Arrangement and innervation of the glutei medius and minimus and the piriformis: A morphological analysis

In order to examine the relationships between the positional arrangement and supplying nerves of the glutei medius and minimus and the piriformis, we investigated 49 pelvic halves of 28 cadavers. The superior gluteal nerve ran on the ventral surface of the piriformis in 44 cases (89.8%) (Type A), and some branches of the nerve perforated the piriformis in five cases (10.2%) (Type B). Based on the detailed findings of the innervation of the three muscles, the piriformis is chiefly composed of the caudal element of the gluteus medius (Type A) and in some cases the caudal element of the gluteus minimus as well (Type B).