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