Anatomy Answer 3
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The articulation of the radius with the ulna is effected by ligaments which connect together the extremities as well as the bodies of these bones. The ligaments may, consequently, be subdivided into three sets:
1, those of the proximal radioulnar articulation;
2, the middle radioulnar ligaments;
3, those of the distal radioulnar articulation.
Proximal Radioulnar Articulation
- This articulation is a trochoid or pivot-joint between the circumference of the head of the radius and the ring formed by the radial notch of the ulna and the annular ligament.
The movements allowed in this articulation are limited to rotatory movements of the head of the radius within the ring formed by the annular ligament and the radial notch of the ulna; rotation forward being called pronation; rotation backward, supination.
- Supination is performed by the Biceps brachii and Supinator, assisted to a slight extent by the Extensor muscles of the thumb.
- Pronation is performed by the Pronator teres and Pronator quadratus.
- The shafts of the radius and ulna are connected by the Oblique Cord and the Interosseous Membrane.
- forms a non movable joint between these 2 bones called a syndesmosis.
- This is a pivot-joint formed between the head of the ulna and the ulnar notch on the lower end of the radius
- The movements in the distal radioulnar articulation consist of rotation of the lower end of the radius around an axis which passes through the center of the head of the ulna.
- When the radius rotates forward, pronation of the forearm and hand is the result; and when backward, supination
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Category: AIIMS Nov 2006 MCQs
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