Lecture 17: Neurovasculature of the Lower Limb Flashcards
What does the lumbosacral plexus consist of?
upper lumbar plexus (L1-4) and lower lumbosacral (L4-S3) plexus
What is the role of the lumbosacral plexus?
supplies sensory and motor innervation to lower limb
What do ventral rami give rise to?
anterior and posterior divisions
Which nerves emerge from the lateral border of psoas?
iliohypogastric and ilioinguinal nerve
lateral cutaneous nerve of thigh
femoral
Which nerve passes over the anterior surface of psoas?
genitofemoral nerve
Which nerve emerges from the medial border of psoas?
obturator nerve
What is the largest branch of the lumbar plexus?
the femoral nerve
What does the femoral nerve supply motor innervation to?
iliopsoas + anterior compartment muscles (sartorius, quadriceps) and pectineus
What does the femoral nerve supply cutaneous innervation to?
anteromedial thigh (anterior cutaneous nerve) and medial leg and hindfoot (saphenous nerve)
What is the path of the obturator nerve?
descends behind and medial to psoas; passes through obturator canal within the obturator foramen
What does the obturator nerve supply motor innervation to?
muscles of the medial compartment of the thigh (and sometimes pectineus)
What does the obturator nerve supply cutaneous innervation to?
inferomedial thigh
Where does the sciatic nerve exit the pelvis?
via greater sciatic foramen, deep to gluteus maximus, commonly below piriformis
Where does the sciatic nerve commonly split?
at popliteal fossa apex
What is the path of the tibial part of the sciatic nerve?
descends along posterior thigh and leg, behind medial malleolus deep to flexor retinaculum, to plantar aspect of foot (medial and lateral plantar nerves)
What does the tibial part of the sciatic nerve supply motor innervation to?
muscles of posterior compartment of thigh and leg, intrinsic muscles of foot
What does the tibial part of the sciatic nerve supply cutaneous innervation to?
posterior leg and lateral foot (sural nerve) and plantar foot
What are the two terminal branches of the fibular part of the sciatic nerve?
superficial fibular nerve and deep fibular nerve
What does the superficial fibular nerve supply innervation to?
motor: lateral compartment of leg
cutaneous: lower lateral leg and dorsum of foot
What does the deep fibular nerve supply innervation to?
motor: muscles of anterior compartment of leg and foot (EDB, EHB)
cutaneous: cleft between great and 2nd toe
How are peripheral nerves damaged?
injury (e.g. falls) or medical conditions (diabetic neuropathy)
What are the signs and symptoms of peripheral nerve damage?
sensory loss (weakness, numbness, pain) motor loss (paralysis or paresis) signs and symptoms are distal to the lesion
What happens as the lower limb develops?
lower limb rotates medially
How can the sciatic nerve be injured in a clinical setting?
can be injured by an incorrectly placed IM injection in the gluteal region resulting in hamstring paralysis, impaired leg function and foot drop
What are characteristics of superficial veins of the lower limb?
larger, fewer one-way valves, within superficial fascia; drain skin and superficial fascia; approx. 10% venous return
What are characteristics of deep veins of the lower limb?
paired venae comitantes accompany smaller arteries in distal areas; many one-way valves; approx. 90% venous return
What is the role of perforating veins?
perforate deep fascia of muscles to allow blood to flow from superficial to deep veins; possess one-way valves
What is an example of a factor that promotes venous return?
the muscle pump system
What is the great saphenous vein formed from?
medial dorsal venous arch (medial malleolus)
What is the small saphenous vein formed from?
lateral dorsal venous arch (lateral malleolus)
How is blood carried from the foot back to the heart?
deep veins on dorsum of foot -> anterior tibial vein -> popliteal vein -> femoral vein
What occurs during venous disease?
valves become incompetent and blood flows back into superficial system
as a result veins become engorged, swollen and tortuous
Where do superficial lymphatic vessels lie?
in the skin and subcutaneous tissues
frequently accompany superficial veins
What do superficial veins drain into?
deep lymphatic vessels at constant sites in the limbs
What do deep vessels drain?
areas deep to the fascia and accompany deep veins of the region
What are two major deep nodes?
deep popliteal and deep inguinal nodes
How is blood supplied to the lower limb?
abdominal aorta -> common iliac artery -> external iliac artery -> femoral artery -> popliteal artery -> anterior / posterior tibial artery -> dorsal pedal / medial and lateral plantar / fibular arteries
What are the arteries of the gluteal region?
superior and inferior gluteal arteries
What is the femoral artery?
continuation of external iliac artery once passes under the inguinal ligament
What is the path of the femoral artery?
travels down anteromedial aspect of the thigh, then through adductor canal -> passes through adductor hiatus to become popliteal artery
What does the profunda femoris artery branch from?
the lateral aspect of the femoral artery, coursing inferiorly on the medial aspect of the femur
What are the three major branches of the profunda femoris artery?
lateral circumflex, medial circumflex and perforating femoral artery
What are the arteries of the foot?
medial plantar artery, lateral plantar artery (deep plantar arch)
dorsalis pedis artery, arcuate artery
