Ulna

The ulna (Latin - anat. Elle ) is adjacent to the radius ( spoke) one of the two bones of the forearm. The cubit is the little-finger side of the slope, less vigorous than the spoke and a typical long bone.

The adjective ulnar means " belonging to Elle " or indication of direction " for Elle back ".

Top

Located at the center of the body ( proximal ) end of the ulna ( olecranon AltGr. Ὠλένη = ulna κράνος = helmet ) is considerably thickened and ends in a broad, beak-like solid bone spur that is called elbow bump (tuber olecranon ). Its posterior ( posterior ) surface is approximately triangular, smooth and of a bursa ( olecranon bursa ) covered, as it lies just beneath the skin. At the front edge of the bone spur can be seen a transverse depression serving the rear fiber tracts of the joint capsule of the elbow joint as an approach. The upper ( superior ) surface of the bone spur is approximately diamond-shaped and roughened where the tendon of the triceps brachii muscle strong ( triceps brachii ) radiates into the bone. The bone spur on the hook-shaped forward projecting elbow extension ( processus anconeus ) engages in extension of the elbow joint ( articulatio cubiti ) in the bone spur pit ( olecranon fossa ) of the upper arm bone ( humerus). On looking to the middle ( medial ) edge of the bone spur of the ulna head (caput ulnar ) side of elle Handbeugers ( flexor carpi ulnaris ) arises. On the side ( lateral ) edge of elbow muscle is where (musculus anconeus ). The front (anterior ) surface of the bone spur is smooth, curved inwards and covered by the articular cartilage. It forms the upper part of the articular surface, a groove for the joint role ( trochlear ), which is involved in the formation of the elbow joint. At the base of the bone spur encompass both sides of a lateral and directed to the middle coronoid process ( coronoid lateralis and medialis) the spoke head.

For large breeds, it may ( fractures) of the elbow extension or the centripetal Kronfortsatzes come at the elbow dysplasia in bone fractures.

Body

The middle section of the ulna is called Elle Elle body or shaft ( corpus ulnae ).

The Elle is on the forearm along with the spoke a functional unit. This becomes apparent inter alia anatomically that both bones coupled to one another in various ways. For one, they have at their facing the center of the body and away from the center of the body (distal) end of each hinged connection to each other and to the other almost the entire length spanned by a fairly stable adhesive tape between the two on ( interosseous membrane ). This relatively tight train is generated at the Elle at the spoke side directed toward an edge ( Margo interosseous ). This is the only sharp edge is, is therefore easily felt through the skin and is the same edge of the spoke opposite.

Also on the front and back of the yard you can each define an edge ( Margo anterior and posterior).

Despite his almost cylindrical body you can define at the Elle different surfaces at the edges due to the just described. The front surface ( Facies anterior) the bone located between the front edge surface and the edge lying between the two bones of the forearm. Between the front and rear edge there is also an area that is called directed to the middle surface (facies medialis). A back surface ( posterior surface ) is defined as the area that is defined by the rear edge and the edge between the two bones. This is the band's adhesion between the two bones as a source surface.

Bottom

The slightly broadened lower end of the ulna is ( ulna caput) as head of the ulna referred to and ends with the styloid process ( ulnar styloid ). This is clearly shown on the little finger side above the wrist more or less. The front - side lying articular surface area ( circumferentia articular ) is consistent with the notch ( sigmoid notch ) for the head of the ulna at the spoke and the cartilage-covered on the inside spokes ring band ( annular ligament of the radius ) in conjunction.

Adjacent joints

At the articulated connection of the forearm bone with the carpal bones (ossa carpi ), the Elle is no direct participation. You must bridge the emerging due to the further away from the body center link end distance with an articular disc ( articular disc ).

Ulna and radius have two hinged connections with each other. First, the nearest the center of the body ulnar joint ( radioulnar joint Proximal ), sometimes to the elbow joint ( articulatio cubiti ) is counted, and on the other the distal ulnar joint ( distal radioulnar joint ). These allow Umwendebewegung inwardly and outwardly of the spoke to the ulna ( pronation and supination ).

For animals that mainly perform walking motions (eg horse, ruminants), the ulna bone is fused with the spoke ( synostosis ) and so are the two bones against each other immobile.