Types of Synovial Joints

Types of Synovial Joints

Synovial joints are not all identical. There are six ­further subdivisions of synovial joints: gliding, hinge, pivot, ellipsoidal, saddle, and ball-and-socket joints.

Gliding Joints

Gliding joints have nonaxial movement that involves linear gliding and flat, articular surfaces. For exam-ple, the intercarpal joints, intertarsal joints, sacroil-iac joints, and the joints between vertebral articular surfaces.

Hinge Joints

Hinge joints have uniaxial movement that involves flexion and extension along a medial/lateral axis. They also have cylinders and troughs. For example, the elbow joints and interphalangeal joints.

Pivot Joints

Pivot joints have uniaxial movement that involves rotation around a vertical axis. They have bone and ligament sleeves as well as rounded bones (axles). For example, the proximal radioulnar joints and the atlan-toaxial joint.

Ellipsoidal Joints

Ellipsoidal joints have biaxial movement that involves adduction and abduction around an anterior/­ posterior axis as well as flexion and extension around a medial/lateral axis. Their articular surfaces are oval-shaped. For example, the metacarpophalangeal (knuckle) joints, radiocarpal joints, and wrist joints.

Saddle Joints

Saddle joints have biaxial movement that involves flexion and extension as well as adduction and abduc-tion. These joints function around the same type of axis configurations as condylar joints. Articular sur-faces are both concave and convex. For example, the carpometacarpal joints of the thumbs.

Ball-and-Socket Joints

Ball-and-socket joints have multiaxial movement that involves rotation, adduction, abduction, flexion, and extension. These joints use vertical, anterior/­ posterior, and medial/lateral types of axis structures, with spherical heads in cup-like sockets. For example, the shoulder and hip joints. Types of synovial joints are shown in FIGURE 8-3.

1. List different types of synovial joints.