Body Spaces, Blood Supply & Nerve Supply of the Lower Limb

anterior tibial artery blood supply to lower limb body spaces of the lower limb common peroneal nerve deep peroneal nerve femoral artery femoral nerve lumbar plexus lumbosacral plexus medial and lateral plantar nerves nerve supply obturator nerve plexus popliteal artery posterior tibial artery sciatic nerve superficial peroneal nerve tibial nerve venous drainage

lower limb Blood Supply & Nerve Supply physiotherapy solihull simon evans

Body Spaces of the Lower Limb

  • Formed by the divergence of soft tissues (muscles and tendons)
  • Femoral triangle
    • Boundaries - inguinal ligament (base), sartorius (lateral border), medial border of adductor longus (medial border)
    • Floor - Pectineus, adductor brevis & longus
    • Contents - Femoral artery, vein & nerve, lymphatics
  • Popliteal Fossa
    • Boundaries 
      • Upper medial - medial hamstrings
      • Upper lateral - Biceps femoris
      • Lower medial - medial head of gastrocnemius
      • Lower lateral - lateral head of gastrocnemius
    • Floor - popliteus & knee joint capsule
    • Contents - Popliteal artery/vein, tibial nerve & lymphatics

Blood Supply to Lower Limb

  • Oxygenated blood from core reaches periphery via main arteries - branches given off at various levels
  • Deoxygenated blood returns to core via superficial and deep veins

Blood Supply to Lower Limb - Femoral Artery

  • Aorta divides into 2 common iliac arteries
  • Which divide into internal & external iliac arteries in pelvic bowl
  • Ext. iliac artery pass under inguinal ligament to form femoral artery
  • Most superficial in femoral triangle (pulse)
  • Passes down in the sub sartorial canal before passing posteriorly through the adductor hiatus

Blood Supply to Lower Limb - Popliteal Artery

  • Popliteal artery - continuation of femoral artery
  • Enters popliteal fossa under upper medial border at which point is most superficial (pulse)
  • Passes to inferior corner of fossa to run deep to gastrocnemius / soleus 
  • Divides into anterior and posterior tibial arteries

Blood Supply to Lower Limb - Anterior Tibial Artery

  • Anterior tibial artery passes though opening in upper interosseous membrane
  • Runs down in anterior compartment
  • At the ankle becomes the the Dorsalis Pedis artery which forms the dorsal arch supplying the foot and toes 
  • Pulses identifiable over anterior ankle and dorsum of foot

Blood Supply to Lower Limb - Posterior Tibial Artery

  • Larger division of popliteal artery
  • Passes under the superficial plantarflexors to run down in posterior compartment of leg
  • Run under foot behind medial malleolus (pulse) to form plantar arch supplying foot and toes

Blood Supply to Lower Limb - Venous Drainage

  • Deep venous system accompanies the arterial system - the smaller vessel run in pairs (venae commitantes)
  • Superficial venous system - from dorsal venous network form:
    • the Great (anteromedial) Saphenous vein - drains into Femoral vein in femoral triangle
    • and Small (posterolateral) Saphenous vein - drains into popliteal vein in popliteal fossa

Nerve Supply to Lower Limb

  • Spinal cord – housed in vertebral canal and divided into segment
  • Each segment forms ventral (motor) and dorsal (sensory) which join to form the nerve root (with fibres from the ANS)
  • Nerve root emerges via IV foramen below corresponding vertebra in Tx & Lu region & above in Cx region (C8 root emerges between C7 & T1)
  • Once beyond IV foramen roots divide into anterior and posterior primary rami
  • Posterior 1° rami pass to skin and muscle of the back
  • Anterior 1° rami pass forward to form the plexi
  • T12 to L4 form the Lumbar plexus
  • L4 to S4 form the Lumbosacral plexus

The Lumbar Plexus

  • Formed by the anterior 1° rami of T12 to L4 (L5)
  • Formed in the substance of psoas major
  • Main nerves arising include
    • Femoral nerve
    • Obturator nerve

Femoral Nerve - L2, 3 & 4

  • Femoral nerve - emerging from lateral border of psoas 
  • enters anterior compartment under inguinal ligament 
  • to supply muscle and skin on the anterior thigh (quads and sartorius)

Obturator Nerve - L2,3 & 4

  • Obturator nerve – emerging from medial border of psoas 
  • enters medial compartment through small opening in obturator membrane 
  • to supply muscles and skin of medial thigh (adductor compartment)

Lumbosacral Plexus

  • Formed by the anterior 1° rami of L4 to S4 
  • Formed in the substance of psoas major
  • Main nerves arising include
    • Tibial nerve
    • Common Peroneal nerve
    • (combine to form the Sciatic nerve)

Sciatic Nerve

  • Largest nerve in the body - formed by the union of  the tibial (L4 to S3) and common peroneal nerves (L4 to  S2)
  • Forms in pelvic bowl - emerges through grater sciatic notch under cover of piriformis
  • Passes down between hamstring supplying them (including ischial head of adductor magnus)
  • Ends at upper corner of popliteal fossa by dividing into its 2 terminal branches

Tibial Nerve (L4 to S3)

  • Larger division of the sciatic nerve
  • From upper corner of popliteal fossa 
  • Passes into posterior calf under soleus supplying posterior compartment
  • Lies behind medial malleolus (under flexor retinaculum)  at ankle before dividing into its terminal branches

Medial and Lateral Plantar Nerves

  • Terminal branches of tibial nerve enter foot under sustentaculum tali
  • Supply muscles and skin of sole of foot

Common Peroneal Nerve

  • Short and smaller division of sciatic nerve
  • Passes down upper lateral border of popliteal fossa under biceps femoris tendon
  • Winds around neck of fibula
  • Divides into its terminal branches 

Superficial Peroneal Nerve

  • Passes down in the lateral compartment of the lower leg
  • Supplies evertors of foot and skin over dorsum of foot (except ‘flip-flop’ area)
  • Most superficial over lateral collateral ligament of the ankle

Deep Peroneal Nerve

  • Passes from neck of fibula into the anterior compartment
  • Supplies the dorsiflexors of the foot and ankle and the ‘flip-flop’ area

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