Learning Objectives

By the end of this section, you should be able to:

Describe the anatomical position and functions of the clavicle
Identify its major bony landmarks and articulations
Explain the mechanisms and clinical features of clavicular fractures

The clavicle (collarbone) is a slender, elongated bone that extends between the manubrium of the sternum medially and the acromion of the scapula laterally. It forms a key component of the shoulder girdle, linking the upper limb to the axial skeleton.

Classified as a long bone, the clavicle is easily palpable along its entire length and is often visible beneath the skin in thin individuals.

Functions of the Clavicle

The clavicle serves three primary functions:

Attachment – connects the upper limb to the trunk as part of the shoulder girdle
Protection – shields underlying neurovascular structures supplying the upper limb
Force transmission – transfers mechanical forces from the upper limb to the axial skeleton

Bony Landmarks and Articulations

The clavicle has a characteristic S-shaped curve. When viewed from anteriorly, its medial two-thirds are convex, while the lateral third is concave. Anatomically, it is divided into three regions: the sternal end, shaft, and acromial end.

Sternal (Medial) End

The sternal end is enlarged and bears a smooth articular facet for the manubrium of the sternum, forming the sternoclavicular joint.
On its inferior surface is a roughened oval impression for the costoclavicular ligament, which stabilises the sternoclavicular joint.

Shaft

The shaft of the clavicle provides attachment and origin for several muscles, including:

Deltoid
Trapezius
Subclavius
Pectoralis major
Sternocleidomastoid
Sternohyoid

These muscular attachments contribute to shoulder movement and stability.

Acromial (Lateral) End

The acromial end bears a small facet for articulation with the acromion of the scapula, forming the acromioclavicular joint.
Its inferior surface contains two important landmarks:
- Conoid tubercle – attachment of the conoid ligament (medial part of the coracoclavicular ligament)
- Trapezoid line – attachment of the trapezoid ligament (lateral part of the coracoclavicular ligament)

The coracoclavicular ligament is a strong stabilising structure that effectively suspends the weight of the upper limb from the clavicle.

Clinical Relevance

Fracture of the Clavicle

Due to its role in transmitting forces from the upper limb to the axial skeleton, the clavicle is particularly vulnerable to fracture. The most common mechanisms include:

A fall onto the shoulder
A fall onto an outstretched hand

When the clavicle is divided into thirds:

80% of fractures occur in the middle third
15% occur in the lateral third
5% occur in the medial third

Displacement Pattern

Following fracture:

The lateral fragment is displaced inferiorly by the weight of the upper limb and medially by the pull of the pectoralis major
The medial fragment is displaced superiorly by the sternocleidomastoid muscle

Management

Treatment may be:

Conservative – sling immobilisation and analgesia
Surgical – open reduction and internal fixation in selected cases

The supraclavicular nerves lie close to the clavicle and may be damaged or sacrificed during surgical repair, potentially resulting in a patch of numbness over the upper chest and shoulder.