MANDIBULAR MOVEMENTS

TMJ has a capsule and articulating disc Two joints are mechanically coupled Is a synovial joints,,its bony components covered with dense fibrous tissue NOT by hyaline cartilage Glenoid fossa of temporal bone & condyle of mandible = articulating surface

Articular disc divides joints into upper & lower components Upper components show anterior posterior gliding movement Lower components show hinge movement TMJ is capable of function and Para function movements Movements are similar in dentulous and edentulous patients Occlusion in complete denture should be in harmony with these movements

***`Mandible moves to carry out functions of Mastication Swallowing Speech Expression Para functional habits

WHAT MUST I STUDY?????

TMJ ARTICULATION Bony structures Fossa & condyles Ligaments Articular disc (meniscus) Muscles

*****Ligaments (to limit motion in the joint) Capsular ligament Tempromandibular ligament Sphenomandibular ligament Stylomandibular ligament

MUSCLES Temporal muscle Posterior part to retrude the mandible Middle part elevates it in centric position No biting force when mandible is in protrusion, so it can be used to determine whether the patient is closing in centric relation.

Medial pterygoid muscle The action of the muscle is an elevator Does not assist in the lateral or protrusive movements

Lateral petrygoid muscle The principle action is the protrusion of one or both condyles. It guides the mandible into lateral or protrusive positions.

Masseter (elevation) Remember : extension of buccal flange (disto buccal)

MUSCLES OF DEPRESSION Suprahyoid Geniohyoid Mylohyoid Stylohyoid Platysma Are the primary movers of the mandible

Mylohyoid muscle Its principle action is to assist in swallowing

Opposing teeth are in contact Movements are controlled by neuromuscular system as limited by the condyles and the guide influences of the contacting teeth Opposing teeth are not in contact, movements are controlled by musculature as limited by condyles and ligaments.

CLASSIFICATION OF JAW RELATIONS Orientation relation Mandible can rotate in the sagittal plane Vertical relations Amount of jaw separation Horizontal relation Front to back and side to side

MANDIBULAR MOVEMENTS Rotation concentric circles around a common axis Transolatory points of the body move in the same velocity and direction

AXES OF ROTATION Saggital Vertical Transverse

Rotational Movement Around the sagittal axis

Rotational Movement Around the horizontal axis

Rotational Movement Around the frontal (vertical) axis

Opening and closing movements Lateral excursions Protrusive movement

Bennett Movement & Angle The angle formed by the sagittal plane and the path of the advancing condyle during lateral mandibular movements as viewed in the horizontal plane.

i`m going to study What about you?????