The gluteal muscles include the gluteus maximus, gluteus medius, gluteus minimus, and tensor fasciae latae. The posterior group includes the gluteus maximus, gluteus medius, and gluteus minimus. Two muscles called the gluteus medius and gluteus minimus stabilizes the upper leg. The lateral rotators also oppose medial rotation by the gluteus medius and gluteus minimus. The medius and minimus sit under the largest butt muscle, the gluteus maximus. Hip abduction is performed primarily by the hip abductors (gluteus medius and minimus). With the hip extended, the gluteus medius and gluteus minimus externally rotate the thigh. The nerve also courses between the gluteus medius and minimus. This gait is precipitated by strain to the gluteus maximus and gluteus minimus. The adductor minimus is an incompletely separated subdivision of the adductor magnus. The minimus has similar functions and both muscles are inserted onto the greater trochanter. The water opossum ("Chironectes minimus") of South America is the only opossum with interdigital webbing. The small blue ("Cupido minimus") is a Palearctic butterfly in the family Lycaenidae. The grey-cheeked thrush ("Catharus minimus") is a medium-sized thrush. It is smaller than "T. s. griseus" but larger than the least chipmunk ("Neotamias minimus").