move down the eminentia

A to B = 20-25 mmA to C = 40-45 mm

During opening, SLP is not contractingILP is contracting - pulls head of condyle forwardAt maximum opening, SRDL is tightOpening

ClosingSuperior Lateral Pterygoid contracts and opposes force of Superior Retrodiscal Lamina

ClosingSLP contractsILP relaxesSRDL relaxes

Orthopedic Principles of TMJ Biomechanics1. Ligaments do not actively participate in TMJfunction. They limit movement.2. Ligaments do not stretch3. The articular surfaces of the TMJ must maintain constant contact

Innervation of the TMJ1. Auriculotemporal2. Masseteric3. Posterior deep temporal

Arterial supply to the TMJ1. Branches of the superficial temporal artery- Transverse facial- Middle temporal- Zygomatico-orbital2. Branches of the deep maxillary artery- Deep auricular- Anterior Tympanic- Middle Meningeal- Posterior branch of Deep Temporal- Masseteric

Pouring rubber molds

1. Rinse debris out

Spray with surfactant (debubblizer)

Surfactant reduces surface tension

Add stone in small increments from one area while placing rubber mold on vibrator

Bubbles from trapped air while pouring stone

Trim base of model flat and parallel with occlusal surface of the teeth

Omnivac machines

heater vacuumsheet of plastic