Measurements on 319 macerated scapulae showed a size of the surface of the glenoid cavity between 3.5 and 9.7 cm2. We tried also to evaluate the size of this surface in living humans. This is principally possible, but in 10% of all scapulae there is an error range of more than +/- 1 cm2. The error range in small scapulae (greater than 5 cm2) can be reduced to +/- 0.58 cm2. The shoulder joint is not a ligament but a muscle dependent joint. Therefore the adhesion in this joint, relying on the smaller surface is very important. The small surface of cavitas glenoidalis in the context of habitual shoulder dislocation could be an important role.