Radius

Description

• Lateral bone of the forearm
• The head of the radius articulates proximally with the capitulum of the humerus.
• Neck of the of the radius is marked by the narrowing of the radius distal to the head.
• The radial tuberosity is located distally to the neck of the radius and proximally to the shaft.
  • It is a protrusion of the radius that serves as the distal attachment of the biceps brachii muscle.
• The shaft of the radius enlarges as it travels distally toward its articulation with scaphoid and and lunate carpal bones.
  • Medially, there is a concavity located at the distal end of the radius. It is known as the ulnar notch and allows for articulation with the head of the ulna, forming the distal radioulnar joint.
• The dorsal tubercle (Lister's tubercle) is the posterior projection at the distal end of the radius.
  • The extensor pollicus longus tendon wraps around this structure before extending the the phalanges of the 1st digit.
• The styloid process of the radius extends laterally at the distal end of the radius. It is larger than the styloid process of the ulna and extends more distally.
• Anular ligament
  • Extends from the surface of the ulna both anterior and posterior to the radial notch and wraps the head of the radius, holding it in the radial notch of the ulna. Helps to form the pivot type joint known as the proximal radio-ulnar joint.
    • The deep surface of the anular ligament is lined with a synovial membrane that continues as the sacciform recess of the proximal radio-ulnar joint, allowing rotation of the radial head within the ligament without damage to the synovial membrane.
• Radial Collateral ligament
  • Extends from the lateral epicondyle of the humerus and attaches onto the anular ligament of the radius with some fibers extending to the ulna.
• Interosseous membrane
  • A fibrous sheath of connective tissue that extends in an oblique course medially from the radius to the ulna. It holds the two bones together as well as separates the extensor and flexor compartments of the forearm.
  • Clinically, it allows the transmission of forces from the radius to the ulna and vice versa.

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Actions

• Articular
  • Articulates with Humerus to allow flexion and extension at the elbow.
  • Articulates with the Ulna to allow pronation and supination of the forearm.
  • Articulates with the Carpal Bones of the wrist to allow flexion and extension of the wrist.
• Muscle attachments
  • Biceps Brachii

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Vascular Supply

• Primarily Radial Artery
• Terminal branches of the Anterior Interosseous Artery, a branch of the Ulnar Artery

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Innervation

• Radial Nerve
• Median Nerve

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Clinical Significance

• Distal Radius Fracture
  • Barton's Fracture
  • Chauffer's Fracture
  • Colles' Fracture
  • Die-Punch Fracture
  • Radial Styloid Fracture
  • Smith's Fracture
• Other
  • Proximal Radius Fracture (Head, Neck)
  • Monteggia Fracture
  • Galeazzi Fracture
  • Essex Lopresti Fracture
  • Distal Radioulnar Joint Dislocation
  • Distal Radial Ulnar Joint Instability
  • Proximal Radioulnar Joint Instability
• Pediatric Considerations
  • Distal Radial Epiphysitis (Gymnast's Wrist)
  • Torus Fracture
  • Salter Harris Fracture
  • Plastic Deformation

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See Also

• Wrist Pain (Main)
• Hand and Wrist Anatomy (Main)
• Elbow Pain (Main)
• Elbow Anatomy (Main)

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