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The radius is part of two joints: the elbow and the wrist. At the elbow, it joins with the capitulum of the humerus, and in a separate region, with the ulna at the radial notch. At the wrist, the radius forms a joint with the ulna bone. The corresponding bone in the lower leg is the tibia.
Type II: Notch is a blunted V-shape occupying the middle third of the superior border. Type III: Notch is U-shaped with nearly parallel margins. Type IV: Notch is V-shaped and very small. A shallow groove is frequently formed for the suprascapular nerve adjacent to the notch. Type V: Notch is minimal and U-shaped with a partially ossified ligament.
The olecranon is situated at the proximal end of the ulna, one of the two bones in the forearm. [1] When the hand faces forward the olecranon faces towards the back (posteriorly). It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa of the humerus during extension of the forearm. [2] [3]
Biceps is the major supinator (drive a screw in with the right arm) and pronator teres and pronator quadratus the major pronators (unscrewing) — the latter two role the radius around the ulna (hence the name of the first bone) and the former reverses this action assisted by supinator. Because biceps is much stronger than its opponents ...
The radius and scaphoid articulate deep to the snuffbox to form the basis of the wrist joint. In the event of a fall onto an outstretched hand (FOOSH), this is the area through which the brunt of the force will focus. This results in these two bones being the most often fractured of the wrist.
The radial notch of the ulna (lesser sigmoid cavity) is a narrow, oblong, articular depression on the lateral side of the coronoid process; it receives the circumferential articular surface of the head of the radius. It is concave from before backward, and its prominent extremities serve for the attachment of the annular ligament.
Lister's tubercle is found on the dorsal distal radius. [1] It varies in size and shape significantly. [2] [3] It can range from around 2 to 6 mm in height (averaging 3 mm), and around 6 to 26 mm in length (averaging 13 mm). [2] [3] Lister's tubercle consists of two peaks including radial peak and ulnar peak. [4]
A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a joint. The sesamoid bones protect tendons by helping them overcome compressive forces.