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The ulna or ulnar bone (pl.: ulnae or ulnas) [3] is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the radius, the forearm's other long bone. Longer and thinner than the radius, the ulna is considered to be the smaller long bone of the lower arm.
The major exception is when the joint between these bones, the distal radioulnar joint (or DRUJ), is unstable. When the DRUJ is unstable, the ulnar styloid may require independent treatment. An excessively long styloid process of the ulna can cause painful contact with the triquetral bone in the wrist, known as ulnar styloid impaction syndrome. [1]
Note that this ligament is also referred to as the medial collateral ligament [1] and should not be confused with the lateral ulnar collateral ligament (LUCL). [ 2 ] The anterior portion , directed obliquely forward, is attached, above, by its apex, to the front part of the medial epicondyle of the humerus ; and, below, by its broad base to the ...
The deep muscles arise from the distal part of the ulna and the surrounding interosseous membrane. The brachioradialis , flexor of the elbow , is unusual in that it is located in the posterior compartment, but it is actually a muscle of flexor / anterior compartment of the forearm.
The distal radioulnar articulation [1] (also known as the distal radioulnar joint, [2] or inferior radioulnar joint [1] [3]) is a synovial pivot joint between the two bones in the forearm; the radius and ulna. It is one of two joints between the radius and ulna, the other being the proximal radioulnar articulation.
The accurate adaptation of the trochlea of the humerus, with its prominences and depressions, to the trochlear notch of the ulna, prevents any lateral movement. Flexion in the humeroulnar joint is produced by the action of the biceps brachii and brachialis , [ 3 ] assisted by the brachioradialis , with a tiny contribution from the muscles ...
In mammals and non-human primates, the pisiform is an enlarged and elongated bone that articulates with the distal ulna. [5] In some taxa, the pisiform even articulates with the hammate or radius. [5] In these non-human taxa, the pisiform develops from two ossification centers that are divided by a palmar epiphyseal plate. [5]
The elbow is a hinge joint with a rotatory component where the trochlea forms the convex, proximal surface which articulates with the concave, distal surface on the ulna, the trochlear notch. While the trochlea together with its associated fossae almost covers a 360° angle, the trochlear notch on the ulna forms a 190° arc and the gap in ...