Bony landmark · Upper arm

Deltoid tuberosity

Tuberositas deltoidea

The deltoid tuberosity is a roughened, V-shaped patch about halfway down the outer side of the arm bone. The deltoid inserts here — all three of its heads, front, middle and back, converge from right across the shoulder onto this single small patch, which is how a muscle that caps the whole shoulder delivers its pull through one point on the shaft. The radial nerve runs in its own groove around the back of the bone just behind and below it.