Science & nature · Evidence-backed
10 Things to Know About the Clavicle
Understanding the clavicle helps explain shoulder mobility, upper‑limb strength and common injuries such as fractures. The following points distil key facts from trusted sources including peer‑reviewed anatomy references and national health services.
The clavicle, or collarbone, is a vital S-shaped bone linking the arm to the torso. This overview covers its anatomy, function, clinical relevance and healing process, drawing on authoritative anatomical and medical sources.
Length and shape of the clavicle
The clavicle, also known as the collarbone, is a slender, S-shaped long bone that measures approximately 15 centimetres (6 inches) in length. Its gentle curvature resembles an old‑fashioned key, which is reflected in its Latin name clavicula meaning 'little key'. This shape allows the bone to act as a stable strut between the shoulder blade and the breastbone while accommodating the dynamic movements of the arm.
Unique horizontal orientation
The clavicle is the only long bone in the human body that lies horizontally. This distinctive orientation sets it apart from other long bones such as the femur or humerus, which run vertically. The horizontal placement enables the clavicle to maintain the shoulder’s lateral position and to serve as a rigid link between the axial skeleton (sternum) and the appendicular skeleton (scapula).
Number of clavicles
Humans possess two clavicles, one on each side of the body. These paired bones mirror each other and together form the anterior component of the shoulder girdle. Their bilateral presence ensures symmetrical support for the arms and balanced distribution of mechanical loads during activities such as lifting, pushing or pulling.
Role as a strut between scapula and sternum
The clavicle functions as a strut that connects the scapula (shoulder blade) to the sternum (breastbone). By holding the scapula laterally away from the thorax, it preserves the shoulder’s range of motion and prevents the upper limb from collapsing toward the chest. This strut action is essential for efficient force transmission during arm movements.
Connection of the arm to the body
The clavicle connects the arm to the torso via ligaments that attach to the sternum and scapula. These ligamentous connections stabilise the shoulder joint while allowing the necessary freedom for elevation, rotation and abduction of the arm. Without this bony bridge, the upper limb would lack a firm anchor to the axial skeleton.
Main bony landmarks
The clavicle features three primary bony landmarks: the sternal end (medial), the shaft (central portion) and the acromial end (lateral). Each landmark serves a distinct purpose: the sternal end articulates with the sternum, the acromial end meets the scapula’s acromion, and the shaft provides a surface for muscle and ligament attachment. These landmarks are critical for joint stability and muscular leverage.
Functions of the landmarks
Each clavicular landmark contributes to shoulder mechanics. The sternal end forms the sternoclavicular joint, allowing elevation and rotation of the clavicle. The acromial end forms the acromioclavicular joint, facilitating scapular upward rotation during arm elevation. The shaft provides attachment sites for muscles such as the deltoid and trapezius, as well as ligaments that reinforce the joints and protect underlying neurovascular structures.
Shoulder mobility and force transmission
The clavicle enables free movement of the shoulder away from the body and transmits forces from the upper limb to the axial skeleton. When the arm lifts or bears weight, forces travel through the clavicle to the sternum and spine, distributing load and reducing stress on the shoulder joint. This mechanical role is vital for activities ranging from reaching overhead to carrying heavy objects.
Protection of neurovascular structures and heart
In addition to its mechanical functions, the clavicle shields the neurovascular bundle that supplies the upper limb, including the subclavian artery and vein and the brachial plexus. Together with the rib cage, it also helps protect the heart from anterior external impacts. This dual protective role underscores the bone’s importance beyond mere locomotion.
Key‑like rotation during arm movement
The clavicle rotates along its longitudinal axis like a key when the arms are moved away from the body. This slight torsional motion accommodates the changing geometry of the shoulder girdle during abduction and flexion, allowing smooth articulation at the sternoclavicular and acromioclavicular joints. The rotational capacity contributes to the bone’s durability under repetitive loading.
Every numbered claim above was required to carry source evidence before this topic could be published.