Muscles of the Posterior Thigh

Muscles of the Posterior Thigh (and other important landmarks) Gluteus medius Gluteus maximus Gracilis Adductor magnus (Iliotibial tract) Semitendinosus Semimembranosus Biceps femoris: Long head Short head Muscles Crossing Hip and Knee Joints Muscles of the Posterior Compartment of Pelvis 1) Gluteus maximus a. Actions: extends thigh (at hip) for climbing stairs and running, laterally rotates thigh (opposite action of the iliopsoas muscle). b. Innervation: Inferior gluteal nerve c. Origin: from ilium and dorsal sacrum Deep muscles of gluteal region (Gluteus maximus d. Insertion: to gluteal tuberosity of femur and iliotibial tract and medius cut for view) 2) Gluteus medius a. Actions: abducts and medially rotates thigh for walking, holds up pelvis when waling so it doesn’t tip down and foot can swing free of the ground b. Innervation: Superior gluteal nerve 4 (deep) c. Origin: from ilium 5 d. Insertion: to greater trochanter 7 6 of femur 2 3 8 1 3) Gluteus minimus a. Actions: aids Gluteus medius in actions b. Innervation: Superior gluteal nerve c. Origin: from ilium d. Insertion: to greater trochanter of femur Gracilis Adductor magnus 2 11 1 11 10 9 Muscles Crossing Hip and Knee Joints Lateral Rotators of Thigh (Posterior) 4) Piriformis a. Actions: lateral rotator of thigh, aids in abduction of thigh when hip is flexed b. Innervation: S1, S2, L5 c. Origin: from anterior sacrum d. Insertion: to greater trochanter of femur 5) Obturator externus a. Actions: lateral rotator of thigh, stabilizes hip joint b. Innervation: Obturator nerve c. Origin: from margin of obturator foramen on pubis and ischium d. Insertion: to posterior femur between greater and lesser trochanter of femur 6) Obturator internus a. Actions: lateral rotator of thigh, stabilizes hip joint b. Innervation: L5 – S1 c. Origin: from obturator membrane and greater sciatic notch d. Insertion: to greater trochanter of femur 7) Gemellus (Superior and Inferior) a. Actions: lateral rotator of thigh, stabilizes hip joint b. Innervation: L4, L5, S1 c. Origin: from ischial tuberosity d. Insertion: to greater trochanter of femur 8) Quadratus femoris a. Actions: lateral rotator of thigh, stabilizes hip joint b. Innervation: L4, L5, S1 c. Origin: from ischial tuberosity d. Insertion: to greater trochanter of femur Deep muscles of gluteal region (Gluteus maximus and medius cut for view) 2 3 4 6 (deep) 5 7 8 1 Gracilis Adductor magnus 2 11 1 11 10 9 Muscles Crossing Hip and Knee Joints Muscles of the Posterior Compartment of Thigh (Knee Flexors and Thigh Extensors) Hamstrings – three-muscle complex 9) Biceps femoris a. Actions: extends thigh at hip, flexes knee, laterally rotates leg b. Innervation: Sciatic nerve c. Origin: long head from ischial tuberosity, short head from linea aspera d. Insertion: to lateral leg to fibula head and lateral condyle of tibia Deep muscles of gluteal region (Gluteus maximus and medius cut for view) 10) Semitendinosus a. Actions: extends thigh at hip, flexes knee, medially rotates leg b. Innervation: Sciatic nerve c. Origin: from ischial tuberosity d. Insertion: to medial tibial shaft 2 3 4 11) Semimembranosus a. Actions: extends thigh at hip, flexes knee, medially rotates leg b. Innervation: Sciatic nerve c. Origin: from ischial tuberosity d. Insertion: to medial condyle of tibia 6 (deep) 5 7 8 1 Gracilis Adductor magnus 2 11 1 11 10 9