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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]
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.
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.
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.
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.
In more detail, the actions are, by joint: [13] Proximal radioulnar joint of the elbow – The biceps brachii functions as a powerful supinator of the forearm, i.e. it turns the palm upwards. This action, which is aided by the supinator muscle, requires the humeroulnar joint of the elbow to be at least partially flexed. If the humeroulnar joint ...
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.
The distal radioulnar joint (DRUJ) is a pivot joint located between the distal ends of the radius and ulna, which make up the forearm.Formed by the head of the ulna and the ulnar notch of the radius, the DRUJ is separated from the radiocarpal (wrist) joint by an articular disk lying between the radius and the styloid process of the ulna.