Lumbar Spine, Hip and Knee - LO 2
2. Describe the muscles of the gluteal/hip region, and discuss the function of each with particular attention to the role in locomotion. Consider the effect a lesion would have on the nerves and the muscular compartments they serve.
The muscles of the gluteal and hip region primarily take origin from the posterior surface of the ilium (iliac blade) and posterior portion of the ischium. They all cross the hip and insert onto the proximal femur, and act on the hip joint.
*Students are only responsible for muscles discussed in the main text of the learning objectives and/or list of structures
There are 3 gluteal muscles:
The gluteal muscles are arranged in three layers all taking origin from the posterior surface of the iliac blade. The gluteus maximus m. is most superficial, has the largest surface area, and overlies all of the muscles of the gluteal and hip region. Deep to the superior portion of the gluteus maximus is the gluteus medius m., and deep to the medius is the gluteus minimus m. lying directly on the posterior surface of the ilium.
The gluteus maximus m. is a powerful extender of the hip joint and the gluteus medius and minimus mm. are abductors of the thigh at the hip joint. All are involved in locomotion: maximus especially for climbing stairs or inclines and for rising from a sitting or squatting position; medius and minimus function to keep the pelvis from dropping on the unsupported side when only one leg is supporting the body – the abductors contract on one side to keep the pelvis from falling or dropping on the other side when the leg is not supporting it; eg during the normal walking cycle.
Deep muscles:
Deep to the gluteus maximus m., and inferior to the gluteus medius and minimus mm. is the piriformis m. It originates inside the pelvic cavity, taking origin from the anterior surface of the sacrum. It exits through the greater sciatic foramen of the pelvis (having a very close relationship to the sciatic n.) and inserts on the greater trochanter of the femur.
Inferior to the piriformis mm. are several hip rotators: obturator internus, superior and inferior gemelli mm., and quadratus femoris m. These muscles take origin from the ischium, insert onto the proximal femur, and laterally rotate the hip.
