It is a complex joint that is located between the upper arm and the forearm. Allows flexion and extension of the latter with respect to the upper arm, as well as rotation of both the forearm and the wrist .
What is the elbow?
It is an articulation consisting of the ends of the humerus (in the upper part of the arm) and of the ulna and radius (in the forearm). Specifically, the end of the humerus is divided into two parts: the trochlea (on the inside) and the capital (externally). The first comes into contact with the ulna, while the second articulates with the radius.
The bony surfaces of the elbow are covered with a thin layer of cartilage . The joint is also surrounded by a capsule with function, at the same time, reinforcing and lubricating. In fact, the liquid produced by the synovial membrane of the capsule fills the empty spaces between the bones – reducing the friction forces – while the extensive network of ligaments that surround the capsule allow the elbow to maintain stability and to bear mechanical stress. . The radial and ulnar collateral ligaments connect and hold the radius and ulna in place, while the annular ligamentkeeps the bones of the forearm together. Taken together, they allow movement, avoiding the dislocation of the joint.
What is the elbow for?
It allows flexion and extension movements of the forearm , with a range of action of about 180 °. It also allows the rotation of the radius , which – in turn – makes pronation and supination movements of the wrist and hand possible . Its movements are however very limited by the anatomy of the ulna and by the compression of the soft tissues that surround the joint during the flexion phase.
Many muscles also originate or enter near the elbow . Among these, six are included which control the extension phase of the hand and fingers; they can become so stressful that they trigger epicondylitis (also known as “tennis elbow”), a disorder that in many cases can be resolved by resting.