Elbow Joint

Description

Lateral illustration of the elbow joint showing the joint space, synovium, capsule and posterior fat pad

Bony anatomy of the elbow

Lateral elbow radiograph labeled

General

• Synovial hinge joint between the humerus, the radius, and the ulna.
• Responsible for elbow flexion/extension and contributes to forearm pronation/supination

Ligaments

• Ulnar Collateral Ligament medially.
• Lateral Collateral Ligament Complex of the Elbow laterally.
• Quadrate ligament (of Denuce)
  • Thickening of the inferior aspect of the joint capsule
  • Runs from just inferior to the radial notch of the ulna to insert to the medial surface of the radial neck
• Oblique Cord
  • Inconstant thickening of supinator muscle fascia and functionally insignificant
  • Runs from tuberosity of the ulna to just distal to radial tuberosity

Articulations/ Joints

• Radiohumeral or Radiocapitellar: Between the radial head and capitellum of the humerus.
• Ulnohumeral: Between the trochlear notch of the ulna and trochlea of the humerus.
• Proximal Radioulnar Joint: between the radial head and the radial notch of the ulna.

Joint Capsule

• The joint capsule has two layers, deep and superficial.
• The joint capsule attaches to the radial, coronoid and olecranon fossae proximally.
• The joint capsule attaches annular ligament of the radius and coronoid process of the ulna distally.
• Volume is 24-30 mL
• There are several synovial folds

Fat Pads

• There are three fat pads of the elbow:
  • Coronoid fossa
  • Radial fossa
  • Olecranon fossa
• Displacement of the fat pads, producing the posterior fat pad sign, is a radiographic feature of an elbow joint effusion

Bursae

• Olecranon Bursa
  • Superficial: lies between the olecranon and the subcutaneous tissue
  • Subtendinous: lies between olecranon and triceps brachii tendon
  • Intratendinous: variably lies in the triceps brachii tendon
• Bicipitoradial bursa

Variant Anatomy

• Synovial folds
  • Thin projections of synovial membrane on the inner layer of joint capsule
  • May be confused with intra-articular loose bodies on MRI
• Capitellar and olecranon pseudo-defects
  • Normal areas devoid of articular cartilage
  • can be mistaken on MRI for impaction injuries or osteochondral defects
• Accessory Ossicles
  • Os supratrochlear dorsale
  • Patella cubiti (very rare)

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Actions

Hinge

• Allows flexion-extension and is formed by the ulnohumeral articulation
• Primary flexors: biceps brachii, brachialis, brachioradialis
• Secondary flexors: pronator teres, palmaris longus, flexor digitorum superficialis, extensor carpi radialis longus, extensor carpi radialis brevis
• Extensors: triceps brachii

Pivot

• Allows pronation-supination is formed by the radiohumeral articulation, proximal radioulnar joint
• Primary pronators: pronator teres, pronator quadratus
• Secondary pronators: brachioradialis
• Supinators: supinator, biceps brachii

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Vascular Supply

• Branches of the radial, ulnar and brachial arteries.

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Innervation

• Radial Nerve
• Ulnar Nerve
• Median Nerve
• Musculocutaneous Nerve

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Clinical Significance

• See: Elbow Pain Main

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See Also

• Elbow Pain Main
• Elbow Anatomy Main

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