Anatomy: Is there a reason why the Teres Major is not part of the Rotator cuff muscle grouping? Is there a name of the plane if you are moving at a 45 degree angle?

Kinesiologists have decided which muscles make up the rotator cuff; it is a standard anatomy/physiology classification. We have no idea why they didn't include Teres Major, but its position may be part of the reason, as it is more inferior/distal and does not really act like a cuff on the shoulder, like the others. We teach the cardinal planes in the course as these are the most commonly used but anything that's not in a cardinal plane could be thought of as being in the oblique plane. Google this along with "scaption" and you'll learn about two more planes :) If we understand your question, this is our answer. From downward dog, any movement of your leg toward anatomical neutral *is* extension. If we've said otherwise in the materials, please let us know where. Finally, the muscles attached to the fibula (or perone) are alternately called peroneal and fibularis muscles. We think one is Greek and the other Latin. Anatomical parts - for better or worse - frequently have more than one name.