Topic Overview

📘 Facts to Remember – Joints of Upper Limb

General Concepts

• The upper limb joints are designed for mobility rather than stability — allowing a wide range of coordinated motion for prehension and manipulation.

• All major joints are synovial, with varying structural types (plane, hinge, pivot, saddle, ellipsoid, ball-and-socket).

• Hilton’s Law: Nerves supplying muscles acting on a joint also supply the joint and the skin over it.

1. Sternoclavicular Joint

• Only true bony connection between upper limb and trunk.

• Type: Saddle synovial joint (functionally ball-and-socket).

• Contains a complete articular disc dividing the cavity into two compartments.

• Ligaments: Anterior, posterior, interclavicular, and costoclavicular.

• Strongest ligament: Costoclavicular.

• Movement: Elevation, depression, protraction, retraction, rotation.

• Clinical: Dislocation is rare due to strong ligaments.

2. Acromioclavicular Joint

• Type: Plane synovial joint.

• Contains incomplete fibrocartilaginous disc.

• Chief stabilizer: Coracoclavicular ligament (conoid + trapezoid parts).

• Movement: Gliding and rotation between clavicle and scapula.

• Clinical: Complete rupture → “step deformity” (shoulder separation).

3. Shoulder (Glenohumeral) Joint

• Type: Ball-and-socket synovial joint — most mobile in the body.

• Articular surfaces: Head of humerus and glenoid cavity with labrum.

• Capsule: Loose, attached to glenoid margin and anatomical neck.

• Stability: Provided mainly by rotator cuff muscles (SITS).

• Bursae: Subscapular and subacromial (subdeltoid).

• Movements: Flexion, extension, abduction, adduction, rotation, circumduction.

• Axis: Multi-axial (three axes).

• Clinical:

  • Most common dislocation → anteroinferior.

  • Common lesion → rotator cuff tear (supraspinatus).

  • Axillary nerve injury → deltoid paralysis, sensory loss over “regimental badge”.

4. Elbow Joint

• Type: Complex hinge synovial joint (humeroulnar + humeroradial).

• Ligaments: Ulnar and radial collaterals, annular ligament of radius.

• Movements: Flexion (0–145°), extension (up to 0°).

• Carrying angle: 10–15° (males), 15–20° (females).

• Stability: Trochlear interlocking + strong collaterals.

• Clinical:

  • Pulled elbow (nursemaid’s elbow) → subluxation of radial head.

  • Supracondylar fracture → risk of brachial artery injury → Volkmann’s ischemia.

  • Olecranon bursitis → “student’s elbow”.

5. Radioulnar Joints

• Superior & inferior joints: Pivot synovial type.

• Middle joint: Fibrous (interosseous membrane).

• Movements: Supination and pronation around axis through head of radius and ulna.

• Supinators: Supinator, biceps brachii.

• Pronators: Pronator teres, pronator quadratus.

• Interosseous membrane: Fibres run downward and medially → transmit load from radius to ulna.

• Clinical: Monteggia (ulna fracture + radial head dislocation); Galeazzi (radius fracture + distal radioulnar dislocation).

6. Wrist (Radiocarpal) Joint

• Type: Ellipsoid (condyloid) synovial joint.

• Bones: Distal radius + articular disc with scaphoid, lunate, triquetral.

• Ligaments: Palmar, dorsal, ulnar, and radial collaterals.

• Movements:

  • Flexion (80°), Extension (70°), Abduction (20°), Adduction (45°), Circumduction.

• Clinical:

  • Colles’ fracture → dorsal displacement of radius (“dinner-fork deformity”).

  • Smith’s fracture → volar displacement (“garden-spade deformity”).

  • Scaphoid fracture → tenderness in snuffbox, risk of avascular necrosis.

7. Joints of Hand

a. Intercarpal & Midcarpal

• Plane synovial; small gliding movements; contribute to wrist flexibility.

b. Carpometacarpal (CMC)

• 2nd–5th: Plane synovial, limited movement.

• 1st (thumb): Saddle synovial, highly mobile — allows opposition.

• Clinical:

  • Osteoarthritis (1st CMC) common in women.

  • Gamekeeper’s (Skier’s) thumb → tear of ulnar collateral ligament.

c. Intermetacarpal

• Plane synovial; stabilize metacarpal bases.

8. Metacarpophalangeal (MCP) Joints

• Type: Condyloid synovial.

• Movements: Flexion, extension, abduction, adduction, circumduction.

• Collateral ligaments tighten during flexion → restrict abduction.

• Clinical:

  • Dislocation usually dorsal.

  • In rheumatoid arthritis → ulnar deviation.

9. Interphalangeal (IP) Joints

• Type: Hinge synovial.

• Movements: Flexion, extension only.

• Ligaments: Palmar plate + collaterals.

• Clinical:

  • Mallet finger → extensor rupture.

  • Boutonnière and Swan-neck deformities in rheumatoid arthritis.

  • Dupuytren’s contracture → palmar fascia fibrosis → flexion deformity.

  • Trigger finger → flexor sheath thickening.

10. Functional Notes

• Scapulohumeral rhythm: 2:1 ratio between glenohumeral and scapulothoracic movement during abduction.

• Shoulder mobility: Greatest range of any joint due to shallow socket and loose capsule.

• Elbow stability: Hinged trochlear system; limited side motion prevents injury.

• Interosseous membrane: Distributes load and stabilizes forearm rotation.

• Thumb opposition: Unique to humans → responsible for precision grip.

11. Clinical Correlations

✅ Summary Formula

Saddle → Plane → Ball → Hinge → Pivot → Ellipsoid → Saddle → Condyloid → Hinge
→ represents the progression of joint types from sternum to fingertips.