Gluteal Region Muscles

• The lecture covers muscles of the gluteal region.
• By the end of this lecture, students should be able to:
  • Define the gluteal region
  • Identify the sacrotuberous and sacrospinous ligaments
  • Describe the origin, insertion, nerve supply & action of the muscles of the gluteal region (tensor fascia lata, three glutei, six lateral rotators)
  • Define the role of the gluteal muscles in walking & the effect of their paralysis

Gluteal Region

• Located posteriorly to the pelvic girdle, at the upper end of the femur.
• The Sacrotuberous and sacrospinous ligaments stabilize the sacrum.
• The ligaments convert the greater and lesser sciatic notches into foramina.

Muscles of the Gluteal Region

• Muscles are split into two groups, superficial and six lateral rotators.
• Superficial muscles:
  • Gluteus maximus
  • Gluteus medius
  • Gluteus minimus
  • Tensor fascia lata

Tensor Fascia Lata

• Originates from the anterior part of iliac crest
• Inserts on the anterior border of ilio-tibial tract
• Receives nerve supply from superior gluteal nerve
• Tightens the ilio-tibial tract assisting in knee extension while standing and walking

Gluteus Maximus

• Originates from:
  • Outer gluteal surface of the ilium, behind the posterior gluteal line
  • Posterior surface of sacrum
  • Back of the sacro-tuberous ligament
• Insertion:
  • superficial ¾ - posterior border of ilio-tibial tract
  • deep ¼ - gluteal tuberosity
• Inferior gluteal nerve provides nerve supply
• Acts as the main thigh extensor at the hip joint, especially when rising from sitting, climbing, or running
• Involved in lateral rotation of the hip joint
• Tightens the ilio-tibial tract to assist in keeping the knee extended in standing.

Gluteus Medius

• Originates from the gluteal surface of the ilium,
  • Between the posterior and anterior gluteal lines
• Inserts on the lateral surface of the greater trochanter
• Nerve supply from the superior gluteal nerve
• Action:
  • Abduction of the thigh at the hip joint.
  • Medial rotation of the thigh at the hip joint.
  • Prevents tilting of the pelvis to the opposite side when the opposite leg is off the ground.

Gluteus Minimus

• Originates from the gluteal surface of the ilium,
  • Between the anterior and inferior gluteal lines
• Inserts on the anterior surface of the greater trochanter
• Nerve supply from the superior gluteal nerve
• Gluteus medius works with gluteus minimus

Paralysis of Gluteal Muscles

• Unilateral paralysis of both muscles causes a lurching gait.
• Bilateral paralysis causes a waddling gait.

Six Lateral Rotators

• The six muscles are:
  • Piriformis
  • Obturator internus
  • Superior gemellus
  • Inferior gemellus
  • Quadratus femoris
  • Obturator externus
• Common action is lateral rotation of the thigh at the hip joint.

Piriformis

• Originates from the front of the middle three sacral vertebrae
• Inserts on the tip of the greater trochanter

Obturator Internus

• Originates from:
  • Inner surface of obturator membrane
  • Margins of the obturator foramen
• Inserts on the medial surface of the greater trochanter

Superior Gemellus

• Originates from the upper margin of the lesser sciatic notch
• Inserts on the tendon of obturator internus

Inferior Gemellus

• Originates from the lower margin of the lesser sciatic notch
• Inserts on the tendon of obturator internus

Quadratus Femoris

• Originates from the lateral margin of the ischial tuberosity
• Nerve supply from the nerve to quadratus femoris
• Inserts on the quadrate tubercle

Obturator Externus

• Originates from:
  • Outer surface of obturator membrane
  • Margins of the obturator foramen
• Inserts on the trochanteric fossa of the femur.

Innervation of Lateral Rotators

• Piriformis receives branches from the sacral plexus (S1, 2)
• Obturator internus and the superior gemellus are innervated by the nerve to obturator internus
• Quadratus femoris and inferior gemellus are innervated by the nerve to quadratus femoris
• Obturator externus receives innervation from the obturator nerve.