Lecture 17: Neurovasculature of the Lower Limb

Question 1

What does the lumbosacral plexus consist of?

Answer 1

upper lumbar plexus (L1-4) and lower lumbosacral (L4-S3) plexus

Question 2

What is the role of the lumbosacral plexus?

Answer 2

supplies sensory and motor innervation to lower limb

Question 3

What do ventral rami give rise to?

Answer 3

anterior and posterior divisions

Question 4

Which nerves emerge from the lateral border of psoas?

Answer 4

iliohypogastric and ilioinguinal nerve
lateral cutaneous nerve of thigh
femoral

Question 5

Which nerve passes over the anterior surface of psoas?

Answer 5

genitofemoral nerve

Question 6

Which nerve emerges from the medial border of psoas?

Answer 6

obturator nerve

Question 7

What is the largest branch of the lumbar plexus?

Answer 7

the femoral nerve

Question 8

What does the femoral nerve supply motor innervation to?

Answer 8

iliopsoas + anterior compartment muscles (sartorius, quadriceps) and pectineus

Question 9

What does the femoral nerve supply cutaneous innervation to?

Answer 9

anteromedial thigh (anterior cutaneous nerve) and medial leg and hindfoot (saphenous nerve)

Question 10

What is the path of the obturator nerve?

Answer 10

descends behind and medial to psoas; passes through obturator canal within the obturator foramen

Question 11

What does the obturator nerve supply motor innervation to?

Answer 11

muscles of the medial compartment of the thigh (and sometimes pectineus)

Question 12

What does the obturator nerve supply cutaneous innervation to?

Answer 12

inferomedial thigh

Question 13

Where does the sciatic nerve exit the pelvis?

Answer 13

via greater sciatic foramen, deep to gluteus maximus, commonly below piriformis

Question 14

Where does the sciatic nerve commonly split?

Answer 14

at popliteal fossa apex

Question 15

What is the path of the tibial part of the sciatic nerve?

Answer 15

descends along posterior thigh and leg, behind medial malleolus deep to flexor retinaculum, to plantar aspect of foot (medial and lateral plantar nerves)

Question 16

What does the tibial part of the sciatic nerve supply motor innervation to?

Answer 16

muscles of posterior compartment of thigh and leg, intrinsic muscles of foot

Question 17

What does the tibial part of the sciatic nerve supply cutaneous innervation to?

Answer 17

posterior leg and lateral foot (sural nerve) and plantar foot

Question 18

What are the two terminal branches of the fibular part of the sciatic nerve?

Answer 18

superficial fibular nerve and deep fibular nerve

Question 19

What does the superficial fibular nerve supply innervation to?

Answer 19

motor: lateral compartment of leg
cutaneous: lower lateral leg and dorsum of foot

Question 20

What does the deep fibular nerve supply innervation to?

Answer 20

motor: muscles of anterior compartment of leg and foot (EDB, EHB)
cutaneous: cleft between great and 2nd toe

Question 21

How are peripheral nerves damaged?

Answer 21

injury (e.g. falls) or medical conditions (diabetic neuropathy)

Question 22

What are the signs and symptoms of peripheral nerve damage?

Answer 22

sensory loss (weakness, numbness, pain)
motor loss (paralysis or paresis)
signs and symptoms are distal to the lesion

Question 23

What happens as the lower limb develops?

Answer 23

lower limb rotates medially

Question 24

How can the sciatic nerve be injured in a clinical setting?

Answer 24

can be injured by an incorrectly placed IM injection in the gluteal region resulting in hamstring paralysis, impaired leg function and foot drop

Question 25

What are characteristics of superficial veins of the lower limb?

Answer 25

larger, fewer one-way valves, within superficial fascia; drain skin and superficial fascia; approx. 10% venous return

Question 26

What are characteristics of deep veins of the lower limb?

Answer 26

paired venae comitantes accompany smaller arteries in distal areas; many one-way valves; approx. 90% venous return

Question 27

What is the role of perforating veins?

Answer 27

perforate deep fascia of muscles to allow blood to flow from superficial to deep veins; possess one-way valves

Question 28

What is an example of a factor that promotes venous return?

Answer 28

the muscle pump system

Question 29

What is the great saphenous vein formed from?

Answer 29

medial dorsal venous arch (medial malleolus)

Question 30

What is the small saphenous vein formed from?

Answer 30

lateral dorsal venous arch (lateral malleolus)

Question 31

How is blood carried from the foot back to the heart?

Answer 31

deep veins on dorsum of foot -> anterior tibial vein -> popliteal vein -> femoral vein

Question 32

What occurs during venous disease?

Answer 32

valves become incompetent and blood flows back into superficial system as a result veins become engorged, swollen and tortuous

Question 33

Where do superficial lymphatic vessels lie?

Answer 33

in the skin and subcutaneous tissues | frequently accompany superficial veins

Question 34

What do superficial veins drain into?

Answer 34

deep lymphatic vessels at constant sites in the limbs

Question 35

What do deep vessels drain?

Answer 35

areas deep to the fascia and accompany deep veins of the region

Question 36

What are two major deep nodes?

Answer 36

deep popliteal and deep inguinal nodes

Question 37

How is blood supplied to the lower limb?

Answer 37

abdominal aorta -> common iliac artery -> external iliac artery -> femoral artery -> popliteal artery -> anterior / posterior tibial artery -> dorsal pedal / medial and lateral plantar / fibular arteries

Question 38

What are the arteries of the gluteal region?

Answer 38

superior and inferior gluteal arteries

Question 39

What is the femoral artery?

Answer 39

continuation of external iliac artery once passes under the inguinal ligament

Question 40

What is the path of the femoral artery?

Answer 40

travels down anteromedial aspect of the thigh, then through adductor canal -> passes through adductor hiatus to become popliteal artery

Question 41

What does the profunda femoris artery branch from?

Answer 41

the lateral aspect of the femoral artery, coursing inferiorly on the medial aspect of the femur

Question 42

What are the three major branches of the profunda femoris artery?

Answer 42

lateral circumflex, medial circumflex and perforating femoral artery

Question 43

What are the arteries of the foot?

Answer 43

medial plantar artery, lateral plantar artery (deep plantar arch) dorsalis pedis artery, arcuate artery