Corpus3D

Elbow

Posterior border of the ulna

Margo posterior ulnae

How to find it
From the olecranon a sharp ridge runs along the whole back of the forearm to the ulnar styloid. It lies subcutaneously and can be traced along its full length.
What you use it for
The divide between the flexor and extensor compartments of the forearm, and the reference for judging the position of radius and ulna in a fracture.
On the bone
Ulna
Body region
Elbow