RADIO-ULNAR JOINT

RADIO-ULNAR JOINT

1. What is the radio-ulnar joint It is a joint in the forearm that connects the radius bone to the ulna bone and allows rotation of the forearm.

2. Location Located between the distal end of the radius and the head of the ulna. It helps in movements like turning the palm up and down.

3. Types of radio-ulnar joints a. Proximal radio-ulnar joint b. Distal radio-ulnar joint c. Fibrous interosseous membrane between radius and ulna

4. Structure of radio-ulnar joint a. Radial head b. Ulnar notch on the distal radius c. Head of ulna d. Interosseous membrane e. Articular disc at distal radio-ulnar joint f. Annular ligament (at proximal joint) g. Accessory ligaments providing support

5. Functions of radio-ulnar joint a. Pronation of forearm b. Supination of forearm c. Helps in flexion and extension at elbow by stabilizing bones d. Maintains alignment between radius and ulna

6. Muscles acting on radio-ulnar joint a. Supinator – causes supination b. Biceps brachii – supination and flexion c. Pronator teres – pronation d. Pronator quadratus – pronation e. Brachioradialis – helps in rotation during flexion f. Extensor carpi radialis longus – assists rotation g. Anconeus – assists extension h. Triceps brachii – extension of forearm i. Brachialis – flexion of forearm

(Muscle sequence) 1 → Biceps brachii → flexion 2 → Brachialis → flexion 3 → Triceps brachii → extension 4 → Anconeus → extension 5 → Brachioradialis → rotation + flexion 6 → Extensor carpi radialis longus → rotation 7 → Supinator → rotation

7. Blood supply a. Radial artery b. Ulnar artery c. Interosseous branches supplying membrane and joint

8. Nerve supply a. Posterior interosseous nerve (C7-C8) b. Median nerve (C5-C7) c. Ulnar nerve (C8-T1)

9. Clinical importance a. Essential for pronation and supination b. Important in daily movements like writing, eating, lifting c. Injuries cause restricted rotation d. Interosseous membrane helps in force transmission from radius to ulna