Posterior Thigh and Popliteal Fossa Anatomy

Posterior Thigh and Popliteal Fossa

• The posterior thigh and popliteal fossa are anatomical regions in the human body.
• The femur is the longest, strongest, and largest bone in the body. Structures of the posterior thigh and popliteal fossa overlie the femur.
• Many structures of the posterior thigh and popliteal fossa arise in the gluteal area / pelvis.
• The posterior compartment of the thigh
  • Boundaries: Lateral intermuscular septum, adductor magnus, and deep fascia.
  • Contents: Hamstrings, nerves, and vascular structures.
• Common properties of the posterior compartment
  • Common action: Knee flexion, hip extension (mostly).
  • Common innervation: Sciatic nerve (tibial portion).
  • Common blood supply: Profunda femoris.
• Hamstrings
  • Semimembranosus
  • Semitendinosus
  • Biceps femoris (long head)
  • Biceps femoris (short head)
• Pes anserinus
  • Bursa on medial side of knee
  • Overlying bursa are tendons inserting to the medial side of the knee.
  • Muscle assortment for stabilizing medial knee and pelvis.
• Hip motion
  • Hip flexion is limited by hamstring flexibility.
  • Ability to flex hip > 70 degrees.
  • Adverse tension in sciatic nerve and tight hip ligaments restrict hip flexion
• Nerves
  • Sciatic nerve: Arises from sacral plexus (L4, L5, S1, S2, S3). It has two distinct portions.
    • Tibial
    • Common peroneal (fibular)
    • Variation in location where they split (usually mid-thigh)
    • Can be more proximal or distal.
    • All hamstrings are innervated by the tibial portion of the sciatic nerve, EXCEPT the short head of biceps femoris.
  • Posterior femoral cutaneous nerve: Arises from sacral plexus (S1 - S3).
• Vascular supply
  • Femur and hamstrings are supplied with blood by the profunda femoris artery.
  • Posterior compartment is drained by the profunda femoris vein, assisted by lymphatics.
• Popliteal fossa
  • Diamond-shaped space posterior to the knee.
  • Boundaries
    • Medial and lateral heads of gastrocnemius (plantaris)
    • Biceps femoris
    • Semimembranosus/tendinosus
  • Floor: posterior surface of femur, knee joint capsule, oblique popliteal ligament, and popliteus muscle.
  • Ceiling: embedded deep fascia, adipose tissue, part of posterior femoral cutaneous nerve, small saphenous vein.
  • Contents: Tibial nerve, popliteal artery, popliteal vein, common peroneal nerve, lymph vessels and nodes.

Popliteal Fossa - Significance

• Pulse palpable and dopplerable.
• May present with a popliteal cyst (Bakers cyst) in various knee pathologies or arthritis.
• LA injections can be done in this area.

Summary

• Students should now be able to identify the hamstrings, understand their functions, and identify major nerves and vascular structures in the posterior thigh/popliteal fossa. Students should also have a basic understanding of the clinical significance of the area.