The collar bone is a long, slender bone that connects the arm to the trunk of the body. It is a fundamental component of the shoulder girdle, serving as the sole bony link between the upper limb and the axial skeleton. Due to its position and function, the clavicle is one of the most frequently fractured bones in the human body. This provides insight into how the shoulder complex moves and functions.
Structure and Location
The clavicle lies horizontally across the top of the chest, just above the first rib. This bone possesses a distinct double-curve, often described as an S-shape, which gives it mechanical resilience. The clavicle is divided into a medial end, a shaft, and a lateral end, and it is easily palpable along its entire length.
The rounded medial end connects to the sternum, forming the sternoclavicular joint. Providing the only true bony articulation between the upper limb and the main skeleton, the flatter lateral end connects to the acromion, a projection of the scapula (shoulder blade), at the acromioclavicular (AC) joint. These two articulation points allow the shoulder to move through an extensive range of motion.
Primary Role in the Body
The primary function of the clavicle is to act as a rigid strut, holding the scapula and the arm away from the ribcage. This separation is crucial, as it allows the shoulder to move freely, maximizing the range of motion available to the upper limb. Without this bony support, the shoulder would collapse medially toward the chest.
The clavicle also plays a significant role in force transmission, effectively relaying physical impacts from the arm to the central axial skeleton. Its position serves a protective function, arching over and shielding the underlying neurovascular structures that travel to the arm. These structures include the subclavian artery and vein, as well as the delicate network of nerves known as the brachial plexus.
Common Injuries and Healing
The clavicle is highly susceptible to injury, with fractures commonly resulting from a fall directly onto the shoulder or onto an outstretched hand. Approximately 80% of clavicle fractures occur in the middle third of the bone, where the S-curve is most pronounced and the bone is thinnest. In many cases, these fractures are treated non-surgically using a sling or immobilizer to keep the bone fragments aligned while they heal.
Healing times vary with age. For adults, a clavicle fracture takes between six and sixteen weeks to fully consolidate. Children under eight years old heal faster, often in three to six weeks, while infants can heal in as little as two weeks. Though most fractures heal completely, some patients may experience a visible lump at the fracture site, and full recovery often requires physical therapy.