GLUTEAL AND THIGH MUSCLES

• Gluteus medius (anterior part) and TFL

  • Internal rotators of the extended hip
  • Their leverage for Internal rotation increases when hip is flexed beyond 90 deg
• Piriformis

  • ER when hip is in extension
  • IR when hip in flexion
• Hip in a position of flexion as in climbing

  Adductors are forceful hip extensors
• Hip is extended


  Adductors are flexors
• Between 50-70 deg of hip flexion


  Adductors change from flexor to extensor action
• Gluteus Maximus

  • Upper portion- hip abductors
  • Lower portion- hip adductors
• Gluteus Medius

  • Anterior portion: IR
  • Posterior portion: ER
• Rectus Femoris


  • Can produce more force as hip flexor if the knees flexes simultaneously with the hip
  • Efficient as a knee extensor if the hip extends simultaneously with the knees
• Hamstrings


  • Efficient as hip extensors when the knee extends simultaneously with the hip
  • More efficient as knee flexors when the hip flexes simultaneously with the knees
• Muscles that produce hip flexion in standing

  • Rectus femoris
  • Iliopsoas
  • Sartorius
• Iliopsoas

  • Primary hip flexor regardless of hip positions
• Sartorius

  • Most important action is "simultaneous hip flexion and knee flexion" (when climbing in stairs)
• Hip flexion in the sitting position

  • Iliopsoas is the only muscle that can flex the hip beyond 90 deg
• Sit-ups and Straight leg raises (SLR)


  Abdominal muscles act synergistically with hip flexors
• Gluteus maximus


  Works as a force couple with the abdominal muscles to posteriorly tilt the pelvis on the femur, and flatten the lumbar spine, decreasing the lumbar lordosis
• Gluteus maximus

  • The most powerful hip extensor regardless of the knee position
• Hamstrings

  • Extend the hip when the knee is extended *optimal function at the hip joint
  • Hip extension with knee flexion= active insufficient position
• Prone-lying unilateral hip extension when knee extended

  Gluteus maximus increased activity as the hip extensor when in ER, and decreased activity as hip extensor when in IR, hamstrings is more efficient as the hip extensor if the hip is in hip IR
• Prone-lying unilateral hip extension with knee flexed

  Active-insufficiency of the hamstrings, hip extension with the knee flexed requires strong action of the gluteus maximus (the position is used to isolate the contraction of the gluteus maximus)
• Prone-lying bilateral hip extension, knee extended

  Lumbar extensors have increased activity
• Hip extensors in the sitting position

  Eccentric contraction of the hip extensors to permit forward movement to retrieve an object on the floor, and concentric contraction of the hip extensors produce return to erect position
• Functional motions of leaning forward in the sitting position, bending over to touch the toes in the standing position, climbing the stairs, or rising from a chair

  Hamstrings activated as hip extensors. "gluteus maximus" is also activated if this motions are rapid, or with moderate or maximum resistance
• Gluteus medius


  • Most powerful hip abductor (60%), 20 % from Gluteus minimus, 10% from TFL and Piriformis
• Hip abductors

  • Gluteus medius
  • Gluteus minimus
  • TFL
  • Upper fibers of the gluteus maximus
• UNILATERAL STANCE


  • The major function of the hip abductors is in closed-chain motion to maintain a level pelvis
• Adductors


  • Act as a hip IR
• Gluteus maximus


  • When extending the hip fully, also act as an ER
  • When the hip is flexed, the upper fibers act as an IR
• The 6 ERs of the hip

  Act as ER in hip extension, external rotary components of these muscles decrease in flexion of the hip, at 90 deg of hip flexion they possess a considerably abductor component
• Piriformis


  • Changes from an ER in hip extension to an IR in hip flexion
• Anterior portions of the gluteus medius, minimus and TFL

  Increased their leverage for IR when the hip is flexed - when the hip is flexed, the IR can produce almost 3 times they can produce when the hip is extended
• Hip flexion

  Increases IR leverage of the gluteus medius, minimus and piriformis