Fig. 1

Normal skin from the anterior arm using a 50-MHz HFUS probe (Longport, Inc. EPISCAN). Note the fine hyperechoic epidermal entry echo. Deep to the entry echo is the hyperechoic dermis measuring about 1 millimeter (mm) with thicker horizontal bands in the deep dermis corresponding to the organized, horizontally arrayed collagen bundles in the reticular dermis. Deep to the dermis is the subcutis composed primarily of hypoechoic fat globules. Within this layer is the hyperechoic superficial fascia. Deep to the subcutis is the hyperechoic deep fascia overlying the biceps muscle