|  | Conditions Treatments | Bones, Joints Muscles

What Type of Movable Joint Is the Elbow?

The musculoskeletal system of the human body is comprised of bones forming the skeleton, muscles that move these bones, and ligaments that hold these bones together. Synovial joints are formed where two bones come together with cartilage, or cushioning, between them. Muscles produce movement at these joints using tendons that connect the muscles to these bones. There are several different types of synovial joints in the human body.

  1. Hinge Joint

    • A hinge joint moves in only one plane: forward and back in a 180-degree arc. These movements are called flexion (bending) and extension (straightening). The elbow joint is an example of a hinge joint. It is formed by the humerus, or upper arm bone, articulating with the ulna, the forearm bone that runs in line with the pinkie side of the hand. The knee joint, formed by the femur (thigh bone) articulating with the tibia (shin bone) is another example of a hinge joint.

    Ball-and-Socket Joint

    • Ball-and-socket joints are formed by the round end of one bone that articulates with a hollowed out end of another bone. These joints move in multiple directions: flexion/extension (bending and straightening), adduction/abduction (toward and away from the side), internal/external rotation (inward and outward rotation), horizontal adduction/abduction (across the body and away in the 90 degree horizontal plane). The hip and shoulder are examples of ball-and-socket joints.

    Pivot Joint

    • The pivot joint is formed by one bone that rotates around or next to another bone. The radius, or thumb-side forearm bone, forms a pivot joint with the ulna, the pinkie-side forearm bone. The radius rotates over the ulna when the forearm moves from a palm-up to a palm-down position.

    Saddle Joint

    • The saddle joint operates much like a saddle on a horse. It is comprised of a semi-circular bone that sits in a rounded out bone. It allows multiple movements to occur at a small joint. The base of the thumb is a saddle joint, and it can move clockwise, counter-clockwise, forward and back and away from and toward the hand.

    Other Joints

    • The hands and feet have multiple joint articulations occurring between numerous small bones. These joints include condyloid joints that allow motion in multiple directions and gliding joints that allow one bone to slide on the other. These joints are complex and intricate, and allow the hand and fingers to perform gripping and fine motor tasks.

Bones, Joints Muscles - Related Articles