Radius and Ulna Bones Anatomy

Author: Scott A. Sheffield MS

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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
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  • At the elbow, the radius and ulna articulate with the trochlea and capitulum of the image descriptionhumerus bone.
  • 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.

Learn the radius and ulna faster with these intelligent quizzes and free fill-in-the-blank diagrams.

Elbow joint
Elbow joint labeled
Carpal bones
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  • 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.
  • 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
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Anterior Markings of the Radius

  1. image descriptionRadial Head (caput radii) is a proximal, disc-shaped prominence. Its concave superior surface articulates with the capitulum of the humerus and its cylindrical lateral surface articulates with the radial notch of the ulna.
  2. image descriptionRadial tuberosity (tuberositas radii) is an oval elevation on the proximal, medioanterior margin of the radius. It is an attachment point for biceps brachii muscle.
  3. image descriptionRadial Neck (collum radii) is the region of bone between the head and tuberosity.
  4. image descriptionRadial Shaft or body (corpus radii) is the elongated region of bone that extends distal to the tuberosity.
  5. image descriptionInterosseous border of the radius (margo interosseus radii) is the medial edge (margin) of the bone where the interosseous membrane attaches. This thin connective tissue membrane divides the forearm into anterior and posterior compartments. It also is an attachment point for several forearm muscles and transfers tension from the radius to the ulna.
  6. image descriptionInterosseous border of the radius (margo interosseus radii) is the medial edge (margin) of the bone where the interosseous membrane attaches. This thin connective tissue membrane divides the forearm into anterior and posterior compartments. It also is an attachment point for several forearm muscles and transfers tension from the radius to the ulna.
  7. image descriptionUlnar notch (incisura ulnaris) is a mediodistal concavity that allows the radius to pivot around the head of the ulna during pronation and supination of the forearm, wrist, and hand.

Ulnar notch - Radius and Ulna Bones
Radial head - Radius and Ulna Bones
Radial tuberosity - Radius and Ulna Bones
Radial neck - Radius and Ulna Bones
Radial shaft - Radius and Ulna Bones
Interosseous border of Radius - Radius and Ulna Bones
Styloid process of Radius - Radius and Ulna Bones
Ulnar notch - Radius and Ulna Bones - labeled
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Anterior Markings of the Ulna

  1. image descriptionOlecranon or olecranon process (olecranon ulnae) is a large, fan-shaped superior projection from the proximal end of the ulna. Its curved anterior surface forms the superior portion of the trochlear notch (see below) and its rounded posterior surface forms the bump of the elbow. It also is an attachment site for the triceps brachii, anconeus, and flexor carpi ulnaris muslces.
  2. image descriptionCoronoid process (processus coronoideus) is a triangular-shaped, anterior projection from the proximal end of the shaft. It is an attachment site for the brachialis muscle.
  3. image descriptionTrochlear notch or semilunar notch (incisura trochlearis) is a deep depression at proximal end of the ulna formed by the curvatures of the olecranon and coronoid processes. This area articulates with the trochlea of the humerus at the elbow.
  4. image descriptionRadial notch (incisura radialis) is a depression along the lateral edge of the coronoid process that articulates with the head of the radius. The joint allows the radial head to rotate against the proximal end of the ulna during pronation and supination.
  5. image descriptionUlnar tuberosity (tuberositas ulnae) is a roughened eminence located just inferior to the anterior tip of the coronoid process. This area serves as the distal attachment (insertion) point for the brachialis muscle.
  6. image descriptionUlnar shaft (corpus ulnae) is the body of the bone that extends distal to the ulnar tuberosity.
  7. image descriptionInterosseous border of the ulna (margo interosseus ulnae) is the portion of the lateral margin of the bone where the interosseous membrane attaches.
  8. image descriptionUlnar head (caput ulnae) is a small rounded eminence at the distal end of the ulna. Its inferior surface articulates with the articular disc cartilage of the wrist, and its lateral surface articulates with the ulnar notch of the radius during pronation and supination of forearm, wrist, and hand.
  9. image descriptionStyloid process of the ulna (processeus styloideus ulnae) is a small projection that descends from the posterior portion of the ulnar head. It is an attachment point for the ulnar collateral ligament, which connects the ulna to the triquetral and pisiform carpal bones at the wrist.

