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The shoulder girdle consists of the clavicle and scapula, articulating with the sternum and the upper limb.
The sternoclavicular (SC) joint is the only true bony articulation between the upper limb and the axial skeleton.
It is a saddle-type synovial joint, functioning almost like a ball-and-socket joint because of its wide range of movement.
Saddle-type synovial joint with an articular disc dividing it into two separate cavities.
Functionally behaves like a ball-and-socket joint.
Medial end of clavicle: Large and convex vertically.
Clavicular notch of manubrium sterni: Concave vertically.
Cartilage of 1st costal cartilage: Completes the articular cavity below.
Fibrocartilaginous, attached:
Above: Superior aspect of clavicle.
Below: 1st costal cartilage.
Periphery: To fibrous capsule.
Function:
Acts as shock absorber between upper limb and axial skeleton.
Divides joint into two synovial cavities, allowing independent movement.
| Ligament | Attachments | Function |
|---|---|---|
| Anterior & Posterior Sternoclavicular | From manubrium to clavicle anteriorly and posteriorly | Strengthen capsule |
| Interclavicular | Between sternal ends of both clavicles across jugular notch | Prevents excessive depression of clavicle |
| Costoclavicular (Rhomboid) Ligament | From upper surface of 1st costal cartilage to inferior surface of clavicle | Limits elevation of clavicle; strongest ligament of joint |
Encloses the joint completely.
Loose, permitting free mobility.
Lined by synovial membrane on both compartments (above and below the articular disc).
Anterior: Sternomastoid, sternohyoid, sternothyroid muscles.
Posterior: Large veins — internal jugular and brachiocephalic.
Inferior: First rib and pleura.
Branches from:
Internal thoracic artery
Suprascapular artery
Inferior thyroid artery
Medial supraclavicular nerve (C3, C4).
Nerve to subclavius (C5, C6).
Although small, the SC joint allows movement of the clavicle, which transmits motion to the entire upper limb.
| Movement | Axis / Plane | Muscles Producing Movement |
|---|---|---|
| Elevation | Coronal axis | Trapezius, sternocleidomastoid |
| Depression | Coronal axis | Subclavius, pectoralis minor |
| Protraction (forward) | Vertical axis | Serratus anterior |
| Retraction (backward) | Vertical axis | Trapezius, rhomboids |
| Rotation (axial twist) | Long axis of clavicle | Full shoulder elevation and rotation of scapula |
Strong ligaments, particularly the costoclavicular ligament.
Articular disc resists displacement.
Subclavius muscle acts as dynamic stabilizer.
Rare due to strong ligaments.
Anterior dislocation more common than posterior.
Posterior dislocation can compress trachea or great vessels — medical emergency.
May occur in contact sports or falls.
Presents with pain, swelling, and limited shoulder motion.
Treated conservatively with immobilization.
Seen in elderly and heavy manual workers.
Pain at upper sternum aggravated by shoulder elevation.
All shoulder movements are transmitted through this joint → restriction here limits full abduction of limb.
Place the body supine with the upper limb by the side.
Make a transverse incision across the upper chest at the level of the sternal ends of clavicles.
Reflect the skin and superficial fascia to expose:
Sternocleidomastoid (attached to clavicle and manubrium).
Pectoralis major (arising from clavicle).
Carefully clean the capsule and surrounding ligaments:
Identify anterior & posterior sternoclavicular ligaments.
Trace interclavicular ligament across jugular notch.
Expose costoclavicular ligament below.
Open the capsule → note articular disc dividing the joint cavity into upper and lower compartments.
Demonstrate articular surfaces on medial clavicle, manubrium, and 1st costal cartilage.
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