Bony landmark · Shoulders

Spine of the scapula

Spina scapulae

The spine of the scapula is the sharp ridge running across the upper part of the back of the shoulder blade — easy to trace with a finger from beside the spine outwards to the tip of the shoulder. It divides the back of the blade into two hollows, the supraspinous fossa above and the infraspinous fossa below. The posterior fibres of the deltoid take origin along its lower border, and the trapezius inserts along its upper border, so the ridge is the seam where a shoulder muscle and a back muscle meet.