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M01.03.012 Clavicle
The clavicle, commonly known as the collarbone, extends between the manubrium of the sternum and the acromion of the scapula. As a long bone, it is easily palpable along its length and is often visible under the skin in thin individuals.
Key Functions of the Clavicle:
- Attachment: Connects the upper limb to the trunk as part of the shoulder girdle.
- Protection: Safeguards underlying neurovascular structures supplying the upper limb.
- Force Transmission: Transfers force from the upper limb to the axial skeleton.
This guide explores the bony landmarks, articulations, and clinical significance of the clavicle.
Bony Landmarks and Articulations
| Section | Description | Key Features |
|---|---|---|
| Sternal (Medial) End | Articulates with the manubrium of the sternum at the sternoclavicular joint. | – Large facet for articulation – Rough oval depression for the costoclavicular ligament. |
| Shaft | Acts as an origin and attachment site for various muscles. | – Muscles: Deltoid, Trapezius, Subclavius, Pectoralis Major, Sternocleidomastoid, Sternohyoid |
| Acromial (Lateral) End | Articulates with the acromion of the scapula at the acromioclavicular joint. | – Conoid tubercle: Attachment of the conoid ligament – Trapezoid line: Attachment of the trapezoid ligament |
Additional Notes:
- The clavicle has an “S” shape, with the medial section being convex and the lateral section concave.
- The coracoclavicular ligament suspends the weight of the upper limb from the clavicle.
Clinical Relevance: Fracture of the Clavicle
Common Causes:
- Falling onto the shoulder.
- Falling on an outstretched hand.
Distribution of Fractures:
| Location | Incidence |
|---|---|
| Lateral third | 15% |
| Middle third | 80% |
| Medial third | 5% |
Displacement After Fracture:
- Lateral end: Displaced inferiorly by the arm’s weight and medially by the pectoralis major.
- Medial end: Pulled superiorly by the sternocleidomastoid muscle.
Management:
| Type | Description |
|---|---|
| Conservative | Sling immobilization. |
| Operative | Open reduction and internal fixation. |
Note: Surgical repair may damage supraclavicular nerves, causing numbness in the upper chest and shoulder region.
Key Points to Remember
- Bony structure: The clavicle’s unique ‘S’ shape is crucial for its function and articulation.
- Muscle attachments: The clavicle serves as an anchor for multiple muscles critical to shoulder movement.
- Clinical importance: Fractures are common due to its role in force transmission, with most fractures occurring in the middle third.