The clavicle is a doubly-curved long bone the only horizontal long bone in the human 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 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. 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. 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. Template:Bones of upper extremity. Template:WikiDoc Sources. Overview Right clavicle - from below, and from above.
Left clavicle - from above, and from below. 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. List of Partners vendors.
The clavicle, also referred to as the collar bone, is an elongated, S-shaped bone that sits between the shoulder and sternum at the top of the ribcage. It provides structural support between the shoulder and rest of the skeleton, and is one of the most frequently fractured bones in the body. The clavicle joins the scapula , or shoulder blade, and sternum to form two joints on either end of the bone, which are:.
The relative size of the clavicle leaves it particularly susceptible to fracture. Fracture of the clavicle can occur from a fall landing on an outstretched hand or through a direct blow to the shoulder. The clavicle and scapula together are collectively referred to as the pectoral girdle , or shoulder girdle. The clavicle connects the shoulder to the rest of the skeleton.
Its positioning allows for increased range of motion of the shoulder away from the body and helps protect the arm by dispersing force transmitted through direct contact. The clavicle has a small degree of movement in elevation and depression upward and downward movement , protraction and retraction forward and backward movement , and rotation. It originates at the first rib, and attaches to the underside of the clavicle. When contracted, the subclavius, controlled by the subclavian nerve, causes the clavicle to depress, or move downwards.
The anterior deltoid, trapezius, sternocleidomastoid, and pectoralis major muscles all attach to the clavicle for support, and cause a small degree of multidirectional movement as well. The midclavicular line, a vertical line drawn down the body from the midpoint of the clavicle, serves as an important anatomical landmark for locating other structures, including the apex of the heart , where a stethoscope can be placed to listen to the heartbeat.
The clavicle and associated joints can become damaged from injury or repetitive overuse of the shoulder. Common conditions associated with the clavicle include the following. Trauma to the acromioclavicular joint, such as a direct blow to the front of the shoulder or falling and landing on an outstretched hand, can injure the ligaments holding the acromion and clavicle together.
This can result in either an acromioclavicular joint sprain or separation of the joint. Symptoms include pain localized specifically at the acromioclavicular joint at the top of the shoulder.
Injury to the shoulder, especially direct trauma to the front of the shoulder, can cause the clavicle to fracture. Symptoms include pain at the clavicle and shoulder, as well as pain and difficulty with moving the arm. The sternoclavicular joint, between the clavicle and sternum, can become dislocated with injury to the front of the shoulder, causing pain and swelling around the injured area.
The end of the clavicle, or distal portion, that forms the acromioclavicular joint can become irritated and inflamed. Osteolysis, or bone degeneration, can easily occur at the end of the clavicle due to the high degree of stress and repetitive forces placed through the small surface area of the acromioclavicular joint, especially with heavy lifting such as bench press or military press.
The bone begins to break down at a faster rate than it is able to heal and form new bone cells. Sharp pain commonly occurs with overhead and pushing movements of the arm and shoulder with a dull ache at rest. Aging and repetitive overuse of the shoulder can lead to degeneration of the cartilage and the development of arthritis within the acromioclavicular joint, causing inflammation within the shoulder and pain with arm movements.
Depending on the extent of your condition, rehabilitation for conditions associated with the clavicle or associated joints include the following:. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Hansen, JT. Chapter 7; Upper Limb.
In Hansen JT, ed. American Academy of Orthopedic Surgeons. Clavicle Fracture Broken Collarbone. Updated December Harvard Medical School.
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