AnatomyUpper limbElbow and forearm

Radius and ulna: want to learn more about it?

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Radius and ulna

Learning objectives

After completing this study unit you will learn how to:

Name the major bony landmarks of the radius and ulna.
List the main ligaments that connect the radius with the ulna.

Watch a video

The radius and ulna are the two bones of the forearm. They articulate with the humerus at the elbow, and with the carpal bones at the wrist. In the anatomical position, the radius sits on the lateral aspect of the forearm, while the ulna is found medially. The radius and ulna articulate with each other at the proximal and distal radioulnar joints, while their bodies are connected by an interosseous membrane. These two joints allow the radius to move around the ulna, giving us the familiar palm facing up or palm facing down positions of the forearm. When the palm of the hand faces up (or forwards) we name this position supination. When the palm faces downwards the forearm is in a pronated position. Watch the following video and browse the atlas below to learn about the main features of these two bones.

Take a quiz

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Browse atlas

Radius and ulna: Like all long bones, the radius and ulna both have a head, a body or shaft, articulating surfaces and a number of ‘bumps and grooves’ that serve as attachment points for muscles and connective tissue, or pathways for nerves, vessels and tendons. The head of the radius is located at the bone’s proximal end. It is small and circular, and contributes to formation of the humeroradial joint (of the elbow) with the capitulum of the humerus. It also forms the proximal radioulnar joint with the radial notch of the ulna. The distal end of the radius is enlarged for articulation with both the ulna (distal radioulnar joint) and with the carpal bones at the wrist (radiocarpal joint). Unlike the radius, the head of the ulna is located at the bone’s distal aspect; it articulates with the radius at the distal radioulnar joint and does not participate in forming the wrist joint. The proximal end of the ulna, the olecranon, is shaped like a hook; this projection hinges around the trochlea at the distal end of the humerus forming the humeroulnar joint of the elbow. Browse the atlas to learn the specific features of the radial and ulna bones.

Summary

Key points about the radius and ulna
Bony landmarks of radius	Head, neck, articular circumference of head, articular facet of head, body, anterior border, posterior border, interosseous border, radial tuberosity, pronator tuberosity, suprastyloid crest, styloid process, dorsal radial tubercle, carpal articular surface
Bony landmarks of ulna	Olecranon, trochlear notch, coronoid process, tuberosity of ulna, radial notch, sublime tubercle, body, anterior border, posterior border, interosseous border, head
Ligaments	Interosseous membrane of forearm Oblique cord Annular ligament of radius Radial collateral ligament of elbow joint Ulnar collateral ligament of elbow Dorsal radioulnar ligament Palmar radioulnar ligament

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