JointUpper limb

Proximal radioulnar joint

articulatio radioulnaris proximalis

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Study entry

Classification

Pivot (trochoid) synovial joint.

Surfaces

Head of the radius with the radial notch of the ulna.

Capsule

Capsule continuous with that of the elbow. The annular ligament of the radius, attached to the ulna in front of and behind the radial notch, forms with it a ring around the head of the radius.

Movements

Pronation and supination: the head of the radius rotates within the ring. Supination by the supinator (without resistance) and by the biceps (against force); pronation mainly by the pronator quadratus and, secondarily, by the pronator teres.

Blood supply

Radial part of the elbow arterial network: radial and middle collaterals, anastomosed with the radial and interosseous recurrents.

Innervation

Mainly musculocutaneous, median and radial.

Clinical

Pronation depends above all on the median nerve; supination, on the musculocutaneous and the radial.

Source: cap. 3, «Articulaciones del miembro superior: articulación radioulnar proximal»

Clinical correlation

Subluxation of the radial head ("nursemaid's elbow")

In preschoolers, above all girls, suddenly pulling the child by the arm with the forearm pronated (swinging in the air, for example) makes the head of the radius slip partly out of the annular ligament. The child cries and does not use the arm, which is held with the elbow flexed and the forearm pronated. The pull tears the distal attachment of the annular ligament at the neck of the radius; the head descends and comes partly out of the ligament's "cup", and the torn piece may be caught between the head of the radius and the capitulum of the humerus; this pinching is what hurts. It is treated by supinating the forearm with the elbow flexed; the ligament heals with a sling for 2 weeks.

Related clinical cases

Subluxation of the radial head ("nursemaid's elbow")