5.2 Lower Limb Exam : Deep Gluteal Muscles (Pelvitrochanteric Group & Cranial-to-Caudal Order)

Deep gluteal muscles - Cranial to Caudal Order

Gluteus minimus -> Piriformis -> Superior gemellus -> Obturator internus -> Inferior gemellus -> Obturator externus -> Quadratus femoris

Gluteus minimus - Origin and Insertion

Origin: External surface of ilium between anterior and inferior gluteal lines. Insertion: Anterior and anterolateral aspect of greater trochanter of femur

Gluteus minimus - Actions

Abduction and medial (internal) rotation of the hip; stabilizes pelvis during single-leg stance by assisting gluteus medius

Gluteus minimus - Specificity and Layer

Most cranial muscle of the deep gluteal layer; functionally acts as an internal rotator and abductor unlike the external rotators situated below it

Piriformis - Origin and Insertion

Origin: Anterior surface of sacrum (between anterior sacral foramina S2-S4) and sacrotuberous ligament. Insertion: Superior border and medial part of greater trochanter of femur

Piriformis - Actions

Lateral (external) rotation of extended hip; Internal rotation of the flexed hip; abduction of flexed hip; stabilizes femoral head within acetabulum

Piriformis - Specificity and Landmark

Traverses greater sciatic foramen, dividing it into suprapiriform and infrapiriform spaces (crucial landmark for gluteal vessels and sciatic nerve)

Superior gemellus - Origin and Insertion

Origin: External surface of ischial spine. Insertion: Blends with tendon of obturator internus onto medial aspect of greater trochanter of femur

Superior gemellus - Actions

Lateral (external) rotation of extended hip; abduction of flexed hip; stabilizes femoral head within acetabulum

Superior gemellus - Specificity and Topography

Located directly superior to obturator internus tendon; originates from ischial spine above lesser sciatic notch

Obturator internus - Origin and Insertion

Origin: Pelvic surface of obturator membrane and surrounding margins of obturator foramen. Insertion: Medial aspect of greater trochanter of femur (joined by gemelli tendons)

Obturator internus - Actions

Lateral (external) rotation of extended hip; abduction of flexed hip; stabilizes femoral head within acetabulum

Obturator internus - Specificity and Trajectory

Originates inside true pelvis, turns acutely at 90 degrees around lesser sciatic notch to exit pelvis toward greater trochanter

Inferior gemellus - Origin and Insertion

Origin: Superior surface of ischial tuberosity. Insertion: Blends with tendon of obturator internus onto medial aspect of greater trochanter of femur

Inferior gemellus - Actions

Lateral (external) rotation of extended hip; abduction of flexed hip; stabilizes femoral head within acetabulum

Inferior gemellus - Specificity and Topography

Located directly inferior to obturator internus tendon; originates from upper part of ischial tuberosity below lesser sciatic notch

Obturator externus - Origin and Insertion

Origin: External surface of obturator membrane and adjacent margins of obturator foramen. Insertion: Trochanteric fossa of femur

Obturator externus - Actions

Lateral (external) rotation of thigh at hip joint; stabilizes hip joint

Obturator externus - Specificity and Plane

Does not lie in the same dorsal plane as other deep gluteal muscles; inserts specifically into trochanteric fossa rather than greater trochanter proper

Quadratus femoris - Origin and Insertion

Origin: Lateral surface of ischium immediately anterior to ischial tuberosity. Insertion: Quadrate tubercle of intertrochanteric crest of femur

Quadratus femoris - Actions

Powerful lateral (external) rotation of thigh at hip joint; assists in hip adduction

Quadratus femoris - Specificity and Landmark

Most caudal muscle of deep gluteal group; directly marks its bony insertion via the quadrate tubercle on posterior femur