Fig. 4

40 year old specimen. A Ultrasonographic view with linear transducer 12 MHz in human volunteer of the origin of LM at the dorsal sacrum, level S3 (inset shows position of probe). Arrows indicate the dorsal surface of the sacrum; GM = gluteus maximus. LM 3–5 refer to the separate bands of LM. B Transversal cross-section at level S3 with similar orientation as Fig. A, showing the three most caudal bands of LM medial and deep to gluteus maximus (GM); each band is demarcated in separate colors; red represents band 3, yellow represents band 4 and blue band 5. SI-J = sacro-iliac joint. I and II refer to the median and lateral sacral crest, respectively. White arrowheads (Figs A, B) indicate the erector spinae aponeurosis