What is the elbow?
The elbow is a compound joint involving three bones – the humerus (upper arm bone) and the radius (radius) and ulna (ulna). More precisely, it is three partial joints with a common joint cavity and a single joint capsule that form a functional unit:
- Articulatio humeroulnaris (joint connection between the humerus and ulna)
- Articulatio humeroradialis (joint connection between the humerus and radius)
- Articulatio radioulnaris proximalis (joint connection between ulna and radius)
The elbow joint is held by collateral ligaments on the inside and outside.
The most important nerves and blood vessels run along the flexor side of the joint – when taking blood samples, the doctor pricks a vein in the crook of the elbow.
What is the function of the elbow?
The elbow enables flexion and extension of the forearm against the upper arm. Furthermore, the hand can be turned outwards (palm upwards) or inwards (palm downwards) by rotating the joint. In the first movement (supination), the radius and ulna bones are parallel to each other; in the second movement (pronation), they are crossed. The hinge joint between the humerus and ulna interacts with the other two joints to enable a wheel movement – the rotation of the forearm against the humerus.
The arm flexor (brachialis), which lies under the biceps, also flexes in the elbow joint.
The brachioradialis muscle is an important arm flexor that is used particularly when lifting and carrying heavy loads.
The arm extensor (triceps brachii) is the only extensor muscle at the elbow. As the three flexor muscles have a stronger tone at rest than the extensor muscle, the forearm is always in a slightly flexed position when we let it hang loosely.
Where is the elbow located?
The elbow is the articulated connection between the upper arm bone and the two forearm bones.
What problems can the elbow cause?
An elbow fracture usually occurs when a person falls on their outstretched hand. The fracture line can be at different points in the area of the joint, i.e. the term elbow fracture covers all fractures of the upper arm, ulna or radius near the elbow joint. This includes, for example, the olecranon fracture (fracture of the end of the ulna on the elbow side).
The elbow joint can also dislocate. This dislocation usually occurs in the humeroulnar joint, i.e. the partial joint between the humerus and ulna. The cause is usually a fall on the outstretched or slightly bent arm.
A bursa close to the joint can become painfully inflamed (bursitis olecrani). Sometimes bacteria are the cause. In other cases, it is an abacterial inflammation, such as can occur in the context of rheumatoid arthritis or gout. Chronic pressure due to frequent leaning on the elbow (“student’s elbow”) can also be the trigger for abacterial bursitis.
