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The proximal radioulnar joint is a synovial pivot joint. [1] It occurs between the circumference of the head of the radius and the ring formed by the radial notch of the ulna and the annular ligament. [2] The interosseous membrane of the forearm and the annular ligament stabilise the joint. [2]
The head of the radius has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum of the humerus.The circumference of the head is smooth; it is broad medially where it articulates with the radial notch of the ulna, narrow in the rest of its extent, which is embraced by the annular ligament.
Examples of a pivot joint include: Proximal radioulnar joint; Distal radioulnar joint; Median atlanto-axial joint; In contrast, spherical joints (or ball and socket joints) such as the hip joint permit rotation and all other directional movement, while pivot joints only permit rotation.
Therefore, the humeroradial joint is not functionally a ball and socket joint, although the joint surface in itself allows movement in all directions. The annular ligament secures the head of the radius from dislocation , which would otherwise tend to occur, from the shallowness of the cup-like surface on the head of the radius.
Humeroradial joint: head of the radius: capitulum of the humerus: Is a ball-and-socket joint. Superior radioulnar joint: head of the radius: radial notch of the ulna: In any position of flexion or extension, the radius, carrying the hand with it, can be rotated in it. This movement includespronation and supination.
The articulation between the radius and the ulna at the elbow is known as the proximal radioulnar joint. Distally, it articulates with the ulna again at the distal radioulnar joint. It forms part of the wrist joint by articulating with the scaphoid at its lateral aspect and with the lunate at its medial aspect.
Is a simple hinge-joint, and allows for movements of flexion and extension only. Humeroradial joint: head of the radius: capitulum of the humerus: Is a ball-and-socket joint. Proximal radioulnar joint: head of the radius: radial notch of the ulna: In any position of flexion or extension, the radius, carrying the hand with it, can be rotated in it.
It helps to stabilise the proximal radial head, [6] and the radioulnar joint. [7] Superiorly, the ligament is supported by attachments to the radial collateral ligament and the fibrous capsule of the elbow joint. Inferiorly, a few fibres attached to the neck of the radius support a fold of the synovial membrane without interfering with the ...