Anatomy of the Forearm Bones: Radius and Ulna

Overview

• Bones Covered: Radius and Ulna
• Classification: Long bones
• Part of: Appendicular skeleton

Memory Tricks

• Ulna:
  • "Ulna is Under" - When shaking hands, the ulna is on the underside.
  • Olecranon Process: Bony part of the elbow, proximal end of the ulna.
• Radius:
  • "Radius Radiates" - In the anatomical position, the radius is on the lateral side.
  • Radial Pulse: Thumb is on the same side as the radius.

Interosseous Membrane

• Connects the radius and ulna.
• Consists of fibrous connective tissue with five ligaments.
• Provides support, strength, and muscle attachment points.

Detailed Anatomy

Ulna

• Olecranon Process:
  • Forms the elbow, proximal end.
  • Attachment for triceps brachii.
  • Fits into olecranon fossa of the humerus when forearm is extended.
• Coronoid Process:
  • Fits into coronoid fossa of the humerus during flexion.
  • Attachment for brachialis muscle.
• Trochlear Notch:
  • Between olecranon and coronoid processes.
  • Articulates with trochlea of the humerus; hinge joint.
• Radial Notch:
  • Depression accommodating the radius; forms proximal radioulnar joint.
  • Important Note: Radial notch is on ulna, ulnar notch is on radius.
• Head of the Ulna:
  • Located at the distal end; articulates with radius at ulnar notch.
  • Does not directly articulate with wrist bones.
• Styloid Process:
  • Small projection from the head of the ulna.
  • Attachment for ulnar collateral ligament of the wrist.

Radius

• Proximal End:
  • Rounded head; forms joint with capitulum of humerus.
  • Below the head is the neck, where radius narrows.
• Radial Tuberosity:
  • Rounded projection; attachment for biceps brachii.
• Styloid Process:
  • Distal end projection.
  • Attachment for muscles and radial collateral ligament.
• Ulnar Notch:
  • Depression accommodating the ulna's head; forms distal radioulnar joint.
  • Allows rotation of the forearm.

Additional Resources

• Free quiz available on the website.
• Anatomy playlist with additional bone videos.

Conclusion

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