Elbow joint

The elbow joint (art cubity) is formed by three bones: the humerus, the radial and the ulnar. Bones form three joints, enclosed in a joint joint capsule.

1. The adenoid joint (art humeroulnaris) is block-shaped, formed by the connection of the humerus block and the block-shaped cutting of the ulna.
2. The humeroradial joint is an articulation of the head of the humerus and the joint cavity of the radius.
3. The proximal radiophobic joint (art radioulnaris proximalis) is cylindrical in shape, formed by the joint radius of the radius and radial cutting of the ulna. The joint joint capsule is free. On the humerus, the joint capsule is attached relatively high above the articular cartilage of the humerus block, so the coronary and radial fossa and the pit of the elbow are located in the joint cavity. The lateral and medial epicondyle of the humerus are located outside the joint cavity. On the ulna, the joint capsule is attached below the edge of the articular cartilage of the coronoid process and at the edge of the block-shaped notch of the ulnar process. On the radius, the capsule is attached to its neck.

The joint capsule is strengthened with ligaments.

The ulnar collateral ligament (lig. Collaterale ulnare) originates below the edge of the medial epicondyle of the humerus, widens out in a fan-shaped manner and is attached throughout the medial margin of the block-shaped notch of the ulna.

Radial collateral ligament (lig. Collaterale radiale), starting at the lower edge of the lateral epicondyle of the humerus, is divided into two fascicles. The front fascicle covers the radial cervix in front and is attached to the anterior margin of the blocky ulnar bone. The posterior fascicle of this ligament covers the cervix of the radial bone from behind and is weaved into the annular bundle of the radius.

The annular radial ligament (lig. Annulare radii) begins at the anterior edge of the radial incision of the ulna, envelops the neck of the radius in the form of a loop and is attached to the posterior edge of the radial notch. Between the distal edge of the radial notch of the ulna and the neck of the radius is a square ligament (lig. Quadratum).

In the elbow joint movements around the frontal axis are possible - flexion and extension of the forearm with a total volume of up to 170 °. When flexing the forearm slightly deviates medially and the brush does not lie on the shoulder, but on the chest. This is due to the presence of a notch on the block of the humerus, which contributes to the screw-like displacement of the forearm and hand. Around the longitudinal axis of the radius in the proximal radiophobic joint, the radial bone is rotated along with the brush. This movement takes place simultaneously in the proximal and distal ray-elbow joints.

With the X-ray of the elbow joint in the lateral projection (the forearm is bent by 90 °) the line of the x-ray joint gap is limited by a block-shaped incision of the ulna and the head of the radius bone on one side and the condyle of the humerus, on the other. With a direct projection, the X-ray joint gap is zigzag, 2-3 mm in thickness. The articular fissure of the proximal radiophilic joint is also visible.

The forearm bones are connected by means of discontinuous and continuous joints. A continuous joint is the interosseous membrane of the forearm (membrana interossea antebrachii). It is a strong connective tissue membrane stretched between the intercostal edges of the radial and ulnar bones. A fibrous, heavy chord (chorda obliqua) is seen from the proximal radioclavicular joint between both bones of the forearm.

Discontinuous compounds include the proximal fibroblast joint and the distal radiovolume joint, as well as the hand joints.

The distal radiovelone joint (art radioulnaris distalis) is formed by the joint of the joint ulnar bone and the elbow cutting of the radius. This joint is separated from the wrist joint by an articular disc (discus articularis) located between the elbow of the radius and the styloid process of the ulna. The joint capsule of the distal radiovolume joint is free, attached to the edge of the articular surfaces and the joint disc. The capsule usually protrudes proximally between the bones of the forearm, forming a bag-shaped recessus (recessus sacciformis).

The proximal and distal radioclavicular joints function together to form a combined cylindrical joint with a longitudinal axis of rotation (along the forearm). In these joints, the radial bone, along with the brush, rotates around the ulna. In this case, the proximal epiphysis of the radius is rotated in place, since the head of the radius is held by the annular bundle of the radius. The distal epiphysis of the radial bone describes an arc around the head of the radius, which remains fixed. The average range of rotation in the radiation-elbow joints (supination and pronation) is approximately 140 °.

Movement of the forearm in the elbow joint. The range of motion (flexion-extension) around the front axis is 150 °. Rotation of the radial bone along with the brush around the longitudinal axis of the forearm (pronation and supination) - 90-150 °. The movements in the elbow joint are performed by the following muscles.

Flex the forearm: the brachial muscle, the biceps arm muscle, the round pronator.

Unbend the forearm: the triceps brachium muscle, the elbow muscle.

Turn the forearm inward (pronation): the muscle is a round pronator, a square pronator.

Turn the forearm outward (supination): the supine muscle, the biceps arm muscle.

[1], [2], [3], [4], [5]