The supraspinatus, infraspinatus and teres minor tendons “…form a common tendinous cuff…” whose attachment to the humeral head, next to the bare area, can be seen through an arthroscope [Figure 16]. [1,6] This insertion site commonly appears fenestrated and is the region in which rotator cuff tears first occur. [6,7] The posterior cuff appears smooth and as aforementioned, the rotator cuff ridge can be seen arching “…across the posterior cuff to attach to the humeral head. 
From our study:
The rotator cuff ridge, a commonly overlooked and not well-described entity, was present in 34.1% of cases. Although not specifically documented, we did notice the appearance of the rotator cuff ridge to be variable. The number of ridges varied from 1-10, the ridges may be horizontal or vertical orientated and their depth may vary from shallow to prominent. No other study has commented on the prevalence or the appearance of the rotator cuff ridge.