What is the elbow?
The elbow is a complex hinge joint located between the upper part of the arm and the forearm. It allows the hand to be bended and moved towards or away from the body, as well as the wrist and forearm to be rotated. Elbow range of motion is vital for functional tasks such as grasping objects and writing.
The elbow is an articulation formed by three different portions enveloped by a common joint capsule: the humeroulnar joint, the humeroradial joint, and the superior radioulnar joint. Specifically, the humerus is divided into two parts: the trochlea and the internal and external capitulum. The first comes into contact with the ulna, while the second is articulated with the radius.
In the elbow joint, bones surfaces are covered by a thin layer of cartilage. The joint itself is surrounded by a capsule that averts dangerous friction during movement by lubricating its surfaces.
The synovial membrane of the elbow joint is very extensive. The liquid from the synovial membrane of the capsule can in fact fill the empty spaces between the bones, reducing friction forces, while the extensive network of ligaments which surround the capsule, help the elbow maintain stability and withstand any mechanical stress. The radial and ulnar collateral ligaments connect and keep the radius and ulna in place, while the annular ligament holds the bones of the forearm together. Combined, they allow range of movement of the elbow joint, while avoiding dislocation of the joint.
There are different types of diseases commonly associated with the elbow joint. Elbow pain can occur for a various number of reasons including tendonitis, fractures, dislocation, infection, arthritis, bursitis and other conditions. Seeking medical attention is essential in order to determine the most appropriate form of treatment, whether it is pain medications, wrist splints, physical therapy or even surgery. Effective use of the hands requires painless and stable elbow joints.
What function does the elbow serve?
The elbow permits flexion and extension of the forearm with a radius of movement of about 180 degrees. It also makes pronation and supination movements of the hand and wrist possible. Its range of movement, however, is restricted by its anatomy and compression of soft tissue surrounding the joint during flexion. By positioning the forearm to use a hand, the elbow’s key feature is to provide maximum stability.
A large amount of muscles originate near the elbow. Among these, six are included under the control of the hands and fingers. A common condition that occurs from the overuse of the hand and forearm, through chronic repetitive motion, is known as “tennis elbow” (or epicondylitis).The repetitions can injure the tendons that connect the extensor supinator muscles to the olecranon process and cause symptoms such as elbow pain, weakness and numbness. Rest is generally recommended as a non-invasive treatment option. Wearing a wrist brace may also be suggested in order to keep the wrist in flexion, as well as icing, ultrasound, steroid injections and compressions to help alleviate any pain. Further treatment, such as physical therapy, may be necessary in order to strengthen the muscles and prevent further complications from arising.
