Clavicle

The collarbone ( clavicle the Latin, Germanized also clavicle, AltGr. Κλείς, genitive κλειδός [ cleidos ] ) is one of the three original bones of the shoulder girdle in reptiles, birds and mammals. In teleosts, the clavicle is Hautverknöcherung as already indicated, in amphibians is lacking.

Word origin

Clavicle in latin means Ranke, particularly the winding shape of the bone even more reminiscent of a vine as a key (Latin Clavis ). The Greek name ( cleido ) comes therefore from a faulty transmission. This comes in the anatomy in similar form also in the sphenoid.

Comparative Anatomy

The long hand about the human clavicle is in some mammals regressed ( rudimentary ). Well developed, it is in humans, the other primates, generally in climbing animals, but also in rodents and lagomorphs. It is in its connection to the sternum ( sternoclavicular ) to the shoulder blade and the single pivotal connection of the upper extremity with the body.

In domestic cats, it is reduced to a stored into a muscle (musculus cleidocephalicus ) bone and is no longer with the scapula in an articulated connection. In many other mammals (eg, horse, cloven-hoofed animals, dog) is regressed to an embedded in these muscle tendon strip.

In birds the two clavicles are a V- shaped bone, the wishbone ( furcula ), fused, which holds the two shoulder joints apart as a tension spring while flying. Tribal History the wishbone makes its appearance in theropod dinosaurs for the first time. In the English-speaking cultural area of the bones is colloquially referred to as a "wishbone ". This name comes from the tradition of the Thanksgiving feast to pinch dried Furcula the turkey between the two small fingers of two people sitting opposite and pull on it. He whose piece of bone after fracture is the larger, has a wish ( wish ) free.

In addition to the clavicle, the coracoid ( coracoid ) and the shoulder blade are ( scapula ) to the shoulder girdle. In mammals, including humans, the coracoid is not a separate bone, but an extension of the scapula, as the coracoid process ( coracoid process ) is called.

Anatomy of the human clavicle

The clavicle of man is about 12-15 cm long and is S-shaped curved. It has two ends and a middle piece ( Corpus clavicle ). The directed towards the center of the body (medial ) end sternal ( breastbone hinz eigend ) called extremitas and has a round articular surface, articular facies sternalis, called the part of the joint between the chest and collarbone, articulation sternoclavicularis is. The lateral end is called extremitas acromial ( shoulder height hinz eigend ), forms a joint with the shoulder height ( acromion ), the acromioclavicular joint ( articulatio acromioclavicularis ), which is part of the shoulder blade. The corresponding articular surface of which is flattened in a saddle shape is called articular acromialis facies.

At the top of the clavicle to the deltoid is where ( deltoid muscle ). Through its strong train the bone surface is roughened. Medial to the bottom there is a depression for the ligamentum Impressio costoclavicular, which is caused by train of a band, the ligamentum costoclavicular.

At the bottom of the center piece there is a lateral groove, the sulcus musculi subclavii, wander through the subclavian muscle (musculus subclavius ​​). Also on the underside of the center piece is a constant nutricium hole formed foramen, through which passes a blood vessel for supplying the bone with oxygen and nutrients. There is a roughness tuberosity ligamentum coracoclavicularis, which can be further divided into a conoid tubercle and a Linea trapezoidea At the bottom of extremitas acromialis. In these structures, the coracoclavicular ligament inserted, which consists of two parts, the conoid ligament and the ligamentum trapezoid.

Diseases

In humans it can result in a fall on the shoulder, directly to the clavicle or rarely on the outstretched arm to fractures of the collarbone ( clavicle ). With about 15 % of all fractures clavicle breaks the second most. Symptoms include a visible and palpable the step, an apparent extension of the arm and changes in head position.

Klavikulektomie

The removal of the clavicle can be partial ( partial) or complete ( total). The partial Klavikulektomie is sometimes carried out at the ends in the area of ​​Schultereckgelenks or sternoclavicular joint, mainly in chronic instabilities or osteoarthritis. Usually only the small section near the joint is removed while the clavicle is otherwise receive.

For the complete Klavikulektomie all the bone is removed, which is why it comes to instability and a moderate loss of function of the shoulder and the affected arm. Cause are primarily malignant bone tumors, mostly osteosarcomas, Ewing sarcomas ( and Primitive neuroectodermal tumors and myeloma, but the clavicle is very rarely affected. Metastases do not occur in practice. Other very rare causes for a complete removal are chronic bone infections and complex bone fractures. removal is difficult and complications are common, in addition to local infection, especially violations of deeper structures, particularly the subclavian vein. a reconstruction of the clavicle is rarely performed since it is burdensome and with even higher complication rates and the removal of the clavicle only a moderate limitation in daily life brings with it.