An example of a hinge joint (uniaxial) with movement essentially limited to flexion and extension. The condyles
at the lower end of the humerus
in the upper arm articulate with the heads of both the radius
and the ulna
in the lower arm. Twisting movements of the lower arm (pronation
) are possible because the top end (the head) of the radius can rotate against the lower end of the humerus. Flexion of the elbow is achieved by action of the biceps
muscle, which shortens and bulges, a muscle often shown to advantage in the classic pose of the body builder. Extension involves the triceps muscle, and when fully extended the arm should be in a straight line — the elbow angle at 180 degrees. This joint can also hyperextend; this is much more common in females than in males. Another difference in females is that the lower arms tend to be bent slightly more outwards when extended at the elbow (valgus carrying angle), thus clearing the hips, which are broader than in men. The most common problems associated with the elbow are colloquially described as ‘tennis elbow’ or ‘golfer's elbow’. However, these are not really a dysfunction of the elbow joint itself, but arise from over-indulgence in the named activity, or some equivalent muscular effort. Over-activity, particularly if the sport is not practised regularly, can result in small tears of the fibres in the tendons
of muscles which are anchored at the lower end of the humerus (at the epicondyles
), resulting in inflammation in this region (epicondylitis
). Characteristically there is pain at this site which is aggravated by gripping or twisting movements. Treatment may involve a local injection of anti-inflammatory agents (steroids
William R. Ferrell
See also joints
el·bow / ˈelˌbō/ •
n. the joint between the forearm and the upper arm. ∎ the part of the sleeve of a garment covering the elbow. ∎ a thing resembling an elbow, in particular a piece of piping bent through an angle.•
v. [tr.] strike (someone) with one's elbow: one player had elbowed another in the face. ∎ [intr.] move by pushing past people with one's elbows: people elbowed past each other to the door. ∎ fig. get rid of or disregard (a person or idea) in a cursory and dismissive way: his new TV talk show was elbowed aside in the ratings war.PHRASES: up to one's elbows in inf. with one's hands plunged in (something): I was up to my elbows in the cheese-potato mixture. ∎ fig. deeply involved in (a task or undertaking).
elbow (el-boh) n.
the joint in the arm formed between the ulna and part of the radius and the humerus.