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Radius and Ulna Bones Anatomy – Introduction

Introduction to the Radius and Ulna Bones Anatomy

  • The radius and ulna are the bones of the forearm. The forearm is the region of the upper limb that extends from the elbow to the wrist.
  • The image descriptionradius bone (os radius) supports the lateral (thumb) side of the forearm and the image descriptionulna bone (os ulna) supports the medial (little finger) side.
Radius and Ulna bones
Radius bone
Ulna bone
  • At the elbow, the radius and ulna articulate with the trochlea and capitulum of the image descriptionhumerus bone.
Elbow joint
Elbow joint labeled
  • The junction between the humerus and radius is a hinge joint, which permits flexion and extension movements (front to back) of the elbow.
  • At the wrist, the radius articulates with the proximal row of image descriptioncarpal bones to form an ellipsoidal joint.
Radius and Ulna bones
Carpal bones
  • This junction permits the wrist to move in two planes, flexion and extension (front to back) and abduction and adduction (side to side).
  • The forearm bones also image descriptionarticulate with each other. Proximally, the head of the radius forms a joint with the radial notch of the ulna, and distally, the head of the ulna forms a joint with the ulnar notch of the radius.
Before Radioulnar articulation 1
Before Radioulnar articulation 2
Radioulnar articulation
Radioulnar articulation labeled
  • These pivot joints allow the radius to rotate around the ulna, which turns the palm of the hand (pronation and supination).
  • An image descriptioninterosseous membrane spans the distance between the medial edge of the radius and the lateral edge of the ulna.
Interosseous membrane between the radius and ulna bones
Interosseous membrane between the radius and ulna bones labeled
  • This thin sheet of connective tissue separates the forearm into anterior and posterior compartments. It also transfers tension from the radius to the ulna and serves as an attachment point for some of the muscles that move the wrist and hand.

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Radius and Ulna Test yourself no-labels
Radius and Ulna Test yourself labeled