Thigh and Popliteal Fossa

Thigh Muscles - Compartment Crew

Muscles of the thigh are organized into three main compartments:

• Key Points:
  • 📌 Pes Anserinus ("Say Grace Before Tea"): Common tendinous insertion of Sartorius, Gracilis, semiTendinosus on anteromedial tibia.
  • Pectineus: Medial compartment muscle, often has dual innervation: Femoral N. and Obturator N.
  • Adductor Magnus:

    ⭐ Adductor magnus has dual innervation: Obturator N. (adductor part) & Tibial div. of Sciatic N. (hamstring part).

Femoral Triangle & Adductor Canal - Pathway Prime

Femoral Triangle:

• Boundaries:
  • Superior: Inguinal ligament
  • Medial: Medial border of adductor longus
  • Lateral: Medial border of sartorius
  • Floor: Iliopsoas, pectineus, adductor longus
  • Apex: Junction of sartorius & adductor longus
• Contents (Lateral to Medial): 📌 NAVEL
  • Femoral Nerve
  • Femoral Artery
  • Femoral Vein
  • Empty space (Femoral canal)
  • Lymphatics (Deep inguinal nodes)

Adductor Canal (Hunter's / Subsartorial):

• Location: Deep to sartorius; from FT apex to adductor hiatus.
• Boundaries:
  • Anterolateral: Vastus medialis
  • Posteromedial: Adductors (longus & magnus)
  • Roof: Sartorius & subsartorial fascia
• Contents:
  • Femoral artery & vein
  • Saphenous nerve
  • Nerve to vastus medialis

⭐ The femoral artery enters the adductor canal and exits through the adductor hiatus, becoming the popliteal artery.

Posterior Thigh & Sciatic Nerve - Hamstring Highway

• Hamstring Muscles: "True" hamstrings:
  • Origin: Ischial Tuberosity.
  • Innervation: Tibial division of Sciatic N. (except short head Biceps Femoris).
  • Action: Hip extension, Knee flexion.
  • Muscles: Biceps Femoris (Long Head), Semitendinosus, Semimembranosus. (Adductor Magnus - hamstring part).
• Sciatic Nerve (Roots: L4-S3):
  • Exits pelvis via greater sciatic foramen (inferior to piriformis).
  • Course: Descends posterior thigh, deep to Biceps Femoris long head, superficial to Adductor Magnus.
  • Bifurcation: Tibial & Common Peroneal nerves (apex of popliteal fossa).
  • Innervates: Hamstrings, all muscles below knee (via branches).

⭐ The short head of biceps femoris is innervated by the common peroneal part of the sciatic nerve; not a 'true' hamstring (no ischial tuberosity origin). 📌 Mnemonic (Hamstring Actions): "Extend Hips, Flex Knees."

Popliteal Fossa - Diamond Domain

• Boundaries:

  • Superomedial: Semitendinosus, Semimembranosus
  • Superolateral: Biceps femoris
  • Inferomedial: Medial head of Gastrocnemius
  • Inferolateral: Lateral head of Gastrocnemius, Plantaris
  • Roof: Skin, popliteal fascia
  • Floor: Popliteal surface of femur, knee joint capsule, popliteus muscle

• Contents (Neurovascular bundle from superficial to deep):

  • Tibial nerve
  • Popliteal vein
  • Popliteal artery (deepest)
  • Common peroneal nerve (courses along lateral border)
  • 📌 Mnemonic (Main bundle, deep to superficial): Artery, Vein, Nerve (Popliteal A., Popliteal V., Tibial N.)
  • Termination of small saphenous vein, popliteal lymph nodes.

⭐ The popliteal artery, the deepest structure, lies on the femur and knee joint capsule, vulnerable in supracondylar fractures of the femur.

High‑Yield Points - ⚡ Biggest Takeaways

• Femoral triangle contents (lateral to medial): Femoral Nerve, Artery, Vein, Empty space, Lymphatics (NAVEL).
• Adductor canal transmits femoral artery & vein and the saphenous nerve.
• Profunda femoris artery is the main arterial supply to the thigh.
• Sciatic nerve bifurcates into tibial and common peroneal nerves within the popliteal fossa.
• Popliteal artery, the deepest structure, is prone to injury in supracondylar femur fractures.
• Popliteal fossa contents (superficial to deep): Nerves (Tibial & Common Peroneal), Vein, Artery.