Clavicle: Encyclopedia - Clavicle

Clavicle

In human anatomy, the clavicle or collar bone is a bone that makes up part of the shoulder girdle (pectoral girdle).

Clavicle - Overview

It is a doubly-curved long bone that connects the arm (upper limb) to the body (trunk), located directly above the first rib. Medially, it articulates with the breast-bone (sternum) at the sternoclavicular joint. At its lateral end it articulates with the acromion of the shoulder-blade (scapula) at the acromioclavicular joint. It is shorter, thinner, less curved, and smoother in women than in men.

Clavicle - 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 maxiumum 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.

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.

Clavicle - Attachments

Muscles and ligaments that attach to the clavicle include:

• Deltoid muscle at the deltoid tubercle on the superior surface
• Subclavius muscle at the subclavian groove on the inferior surface
• Conoid ligament (the medial part of the coracoclavicular ligament) at the conoid tubercle on the inferior surface
• Trapezoid ligament (the lateral part of the coracoclavicular ligament) at the trapezoid line on the inferior surface

Clavicle - Development

The clavicle is the first bone to begin the process of harderning (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.

Clavicle - Common Clavicle Injuries

• acromioclavicular dislocation
• sternoclavicular dislocations
• clavicle fractures
• osteolysis
• degeneration of the clavicle

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

Please visit the anatomical position page for more detailed information.

See also

• Bone terminology
• Terms for anatomical location

Adapted from the Wikipedia article "Clavicle", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki