AskDefine | Define collarbone

Dictionary Definition

collarbone n : bone linking the scapula and sternum [syn: clavicle]

User Contributed Dictionary

English

Noun

  1. The bone joining the shoulder and the breastbone.

Synonyms

Translations

the bone joining the shoulder and the breastbone

Extensive Definition

distinguish coloboma
This article uses some professional terms to describe relative positions and directions. See Anatomical terms of location for more detailed information.
In human anatomy, the clavicle or collar bone is classified as a long bone that makes up part of the shoulder girdle (pectoral girdle). It receives its name from the Latin clavicula ("little key") because the bone rotates along its axis like a key when the shoulder is abducted. (This movement is palpable with the opposite hand). In some people, particularly females who may have less fat in this region, the location of the bone is clearly visible as it creates a bulge in the skin.

Overview

The clavicle is a doubly curved short bone that connects the arm (upper limb) to the body (trunk), located directly above the first rib. It acts as a shunt to keep the scapula in position so the arm can hang freely. Medially, it articulates with the manubrium of the sternum (breast-bone) at the sternoclavicular joint. At its lateral end it articulates with the acromion of the scapula (shoulder blade) at the acromioclavicular joint. It has a rounded medial end and a flattened lateral end.
From the roughly pyramidal sternal end, each clavicle curves laterally and posteriorly for roughly half its length. It then forms a smooth posterior curve to articulate with a process of the scapula (acromion). The flat, acromial end of the clavicle is broader than the sternal end. The acromial end has a rough inferior surface that bears prominent lines and tubercles. These surface features are attachment sites for muscles and ligaments of the shoulder.

Functions

The clavicle serves several functions:
  • It serves as a rigid support from which the scapula and free limb are suspended. This arrangement keeps the upper limb (arm) away from the thorax so that the arm has maximum range of movement.
  • Covers the cervicoaxillary canal (passageway between the neck and arm), through which several important structures pass.
  • Transmits physical impacts from the upper limb to the axial skeleton.
Even though it is classified as a long bone, the clavicle has no medullary (bone marrow) cavity like other long bones. It is made up of spongy (cancellous) bone with a shell of compact bone. It is a dermal bone derived from elements originally attached to the skull.

Attachments

Muscles and ligaments that attach to the clavicle include:

Development

The clavicle is the first bone to begin the process of ossification (laying down of minerals onto a preformed matrix) during development of the embryo, during the 5th and 6th weeks of gestation. However, it is one of the last bones to finish ossification, at about 21-25 years of age. It forms by intramembranous ossification. It consists of a mass of cancellous bone surrounded by a compact bone shell. The cancellous bone forms via two ossification centres, one medial and one lateral, which fuse later on. The compact forms as the layer of fascia covering the bone stimulates the ossification of adjacent tissue. The resulting compact bone is known as a periosteal collar.

Additional images

Image:Pectoral girdle front diagram.svg|Pectoral girdle - front Image:Human arm bones diagram.svg|Human arm bones diagram

See also

References

  • Chung, Kyung. Board Review Series: Gross Anatomy, 4th edition.
  • Moore, Keith L. and Arthur F. Dalley. Clinically Oriented Anatomy, 4th edition.
  • Stedman's Medical Dictionary, 27th edition.
  • Mosby's Medical, Nursing, and Allied Health Dictionary, 5th ed.

External links

collarbone in Arabic: ترقوة
collarbone in Aymara: Qhiwi ch'aka
collarbone in Catalan: Clavícula
collarbone in Danish: Clavicula
collarbone in German: Schlüsselbein
collarbone in Estonian: Rangluu
collarbone in Spanish: Clavícula
collarbone in Esperanto: Klaviklo
collarbone in French: Clavicule
collarbone in Scottish Gaelic: Cnàmh an ugain
collarbone in Indonesian: Tulang selangka
collarbone in Italian: Clavicola
collarbone in Hebrew: עצם הבריח
collarbone in Latin: Clavicula
collarbone in Lithuanian: Raktikaulis
collarbone in Hungarian: Kulcscsont
collarbone in Dutch: Sleutelbeen
collarbone in Japanese: 鎖骨
collarbone in Norwegian: Kragebein
collarbone in Polish: Obojczyk (anatomia)
collarbone in Portuguese: Clavícula
collarbone in Russian: Ключица
collarbone in Slovak: Kľúčna kosť
collarbone in Slovenian: Ključnica
collarbone in Finnish: Solisluu
collarbone in Swedish: Nyckelben
collarbone in Tamil: காறை எலும்பு
collarbone in Thai: กระดูกไหปลาร้า
collarbone in Ukrainian: Ключиця
collarbone in Chinese: 锁骨
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