THE DELTOID MUSCLE ORIGIN - HISTOLOGIC CHARACTERISTICS AND EFFECTS OFSUBACROMIAL DECOMPRESSION

The histologic characteristics of the deltoid muscle attachment to nin e cadaveric acromia were studied using light microscopy. The deltoid m uscle attaches to the anterior and lateral acromion primarily by direc t tendinous attachment. The muscle attaches to the dorsal side of the acromion by periosteal fiber attachment. In the specimens studied, a h ypothetical acromioplasty of 4 mm would release, on average, 41% of th e direct fiber attachment, and a 6-mm acromioplasty would release 69% for all zones examined histologically. The functional and clinical eff ects of these findings are not known, but the deltoid muscle would be released by arthroscopic acromioplasty in areas where bone is removed.