Lab 6 - Module 1 - The Gluteal Region: Page 3 of 8

Muscles of the Gluteal Region

Add the Obturator Internus muscle.

Origin - Arises as a large fan-shaped muscle from the; pelvic margins of the obturator foramen, from the medial two-thirds of the obturator membrane that fills it and from the antero-lateral pelvic surface of the ilium.

Insertion - Trochanteric fossa of the femur

Innervation - Nerve to Obturator Internus (L5, S1)

Action - External rotation of the femur; abduct the flexed thigh

Rotate the pelvis for a posterior view. Follow the tendon of Obturator Internus as it attaches to the trochanteric fossa of the femur.

Add the Superior Gemellus muscle.

Origin - Gluteal surface of the ischial spine.

Insertion - Trochanteric fossa of the femur

Innervation - Nerve to Obturator Internus (L5, S1)

Action - Laterally rotates the extended hip joint and abducts the flexed hip joint.

Add the Inferior Gemellus muscle. Arise from the superior and inferior margins of the lesser sciatic notch on either side of the obturator internus tendon. The inferior gemellus muscle is the larger of the two gemelli.

Origin - The proximal part of the ischial tuberosity

Insertion - Trochanteric fossa of the femur

Innervation - Nerve to Quadratus Femoris

Action - Laterally rotates the extended hip joint and abducts the flexed hip joint

Add the Quadratus Femoris muscle which lies posterior to the hip joint and femoral neck, separated from them by the tendon of obturator externus and the transverse branch of the medial circumflex femoral artery. There is often a bursa between the anterior aspect of the muscle and the lesser trochanter.

Origin - Superior lateral margin of the ischial tuberosity

Insertion - Quadrate tubercle on the intertrochanteric crest of the femur

Innervation - Nerve to Quadratus Femoris

Action - External rotation of the thigh

Add the Piriformis muscle. The anterior surface of the piriformis is related to the rectum, the sacral plexus and branches of the internal iliac vessels. Outside the pelvis, the anterior surface is in contact with the posterior surface of the ischium and the capsular hip joint. Sciatic, posterior femoral cutaneous and pudendal nerves, inferior gluteal and internal pudendal vessels and muscular branches from the sacral plexus, lie in the interval between piriformis and the superior gemellus/obturator internus.

If the common fibular (peroneal) nerve leaves the pelvis separately, it may pierce the piriformis muscle, whose anterior surface is intimately related to the sacral plexus.

Origin - Anterior surface of the sacrum; sacrotuberous ligament

Insertion - Superior border of the greater trochanter of the femur

Innervation - Branches of the ventral rami of S1, S2 (AKA Nerve to Piriformis)

Action - External rotation of the femur; abduct the flexed thigh