The ulna (elle) is one of the two forearm bones. Both together connect the upper arm with the hand. More about structure and possible diseases, read here!


The ulna (Elle) is one of the two forearm bones. The other is the radius (spoke). Together, they connect the humerus with the carpal bones and are involved in the movements of the forearm against the upper arm and the hand against the forearm. Read all about the Ulna!

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  • What is the ulna?

  • What is the function of the ulna?

  • Where is the Ulna?

  • What problems can the ulna cause?

What is the ulna?

The Ulna (Elle) is a tubular bone, which is parallel to the radius (spoke) and is connected to this via a strong membrane of tight connective tissue. One differentiates at the Ulna three ranges: the Shank (Corpus) as well as one upper (proximal) and a lower (distal) end.

The shaft of the ulna is about the same thickness as the radius. It is triangular in cross-section, but is roundish toward the bottom (in the direction of the wrist). At the upper end of the ulna is much stronger than at the bottom, because the joint from upper to lower arm takes place primarily on the ulna. The joint between the forearm and the hand, however, takes place mainly on the radius, which is why the yard is less strong here.

At the upper (proximal) end of the ulna is a crescent-shaped, cartilaginous cutout (incisura trochlearis), which receives the articular role of the humerus (humeral trochanter). This neckline ends at the back with the elbow bump (olecranon) and at the front with the cortical process (coronoid process). This has laterally - towards the radius - a cartilage-covered cavity (Incisura radii), in which the radial head (Caput radii) engages. On the other side of this bony process, pointing to the middle, are two muscles: the superficial flexor (flexor digitorum superficialis), which bends the 2nd to 5th fingers in the middle and the metatarsophalaris and, to a lesser extent, the elbow joint, and the round inward pronator (pronator teres), which flexes the forearm and turns the palm downwards.

The posterior surface of the elbow bump (olecranon) lies just below the skin and is protected by a bursa (Bursa olecrani). The upper surface is the attachment for the three-headed arm muscle (triceps brachii), the only extensor muscle of the forearm. Below the cortical processus, the brachial phalanx sets in.

The shaft of the ulna serves in the upper and middle area as an approach for the deep finger flexor (flexor digitorum profundus), which bends the 2nd to 5th finger in the middle, ground and end joint. In the lower quarter springs the square inward-turning (pronator quadratus), which turns the palm downwards. In addition to the deep finger flexor, two other muscles attach to the back edge of the ulna: the ulnar flexor carpi ulnaris, which flexes the wrist and pulls it outward, and the ulnar extensor carpi ulnaris, which holds the hand with the hand The back of the hand pulls upwards and outwards.

The outward-facing edge of the ulna gives rise to the Supinator - a strong muscle that turns the palm of your hand upwards. At the back of the ulna, the anterior portion of the anterior canalis muscle (Anconaeus), which tightens the joint capsule and prevents it from becoming trapped. The sideward edge of the bone serves as a starting point for other muscles: the long thumb puller (abductor pollicis longus), which spreads the thumb, the short extensor pollicis longus, which stretches the thumb, and the forefinger extensor (Extensor indicis) The index finger and the hand stretches and in the wrist turns slightly upwards.

The condyle (caput ulnae) at the lower (distal) end of the ulna ends in the styloid process (styloid process), which communicates with the wrist via a cartilaginous disc (Discus articularis or triangularis) and carries ligaments.

What is the function of the ulna?

The function of the ulna consists in the connection of the humerus with the wrist - together with the tightly connected via a membrane radius. The variety of muscles that attach to the ulna allow flexion in the elbow and wrist as well as in the fingers, turning the palm in and out, stretching and flexing the hand, and spreading the hand outward.

Where is the Ulna?

The ulna is one of the two long bones that connect the lower end of the upper arm with the carpal bones and thus with the hand.

What problems can the ulna cause?

The ulna can break in any section, such as the Olecranon (Olecranon Fracture).

In ulna plus version the ulna is injury-related or congenital longer than the spokes, in the ulna-minus variant shorter.

The bursa at the proximal end of the ulna (Bursa olecrani) may catch fire, either as a result of open injury or permanent mechanical stress (desk work).

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