The structure indicated is the suprascapular notch.
The suprascapular notch is a notch in the superior border of the scapula, and lies medial to the base of the coracoid process.
The superior transverse scapular ligament runs across the top of the notch, converting it into an opening, or foramen.
Below this ligament, the suprascapular nerve passes through.
Above this ligament, the transverse scapular vessels pass.