Ligament · Forearm

Interosseous membrane

Membrana interossea antebrachii

The broad fibrous sheet stretched between the facing borders of the radius and the ulna, filling most of the length of the gap between the two forearm bones. Its main fibres slope downward from the radius to the ulna, and that direction is the whole point: weight taken through the hand arrives at the radius and is passed across the sheet to the ulna, so the load reaching the elbow is shared rather than carried by one bone. It also walls the forearm into a front and a back compartment and gives the deep muscles of each an extra surface to arise from. Above its upper edge sits a gap through which the posterior interosseous vessels pass to the back of the forearm.