The Articular System Joints Chapter 8 The Articular System Joints

Introduction Articulation: union between two or more bones Can be mobile or immobile Examples skull bones Knee or elbow joint

The Classification of Joints: Structure and Function

Introduction Joints are classified into three major groups based on: Degree of movement allowed (function) Type of material holding bones together (structure) 1-synarthroses( joints that do not allow movements) 2- Amphiarthroses(joints that allow only slight movement. 3- Diarthroses or synovial joints( Freely moving joints or articulations)

Movements at Synovial Joints

Movements at Synovial Joints (cont’d.) Flexion/extension Hyperextension: abnormal extension Dorsiflexion/plantar flexion Abduction/adduction Rotation Circumduction

Movements at Synovial Joints (cont’d.) Supination/pronation Eversion/inversion Protraction/retraction Opposition/reposition

Flexion and extension Flexion : The act of bending or decreasing the angle between bones. Extension: The act of increasing the angle between bones and is the opposite of flexion.

Hyperextension Hyperextension : It increases the joint angle beyond the anatomic position.

Abduction and adduction Abduction: Is moving the bones away from the midline of the body. Adduction: Is moving the bone toward the midline of the body.

Rotation and circumduction Rotation: Is the act of moving the bone around a central axis. Circumduction: Is moving the bone in such a way that the end of the bone describe the circle in the air and the sides of the bone describe a cone in the air.

Supination and pronation Supination: Is moving the bones of the forearm so that the radius and ulna are in parallel. Pronation :Is moving the bones of the forearm so that the radius and ulna are not parallel.

Eversion and inversion Eversion : Is the moving the sole of the foot outward at the ankle. Inversion: Is moving the sole of the foot inward at the ankle.

Other movements Protraction : Is moving a part of the body forward on a plane parallel to the ground. Retraction : Is moving a part of the body backward on a plane parallel to the ground. Elevation :Is raising a part of the body. Depression : Is lowering a part of the body.

Opposition Opposition : Is movement that occurs only with the thumb. It occurs when the tip of the thumb and the fingers are brought together.

Reposition Reposition : When the digits return their normal positions.

Dorsiflexion and plantar flexion Dorsiflexion : Is raising the foot up at the ankle joint. Plantar flexion: Is pushing the foot down at the ankle joints, actions we do when walking.

Diagrams

The Six Types of Diarthroses or Synovial Joints

The Six Types of Diarthroses or Synovial Joints (cont’d.) Ball-and-socket Widest range of movement Movement can occur in all planes and directions Shoulder Hip

The Six Types of Diarthroses or Synovial Joints (cont’d.) Ball-and-socket

The Six Types of Diarthroses or Synovial Joints (cont’d.) Hinge Convex surface fits into concave surface Flexion and extension only Knee Elbow  Hinge joints are formed between two or more bones where the bones can only move along one axis to flex or extend.

The Six Types of Diarthroses or Synovial Joints (cont’d.) Hinge

The Six Types of Diarthroses or Synovial Joints (cont’d.) Pivot Rotation in one plane Atlas and axis (cervical spine) Rotation of the head

The Six Types of Diarthroses or Synovial Joints (cont’d.) Pivot

The Six Types of Diarthroses or Synovial Joints (cont’d.) Condyloid (ellipsoidal) Oval-shaped condyle fits into elliptical cavity Motion in two planes at right angles Radius and carpal bones This permits movement in two planes, allowing flexion, extension, adduction, abduction, and circumduction.

The Six Types of Diarthroses or Synovial Joints (cont’d.) Condyloid (ellipsoidal)

The Six Types of Diarthroses or Synovial Joints (cont’d.) Saddle Motion in two planes at right angles Permits opposition of the thumb Saddle joints provide stability to the bones while providing more flexibility than a hinge or gliding joint.

The Six Types of Diarthroses or Synovial Joints (cont’d.) Saddle

The Six Types of Diarthroses or Synovial Joints (cont’d.) A gliding joint, also known as a plane joint or planar joint, formed between bones that meet at flat or nearly flat articular surfaces. Gliding joints allow the bones to glide past one another in any direction along the plane of thejoint – up and down, left and right, and diagonally. Gliding motion Intervertebral joints in spine

The Six Types of Diarthroses or Synovial Joints (cont’d.) Gliding