Clavicle
Encyclopedia : C : CL : CLA : Clavicle
- Collarbone and collar bone redirect here. The eye abnormality is correctly spelt coloboma.
Contents
Overview
It is a doubly-curved long bone (the only horizontal long bone in the body) that connects the arm (upper limb) to the body (trunk), located directly above the first rib. 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 is shorter, thinner, less curved, and smoother in women than in men. It has a rounded medial end and a flattened lateral end.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 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 impacts from the upper limb to the axial skeleton.
Attachments
Muscles and ligaments that attach to the clavicle include:Superior surface:
- Deltoid muscle at the deltoid tubercle, anteriorly on the lateral third.
- Trapezius muscle posteriorly on the lateral third.
- Subclavius muscle at the subclavian groove
- Conoid ligament (the medial part of the coracoclavicular ligament) at the conoid tubercle
- Trapezoid ligament (the lateral part of the coracoclavicular ligament) at the trapezoid line
- Pectoralis major muscle on the medial third (rounded border)
- Deltoid muscle on the lateral third of border in the deltoid tubercle
- Sternocleidomastoid muscle superiorly, on the medial third (clavicular head of Sternocleidomastoid)
- Sternohyoid inferiorly, on the medial third
- Trapezius on the lateral third
Development
The clavicle is the first bone to begin the process of hardening (ossification) during development of the embryo, during the 5th and 6th weeks of gestation. However, it is the last of the long bones to finish ossification, at about 21 years of age. It forms by intramembranous ossification.Common clavicle injuries
- acromioclavicular dislocation
- sternoclavicular dislocations
- clavicle fractures
- osteolysis
- degeneration of the clavicle
Note about anatomical position
Note: this article uses some professional terms to explain certain anatomical details. These words apply only when the body is in anatomical position, i.e., standing with palms of the hands facing forward. These terms are:- superior - above
- inferior - below
- abduction - the movement of the limb away from the body
- medial - toward the midline
- lateral - away from the midline
See also
- Bone terminology
- Terms for anatomical location
- The collarbones are sometimes partly or completely absent in cleidocranial dysostosis
External links
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.
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.