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The radius is named so because the radius (bone) acts like the radius (of a circle). It rotates around the ulna and the far end (where it joins to the bones of the hand), known as the styloid process of the radius, is [clarification needed] the distance from the ulna (center of the circle) to the edge of the radius (the circle). The ulna acts ...
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 .
Beneath the neck of the radius, on the medial side, is an eminence, the radial tuberosity; its surface is divided into: . a posterior, rough portion, for the insertion of the tendon of the biceps brachii.
De Quervain syndrome causes pain over the styloid process of the radius. [3] [4] This is due to the passage of the inflamed extensor pollicis brevis tendon and abductor pollicis longus tendon around it. [4] [5] The styloid process of the radius is a useful landmark during arthroscopic resection of the scaphoid bone. [6]
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.
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 end regions of a long bone; regions of secondary ossification. epi-+ physis, "on top of the growth part" physis (epiphyseal plate) Also known as the growth plate. In a long bone it is a thin disc of hyaline cartilage that is positioned transversely between the epiphysis and metaphysis. In the long bones of humans, the epiphyseal plate ...
The head of the radius is wider than the bone's neck, and, because the annular ligament embraces both, the radial head is "trapped" inside the ligament which thus acts to prevent distal displacement of the radius. [4] It helps to stabilise the proximal radial head, [6] and the radioulnar joint. [7]