The clavicle is a bone found in the upper torso of of the human body. It is essential in providing support to the arm and shoulder. The clavicle is easily seen and touched in most people. The structure and function of the clavicle is interesting in that there is no other bone quite like it. The common term for the clavicle is the "collarbone" due to it's location around the collar.
Structure of the clavicle
The clavicle is very roughly "S" shaped (called "double-curved" to anatomists). It is stubby and about six inches in length. As with most bones in the body, the exact length can vary quite a bit from one person to another.
The clavicle is located just above and slightly in front of the first rib. The first rib is the top rib in the rib cage. In the chest wall, the clavicle attaches to a bone in the sternal area known as the manubrium. The manubrium is a small bone located just above the sternum. In most people, it is impossible to distinguish the sterum from the manubrium just by feeling for them.
On the shoulder side, the clavicle attaches with a part of the scapula known as the acromion. The scapula is also known as the shoulder blade. The acromion is a part of the scapula that sticks up and toward the front of the body. The joint formed at the junction of the clavicle and acromion is called, most appropriately, the acromioclavicular joint.
Interestingly, despite being classified as a "long bone", the clavicle does not have bone marrow, and thus is not involved in the production of blood cells.
Function of the clavicle
The clavicle has several important functions. The first function of the clavicle is to support the upper arm and scapula. Without a clavicle, your arm would have a tendency to get pulled in to the body. This would limit the range of motion of the arm and reduce its leverage and strength.
The clavicle also serves to protect several important blood vessels and nerves that pass below the bone and travel in to the arm. The brachial plexus is a group of nerves that lay behind the clavicle and are protected by it. These nerves control the arm.
The clavicle also serves as something of a "shock-absorber" for the upper torso. Physical contact from the side will be partially absorbed by the clavicle. Because of this function, the clavicle is a very commonly broken bone. Children are particularly at risk for breaking the clavicle (even the author of this article is article has a history of a clavicular fracture thanks to a fall during a game of "tag" in kindergarten.).
The clavicle is an important part of the shoulder joint. There are no fewer than six major muscles that attach to various parts of the clavicle. The deltoid, trapezius, and pectoralis major (chest) muscles are the most famous of these. All of these muscles are involved in support and movement of the arm, neck, back, and chest.
A last bit of interesting trivia regarding the clavicle involves its development in a fetus. The clavicle is the first bone to begin solidifying with calcium (usually as early as the 5th or 6th week of gestation). However, despite this early start, it is the last bone to finish calcifying.
The structure and function of the clavicle are important aspects to the bony anatomy of the human body. Without a properly functioning clavicle, your arm simply wouldn't work as well as it does.