The elbow is not a single joint but rather a complex made up of three distinct joints: the humeroulnar joint, the humeroradial joint, and the proximal radioulnar joint.
Breakdown of the Elbow Joints:
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Humeroulnar Joint: This is the main joint of the elbow, connecting the humerus (upper arm bone) to the ulna (one of the forearm bones). It primarily allows for flexion (bending) and extension (straightening) of the elbow.
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Humeroradial Joint: This joint connects the humerus to the radius (the other forearm bone). While it also contributes to flexion and extension, its primary role is to facilitate rotation of the forearm.
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Proximal Radioulnar Joint: This joint connects the radius and ulna near the elbow. It's crucial for pronation (turning the palm downwards) and supination (turning the palm upwards) of the forearm. The distal radioulnar joint at the wrist works in conjunction with the proximal radioulnar joint to achieve these movements.
Synovial Joints
All three of these joints are synovial joints. Synovial joints are characterized by a fluid-filled cavity that lubricates the joint, allowing for smooth movement. The synovial fluid reduces friction and nourishes the cartilage that covers the ends of the bones.
In summary, the elbow's functionality comes from the coordinated movement of these three synovial joints: the humeroulnar, humeroradial, and proximal radioulnar joints.
