Classification
- Type: Synovial saddle (functionally behaves as a ball-and-socket due to the intra-articular disc)
- Degrees of freedom: 3 (elevation/depression, protraction/retraction, rotation)
- Region: Shoulder complex (along with the acromioclavicular, glenohumeral, and scapulothoracic articulations)
Articular Surfaces
- Medial end of the clavicle (convex superiorly/inferiorly, concave anteriorly/posteriorly): The medial clavicular surface is larger than the sternal facet, resulting in less than half the clavicle articulating with the sternum at any given time. Covered with fibrocartilage rather than hyaline cartilage — an adaptation to the compressive and shearing forces at this joint.
- Clavicular notch of the manubrium (reciprocally shaped): A small, shallow facet on the superolateral manubrium. Also covered with fibrocartilage.
- Intra-articular disc: A fibrocartilaginous disc divides the joint into two separate compartments, improving congruence and acting as a shock absorber. The disc attaches superiorly to the clavicle and inferiorly to the first costal cartilage and manubrium. It prevents medial displacement of the clavicle and is the primary structure resisting superior migration of the medial clavicle.
Movements and ROM
Clavicular motion is essential for full shoulder elevation. The SC joint contributes approximately 40° of elevation and 35° of rotation during full arm elevation. Loss of SC mobility directly limits overhead reach.
Capsular Pattern
Pain at extremes of range (full elevation and full horizontal adduction)
The SC joint capsular pattern is less clearly defined than the GH or tibiofemoral patterns. Capsular restriction presents as pain and stiffness at the extremes of all movements rather than a proportional restriction ratio.
Resting Position
- Arm resting at the side, neutral shoulder position
- Capsule is most relaxed with minimal tension on all ligaments
Close-Packed Position
- Full arm elevation (maximum clavicular rotation and elevation)
- All ligaments taut, disc compressed, maximum congruence
End-Feels
| Movement |
Normal End-Feel |
Type |
| Elevation |
Capsular (firm) |
Costoclavicular ligament and inferior capsule limit further motion |
| Depression |
Capsular (firm) |
Interclavicular ligament and superior capsule; may become bony if the clavicle contacts the first rib |
| Protraction |
Capsular (firm) |
Posterior SC ligament and costoclavicular ligament |
| Retraction |
Capsular (firm) |
Anterior SC ligament and anterior capsule |
Ligaments
Anterior Sternoclavicular Ligament
- Attachments: Anterior surface of the medial clavicle → anterior manubrium
- Function: Resists anterior displacement of the clavicle. Relatively weak — most anterior dislocations tear this ligament.
- Injury mechanism: Direct posterior force on the lateral shoulder (e.g., falling onto the point of the shoulder)
- Assessment test: Palpation for tenderness and step-off deformity at the SC joint; observe for anterior prominence of the medial clavicle
- Condition link: Anterior SC dislocation (more common but less dangerous than posterior)
Posterior Sternoclavicular Ligament
- Attachments: Posterior surface of the medial clavicle → posterior manubrium
- Function: The strongest SC ligament — primary restraint against anterior and superior displacement. Resists retraction and medial displacement of the clavicle.
- Injury mechanism: High-energy trauma — direct anterior force on the medial clavicle driving it posteriorly. Posterior SC dislocation is a medical emergency because the medial clavicle can compress the trachea, esophagus, great vessels, or brachial plexus.
- Assessment test: Observe for posterior depression of the medial clavicle, dysphagia, dyspnea, or upper extremity vascular compromise — refer immediately if posterior dislocation is suspected
- Condition link: Posterior SC dislocation (rare but potentially life-threatening)
Costoclavicular Ligament
- Attachments: Superior surface of the first rib and its costal cartilage → inferior surface of the medial clavicle (the costal tuberosity)
- Function: The primary stabilizer of the SC joint. Resists elevation, depression, protraction, and retraction — acts as a fulcrum for clavicular motion. The clavicle pivots on this ligament during elevation and depression.
- Injury mechanism: Rarely injured in isolation. Hyperabduction or extreme clavicular elevation can sprain it. Chronic repetitive stress can produce costoclavicular syndrome (a component of thoracic outlet syndrome) where this ligament and the subclavius muscle compress the subclavian vessels and brachial plexus.
