The muscles can be divided into four major groups: 1. Muscles of the pelvico-femural group. 2.Muscles of the femur. 3: Muscles of the knee joint. 4: Muscles of the foot. Special muscles to the pelvic girdle are not considered, since the pelvic girdle is rigid. The muscles of the lower limbs have the nerve supply through the lumbar and sacral plexuses.
Muscles of the pelvico-femural group:
These muscles take origin from the pelvic girdle and anchor the femur, so as to perform motion to the hip joint to all possible rotations. These muscles are divided into anterior, posterior and medial groups.
The anterior group: Flexing the hip joint, they are attached to the lesser trochanter. Iliopsoas ( psoas major, m.iliacus and minor psoas)
1. Iliopsoas muscle has two heads , psoas major originating from the lateral walls of bodies and intervertebral structures of the 12th dorsal vertebral body, down to the 4th lumbar body, including the transverse processes of these bodies. The muscle fibers continue down and in slight lateral direction, becoming united with iliac muscle, which take origin from the iliac fossa, and the anterior and inferior iliac spines In the groove between the tow heads running the femoral nerve. The iliopsoas muscle running anterior to the hip joint , passing the lacuna musculorum of the inguinal canal. The muscle including flexing the hip joint , can flex the pelvis and the trunk anteriorly , in case of keeping the legs fixed. The innervation is from L2-4 roots through the lumbar plexus.
2. Psoas minor: Not in all people can be seen, it is laying above the iliopsoas muscle, transforming to iliac fascia , anchoring to the iliopubic eminence. It stretches the iliac fascia and flex the lumbar spine. The innervation is from L1-2 roots through the lumbar plexus.
The posterior group: Extensors, rotators and adductors of the hip joint, they are attached to the greater trochanter and its surrounding area. In this group the following muscles: m.gluteus maximus, m.gluteus medius, m.tensor fasciae latae, m. gluteus minimus, m. piriformis, m. obturatorius, mm. gemelli, m. quadratus femoris and m. obturatorius externus.
1. Gluteus maximus: A massive muscle taking origin from the outer surface of the iliac bones , the thoraco-lumbar fascia , lateral aspects of the sacrum and coccygeum and sacrotuberal ligament, going down. The anterior part of the muscle transforming to wide ligament, running around the lateral aspect of the major trochanter continue in the form of iliotibial tact. The posterior part of the muscle anchor to the gluteal tuber of the femur. In addition to hip extension, it rotate the hip laterally. With tension it keep pelvic and trunk balance. The innervation is from L5-S1 roots through the sacral plexus.
2: Gluteus medius: Originate from the outer layer of the iliac bone with point of fixation to the lateral surface of the greater trochanter, near its tip. During contraction it abduct the hip. The anterior part of the muscle, when contracting in isolation, rotate the femur inside, but the posterior part , rotate outside. In standing position, during its contraction, it bends the pelvis to its side. The innervation is from L4-S1 roots through the sacral plexus.
3:Tensor fasciae latae: Anterior to the gluteus medius at the lateral surface of the thigh, between two sheets, which unify to form the iliotibial tact, which anchor to the lateral epicondyle of the tibial bone. During contraction, it flexes the hip and knee joints and outer rotation of the last. The innervation is from L4-S1 roots through the sacral plexus.
4:Gluteus minimus: Below the gluteus medius, originate from the outer surface of the iliac bone to be attached to the anterior aspect of the greater trochanter. Functioning the same as gluteus medius. The innervation is from L4-S1 roots through the sacral plexus.
5.Piriform muscle: Originate from the pelvic side of the sacrum, lateral to the sacral foramen. It cross the major ischiadic foramen from the pelvic cavity horizontally , posterior to the hip joint to be attached to the greater trochanter. It rotate the femur outside and to lesser degree abducting it. With legs fixed, it rotate the pelvis to its side and anteriorly. The innervation is from S1-2 roots through the sacral plexus.
6.Internal obturator muscle: originate from the boundaries of the obturator foramen and membrane, encircling the minor ischiadic foramen, to be attached to the trochanteric fossa of the femur. Parallel to the ligament of the internal obturator muscle after emergence from the pelvic cavity, the two gemelli muscles also attach the fossa trochanterica . These muscles rotate the femur outside. The innervation is from L4-S2 roots through the sacral plexus.
The medial group: Adducting the hip joint, except gracilis muscle, which is attached to the tibia, they are attached to linea aspera femoris. In this group the following muscles: M. pectineus, m. adductor longus , m. adductor brevis, m. adductor magnus and gracilis muscle.