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Posterior compartment of the thigh

  • HAMSTRING MUSCLES
    • Semimembranosus
    • Semitendinosus
    • Biceps femoris – long & short head

Semimembranosus

  • Origin
    • Ischial tuberosity – lateral part
  • Insertion
    • Medial condyle of tibia – horizontal cavity on the back
    • 3 expansions
      • forwards along medial surface of condlye deep to the tibial collateral ligament, separated from it by a bursa
      • obliquely upwards to lateral femoral condyle as the oblique popliteal ligament
      • strong fascia overlying popliteus & reaches the soleal line of the tibia
  • Nerve Supply
  • Action

Semitendinosus

  • Origin
    • Medial part of ischial tuberosity
    • On top of semimebranosus
  • Insertion
    • Tendon passes behind the medial condle & then curves forwardes to be inserted behind gracilis into the upper part of the subcutaneous surface of the tibia
  • Nerve Supply
  • Action

Biceps femoris

  • Sciatic nerve is beneath the long head
  • Origin
    • Long Head:
      • In common with semitendinosus
    • Short Head:
      • Whole length of linea aspera & upper part of lateral supracondylar line of femur
  • Insertion
    • Head of Fibula

Blood Supply of the Hamstrings

  • Upper
    • Inferior gluteal artery
  • Middle (main supply)
    • Profunda femoris artery & its perforating branches
  • Lower
    • Popliteal artery
  • These arteries form a series of anastomoses along the back of the thigh, the highest being the cruciate anastomosis

Nerve Supply

  • Tibial component of the sciatic nerve (L5S1)
    • Ischial part of adductor magnus
    • All three muscles
  • Common peroneal nerve
    • Short head of biceps

Action

  • Flexion of knee
  • Extension of hip
  • With knee semiflexed
    • biceps femoris is lateral rotator
    • semitendinosus/membranosus are medial rotators

Sciatic nerve

  • Passes through long head of biceps & adductor magnus
  • At popliteal fossa, a hands breath above knee joint it divides into tibial & common peroneal components
  • Surface Markings –
    • Midpoint between ischial tuberosity & greater trochanter to the apex of the popliteal fossa