- Assessment test: Costoclavicular maneuver (military brace position — shoulders retracted and depressed — compresses structures between clavicle and first rib; positive = reproduction of neurovascular symptoms)
- Condition link: conditions/thoracic-outlet-syndrome
Interclavicular Ligament
- Attachments: Superior medial end of one clavicle → superior medial end of the opposite clavicle, spanning across the jugular notch of the sternum
- Function: Resists excessive depression of the clavicle. Connects the two SC joints as a stabilizing bridge.
- Injury mechanism: Rarely injured clinically. Torn in severe SC disruptions.
Mobilization Techniques
Hands-on instruction is required. The descriptions below provide clinical reference detail for understanding and supervised practice. They are not a substitute for instructor-led technique training. Correct hand placement, force dosage, and tissue response interpretation require hands-on coaching and feedback.
Convex-Concave Rule at the SC Joint
The SC joint has a saddle configuration — the clavicle is convex superiorly/inferiorly and concave anteriorly/posteriorly. For elevation/depression, the convex clavicular surface moves on the concave sternal facet, so the glide is
opposite to the restricted movement. For protraction/retraction, the concave surface moves on the convex, so the glide is in the
same direction as the restriction.
| Restricted Movement |
Glide Direction |
Reasoning |
| Elevation |
Inferior (caudal) glide |
Convex on concave → glide opposite → inferior |
| Depression |
Superior (cephalad) glide |
Convex on concave → glide opposite → superior |
| Protraction |
Anterior glide |
Concave on convex → glide same → anterior |
| Retraction |
Posterior glide |
Concave on convex → glide same → posterior |
General Contraindications (All SC Mobilizations)
- Absolute: SC joint instability or dislocation (especially posterior dislocation — medical emergency), acute fracture of the medial clavicle, active joint infection, RA with pannus, malignancy
- Relative: Osteoporosis (Grade I–II only), joint hypermobility, recent clavicle fracture (even if healed — confirm with imaging)
- Proximity caution: The trachea, esophagus, subclavian vessels, and brachial plexus lie immediately posterior to the SC joint. Never apply forceful posterior mobilization. Use gentle grades only.
Inferior (Caudal) SC Glide
Purpose: Restores clavicular elevation. Stretches the superior capsule and interclavicular ligament. Indicated when overhead reaching is limited by SC stiffness.
Patient position:
- Supine on the treatment table
- Arm at the side in neutral
- Head neutral or slightly rotated away from the treated side for better access
Hand placement:
- Stabilizing hand: Not needed — the manubrium is stabilized by the thorax and body weight against the table
- Mobilizing hand: Thumb or index finger pad placed on the superior aspect of the medial clavicle, as close to the joint line as possible. The thumb faces caudally.
Technique execution:
- Apply a slow, sustained or oscillatory force directed inferiorly (caudally, toward the patient's feet)
- Grade I–II: Very small amplitude oscillations — this is a small joint with vital structures posteriorly. Grade I–II is appropriate for pain modulation and initial assessment of joint play.
- Grade III–IV: Small amplitude oscillations into end-range inferior resistance. Use conservatively — the SC joint rarely requires aggressive mobilization.
- Rhythm: slow, 1 per second
- Duration: 20–30 seconds per set, 2–3 sets. Reassess clavicular elevation between sets.
Indications:
- Decreased clavicular elevation on accessory motion testing (compare bilaterally)
- Limited overhead elevation that persists after GH and scapulothoracic restrictions have been addressed
- Post-immobilization stiffness (clavicle fracture, post-surgical)
Technique notes:
- Common error: Excessive force — the SC joint is small and surrounded by critical structures. Use gentle pressures.
- Common error: Mobilizing posteriorly when intending to mobilize inferiorly — direction must be strictly caudal, not posterior.
- Reassessment: Re-test clavicular elevation and full arm elevation. Improvement confirms SC involvement.
Posterior SC Glide
Purpose: Restores clavicular retraction. Stretches the anterior SC ligament and anterior capsule. Indicated when scapular retraction is limited by anterior SC tightness.
