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Leg - Posterior
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Leg - Posterior

Primary actions of the posterior compartment muscles are:
  • Foot plantar flexion.
  • Leg flexion
Posterior knee:
Popliteus:
  • Originates on the lateral femoral condyle and the popliteal ligament
  • Inserts on the proximal tibia;
  • It flexes and medially rotates the leg,
Superficial leg (from deep to superficial):
Soleus:
  • Originates on proximal head of the fibula and the soleal line of the tibia
  • Inserts on the calcaneus via calcaneal tendon
  • Plantar flexes the foot.
Gastrocnemius:
  • Originates on lateral and medial femoral condyles
  • Inserts on calcaneus via calcaneal tendon
  • Plantar flexes the foot and flexes the knee.
  • Gastrocnemius joins soleus to form the calcaneal tendon (aka the "Achilles' tendon," aka the "triceps surae") where they insert on the calcaneus.
Deep leg (from lateral to medial):
Flexor hallucis longus:
  • Originates on the distal 2/3rds of the fibula and interosseous membrane
  • Inserts on the base of the distal phalanx of digit 1
  • It plantar flexes the foot and flexes the distal phalanx of digit 1.
Tibialis posterior
  • Originates on the proximal tibia, fibula, and interosseous membrane
  • Inserts primarily at the navicular tuberosity and medial cuneiform
  • It plantar flexes and inverts the foot.
  • Tibialis posterior is the deepest muscle of the posterior compartment; it lies directly against the posterior tibia.
Flexor digitorum longus:
  • Originates on the middle tibial shaft
  • Inserts on the distal phalanges of digits 2-5
  • It flexes the corresponding toes and plantar flexes the foot.
Primary actions of the posterior compartment muscles are:
  • Foot plantar flexion.
  • Leg flexion
  • The tendons of the deep muscles of the posterior lower leg cross at the ankle.
From lateral to medial superior to the ankle, their order is: – Flexor hallucis longus – Tibialis posterior – Flexor digitorum longus A mnemonic to remember this order is: Have a Terrific Day (Have = Hallucis; Terrific = Tibialis; Day = Digitorum)
  • From medial to lateral at the ankle, their order is:
– Tibialis posterior – Flexor digitorum longus – Flexor hallucis longus A mnemonic to remember this order is: Tom, Dick, and Harry (Tom = Tibialis; Dick = Digitorum; Harry = Hallucis).

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