I'm also completing my first year and we learned that the supraspinatus was active in EMG studies in the first 15 degrees of abduction/scaption. Also you have to consider that the deltoid is also the major participant. Yes this muscle helps to hold the humeral head in the glenoid fossa, as do all of the Wikipedia reference-linkrotator cuff muscles. Another hypothesis is that the supraspinatus is partly responsible for the decellerating of the shoulder, ie. when you are throwing a ball. Also, do you guys also learn to do the "full can" exercise vs. the "empty can" just curious, there's been research that impingement can occur with this muscle in the empty can position. GOod luck. Sandra