Patient position:
- Supine on the treatment table
- Arm at the side
- Small towel roll between the scapulae to allow slight thoracic extension (opens the anterior chest)
Hand placement:
- Stabilizing hand: Not needed — the manubrium is fixed by thoracic contact with the table
- Mobilizing hand: Thumb pad placed on the anterior surface of the medial clavicle, just lateral to the joint line. Force directed posteriorly.
Technique execution:
- Apply a slow, sustained or oscillatory force directed posteriorly (toward the table)
- Grade I–II only in most cases. Due to the proximity of vital structures (trachea, esophagus, great vessels), posterior SC mobilization should be performed with extreme caution and kept to low grades.
- Grade III: Only if the clinician has confirmed that the restriction is capsular and no posterior instability exists. Never Grade IV at this joint in the posterior direction.
- Duration: 15–20 seconds per set, 2–3 sets
Indications:
- Decreased anterior-posterior accessory motion at the SC joint
- Anterior SC joint prominence (anterior subluxation — chronic, not acute)
- Restricted scapular retraction that does not improve with rhomboid/middle trapezius release
Technique notes:
- Critical caution: Posterior force at the SC joint pushes the medial clavicle toward the mediastinum. Use minimal force. If the patient reports throat tightness, difficulty swallowing, or arm numbness, stop immediately.
- Reassessment: Re-test scapular retraction and horizontal abduction.
Muscles Crossing This Joint
Muscles Attaching to the Medial Clavicle
- anatomy/muscles/sternocleidomastoid (clavicular head) — elevates the clavicle when acting from below; laterally flexes and rotates the head when acting from above
- anatomy/muscles/subclavius — depresses and stabilizes the clavicle; protects the subclavian vessels beneath the clavicle during fracture
- anatomy/muscles/pectoralis-major (clavicular head) — origin from the medial two-thirds of the clavicle
Muscles Affecting SC Motion Indirectly
Conditions Affecting This Joint
- conditions/thoracic-outlet-syndrome — the costoclavicular space (between clavicle and first rib) is a common compression site for the subclavian vessels and brachial plexus
- conditions/osteoarthritis — SC OA is common radiographically in older adults but is often asymptomatic; when symptomatic, presents as medial clavicle pain with overhead activities
- SC joint sprain — anterior dislocation (more common, visible anterior prominence) or posterior dislocation (rare, potentially life-threatening)
- Clavicle fracture — medial clavicle fractures are uncommon (most clavicle fractures occur at the middle third) but directly affect SC joint mechanics
Clinical Notes
- The SC joint is often overlooked in shoulder assessment. When GH and AC restrictions do not fully explain limited overhead motion, assess SC joint play. A hypomobile SC joint limits clavicular elevation and rotation, which caps total arm elevation regardless of GH mobility.
- Posterior SC dislocation is a medical emergency. The trachea, esophagus, subclavian artery and vein, and brachial plexus lie immediately posterior to the SC joint. If a patient presents with medial clavicle pain after trauma, dysphagia, dyspnea, or upper extremity vascular compromise — refer immediately. Do not attempt manual reduction.
- SC joint hypermobility in hypermobile populations. Patients with generalized joint hypermobility (Beighton score ≥4, EDS spectrum) often have visibly prominent and mobile SC joints. Mobilization is contraindicated — focus on stabilization exercises for the scapulothoracic musculature.
- SC joint degeneration is underappreciated. The SC joint begins degenerating as early as the third decade. By the fifth decade, disc degeneration is nearly universal. This is rarely symptomatic but can contribute to subtle overhead limitation attributed to the GH joint.
Key Takeaways
- The SC joint is the only bony connection between the upper extremity and axial skeleton — its mobility is prerequisite for full arm elevation.
- Posterior SC dislocation is a medical emergency (compression of trachea, great vessels) — always screen for posterior instability before mobilizing.
- The costoclavicular ligament is the primary stabilizer and serves as the fulcrum for clavicular motion — it is also a compression site in thoracic outlet syndrome.
- Always assess SC joint play when overhead limitation persists after GH and scapulothoracic restrictions have been addressed.
