The 206 bones in the human body are divided into four basic types: long bones, short bones, irregular bones and flat bones. Flat bones are composed of two compact surfaces with a spongy bone layer in the middle. The clavicle bone, also called the collarbone, is a flat bone which attaches on one end to the sternum, or breastbone, and on the other end to the scapula, or shoulder blade.
There are actually two clavicle bones, one on each shoulder. The two clavicles and the two scapulas form the shoulder girdle, also called the pectoral girdle. The girdle functions as an attachment structure for the muscles which control the movement of the shoulder and elbow joints. It provides support for the shoulder and connects the arms to the rest of the skeleton.
The function of the clavicle is to keep the scapula in place, allowing the arm maximum range of motion. It protects several blood vessels in the shoulder region and helps to deflect the force from physical impact to other areas of the skeleton. It also serves as an attachment place for several muscles including the deltoid muscle, trapezius muscle, and subclavius muscle. Unlike most bones, the clavicle bone does not have marrow.
A fractured clavicle is one of the most common shoulder injuries. Babies can actually sustain a broken clavicle while passing through the birth canal during childbirth. The clavicle is the first bone to ossify, or harden, in the fetus, but does not completely ossify until early adulthood, making it more susceptible to injury. Clavicle fractures can be the result of a fall or blow to the shoulder and frequently occur in sports such as football, basketball and soccer.
Symptoms of a broken clavicle include pain, swelling, and difficulty moving the arm. The break can often be felt through the skin and is easily identified in an X-ray. Nerve and arterial damage rarely occurs as a result of the break, though the physician will generally check to make certain that no additional damage is present. In most cases, a fracture is treated non-surgically by immobilizing the arm with a sling or a figure eight brace. A figure eight brace pulls the shoulder back, forcing the clavicle into alignment.
The clavicle bone is one of the few bones which can develop a disorder called Paget’s disease. This condition causes the bone to undergo abnormal growth while becoming weaker. The prognosis for this disorder is generally good, and treatment is not required unless pain becomes an issue.
It is extremely unusual for tumors to develop in flat bones, especially in the clavicle. In rare cases, a benign tumor known as an aneurismal bone tumor may occur. Ewing’s sarcoma and hemangiopericytoma tumors may also appear in the clavicle.