Radius and Ulna Bones - Ulna
Olecranon process - Radius and Ulna Bones - Ulna
Coronoid process - Radius and Ulna Bones - Ulna
Trochlear notch - Radius and Ulna Bones - Ulna
Radial notch - Radius and Ulna Bones - labeled
Ulnar shaft - Radius and Ulna Bones
Interosseous border of Ulna - Radius and Ulna Bones
Ulnar head - Radius and Ulna Bones
Styloid process of Ulna - Radius and Ulna Bones
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Posterior Markings of the Radius

  1. image descriptionRadial Head (caput radii) is a proximal, disc-shaped prominence. Its concave superior surface articulates with the capitulum of the humerus and its cylindrical lateral surface articulates with the radial notch of the ulna.
  2. image descriptionRadial Neck (collum radii) is the region of bone between the head and tuberosity.
  3. image descriptionRadial Shaft or body (corpus radii) is the elongated region of bone that extends distal to the neck.
  4. image descriptionInterosseous border of the radius (margo interosseus radii) is the medial edge (margin) of the bone where the interosseous membrane attaches.  This thin connective tissue membrane divides the forearm into anterior and posterior compartments. It also is an attachment site for several forearm muscles and transfers tension from the radius to the ulna.
  5. image descriptionStyloid process of the radius (processus styloideus radii) is a thick, pointed, lateral projection from the distal end of bone. It forms the lateral portion of the wrist joint and serves as an attachment site for the brachioradialis muscle and radial (lateral) collateral ligament

Use these interactive radius and ulna quizzes to learn this topic efficiently, and from scratch!

Radius and Ulna Bones - Posterior View
Radial head - Radius and Ulna Bones - Posterior View
Radial neck - Radius and Ulna Bones - Posterior View
Radial shaft - Radius and Ulna Bones - Posterior View
Interosseous border of radius - Radius and Ulna Bones - Posterior View
Styloid process of radius - Radius and Ulna Bones - Posterior View
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Posterior Markings of the Ulna:

  1. image descriptionOlecranon or olecranon process (olecranon ulnae) is a large, fan-shaped superior projection from the proximal end of the ulna. Its curved anterior surface forms the superior portion of the trochlear notch, and its rounded posterior surface forms the bump of the elbow. It also is an attachment site for the triceps brachii, anconeus, and flexor carpi ulnaris muslces.
  2. image descriptionUlnar shaft (corpus ulnae) is the body of the bone that extends distal to the olecranon.
  3. image descriptionInterosseous border of the ulna (margo interosseus ulnae) is the portion of the lateral margin of the bone where the interosseous membrane attaches.
  4. image descriptionUlnar head (caput ulnae) is a small rounded eminence at the distal end of the ulna. Its inferior surface articulates with the articular disc cartilage of the wrist, and its lateral surface articulates with the ulnar notch of the radius during pronation and supination of forearm, wrist, and hand.
  5. image descriptionStyloid process of the ulna (processeus styloideus ulnae) is a small projection that descends from the posterior portion of the ulnar head. It is an attachment point for the ulnar collateral ligament, which connects the ulna to the triquetral and pisiform carpal bones at the wrist.
Radius and Ulna Bones - Posterior View
Olecranon - Radius and Ulna Bones - Posterior View
Ulnar shaft - Radius and Ulna Bones - Posterior View
Interosseous border of ulna - Radius and Ulna Bones - Posterior View
Ulnar head - Radius and Ulna Bones - Posterior View
Styloid process of ulna - Radius and Ulna Bones - Posterior View
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Test yourself:

  1. Overview: [image descriptionShow/image descriptionHide]
  2. Radius (anterior): [image descriptionShow/image descriptionHide]
  3. Ulna (anterior): [image descriptionShow/image descriptionHide]
  4. Ulna (posterior): [image descriptionShow/image descriptionHide]
  5. Radius (posterior): [image descriptionShow/image descriptionHide]
Radius and Ulna Test yourself no-labels
Radius and Ulna Test yourself labeled
Radius and Ulna Bones - Test youreself - Part1
Radius and Ulna Bones - Test youreself - Part1 - Answers
Radius and Ulna Bones - Test youreself - Part2
Radius and Ulna Bones - Test youreself - Part2 - Answers
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Interactive quizzes about the radius and the ulna

Radius and Ulna Bones Quiz: Anterior Markings

Radius and Ulna Bones Quiz: Posterior Markings

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