Synonyms
Medical: Articulatio cubiti
Definition
The elbow joint (Articulatio cubiti) connects the upper arm with the forearm. It consists of three partial joints, which are formed by three bones (upper arm, ulna and radius): These partial joints are combined with a common joint capsule to form the elbow joint.
- Humeroulnar joint (Articulatio humeroulnaris): formed by upper arm (humerus) and ulna
- Humeroradial joint (Articulatio humeroradioalis): formed by upper arm and radius
- Proximal radioulnar joint (Articulatio radioulnaris proximalis): formed by the proximal (near body) ends of ulna and radius
Function
The elbow joint can be moved in two degrees of freedom. On the one hand, the forearm can be bent and stretched while the upper arm is not moving (flexion/extension). On the other hand, the elbow joint is functionally involved with the proximal radioulnar joint in rotational movements of the hand (pronation/supination).
The main movements in the elbow joint are performed by the muscles of the upper arm. The flexors are located at the front of the upper arm. These include: The extensors in the elbow joint are located at the back of the humerus. This includes: Individual muscles of the forearm are also involved in pronation and supination.
- The biceps brachii muscle (biceps)
- And the brachioradialis muscle (upper arm spoke muscle).
- The musculus triceps brachii (triceps).
Humeroulnar joint
In the humeroulnar joint (Articulatio humeroulnaris), the “roll” of the upper arm (Trochlea humeri) forms a joint with a corresponding depression on the ulna (Incisura trochlearis). The olecranon, a bony projection of the ulna that can be palpated as an “elbow”, is closely connected to the trochlear incisura. The humeroulnar joint enables flexion and extension (flexion and extension) and is therefore a so-called hinge joint.
Humeroradial joint
The humeroradial joint (Articulatio humeroradialis) is formed by the connection of the head of the humerus (Capitulum humeri) and the corresponding depression (Fovea articularis radii) on the head of the spoke (Radius head, Caput radii). This joint also has the two degrees of freedom of flexion/extension for flexion and extension of the forearm and supination/pronation for rotation of the hand. Strictly speaking, this is a ball joint. Ball joints always have three degrees of freedom (in addition to the degrees of freedom of the hinge joint, abduction and adduction). However, since the humeroradial joint is secured by very strong ligament connections, this last degree of freedom is omitted, so that anatomically it is a ball-and-socket joint which, however, only has two degrees of freedom.
