Nerve supply of LL

Question 1

What is the hilton’s law?

Answer 1

A nerve that supplies muscles crossing a joint also supplies the joint.

Question 2

What forms the nerve supply of LL?

Answer 2

It arises from the lumbar plexus formed by ventral rami of L1-4. It is also formed by sacral plexus formed by lumbosacral trunk S1-4.

Lateral border of Psoas: Femoral N., lateral cutaneous nerve of thigh

Medial border of Psoas: obturator N.

Question 3

What does the femoral nerve innervate?

Answer 3

L2, 3, 4
originates from posterior abdominal wall
arise from posterior divisions of lumbar plexus

Lateral border of Psoas - passing underneath inguinal ligament

Anterior division of femoral n. (flex)

Muscular - sartorius
cutaneous - medial and intermediate cutaneous nerve of thigh

Posterior division of femoral n. (extension)

muscular - quads femoris
cutaneous - saphenous n. (below knee)

Question 4

What does the obturator nerve innervate? Clinical significance?

Answer 4

L2,3,4

from anterior divisions of lumbar plexus
medial border of Psoas - lateral wall of pelvis - obturator canal - medial compartment of thigh

anterior division of obturator n.
- add. longus, add. brevis, gracilis, pectineus (dual function and dual nerve supply)

post division of obturator n.

• add. brevis
• add. magnus

cutaneous supply: inferomedial thigh

Clinical significance: inflammation near pelvic region such as ovarian cyst - pain could be referred to medial side of thigh

Question 5

What does the sciatic nerve supply?

Answer 5

L4, 5, S1, 2, 3

anterior divisions of lumbar plexus and sacral plexus
it splits into tibial and common fibular nerves.

exits pelvis via greater sciatic foramen - emerge beneath piriformis in gluteal region - descends posterior to thigh - apex of popliteal fossa - tibial (passes down calf) + common fibular (passes laterally around neck of fibula)

Clinical significance: posterior dislocation of hip - loss of flexion of knee (interruption of motor supply to posterior thigh), sensation below knee impacted after posterior dislocation of hip - saphaneous n.
- intramuscular injections in gluteal region

Question 6

What does the tibial nerve supply?

Answer 6

L4, 5, S1, 2, 3
Anterior divisions of lumbar plexus and sacral plexus

upper apex of popliteal fossa - lower apex of popliteal fossa - beneath fibrous arch of soleus - descends on tibias posterior on calf - posterior to medial malleolus - enters tarsal tunnel beneath flexor retinaculum - sole of foot (medial and lateral plantar nerves)

Muscles:
posterior leg and sole of foot (plantar nerve)

cutaneous:
posterolateral leg
lateral side of foot (sural nerve)
sole of foot (medial, calcaneal, medial +lateral plantar nerves)

Tom, Dick and Very Naughty Harry.

tibialis posterior, flexor digitorum longus, post. tibial a. venae comitantes, tibial nerve, flexor hallucis longus

Question 7

What does the common fibular nerve supply?

Answer 7

anterior compartment of leg (extensor)
L4, 5, S1, 2 posterior divisions

upper lateral border of Pop. fossa (medial to biceps femoris) - superficial to lateral head of gastrocnemius - winds around neck of fibula - fibularis longus (lateral leg) - deep & superficial fibular nerve

deep fibular nerve - anterior compartment of leg
superficial fibular nerve - lateral leg, cutaneous innervation: lateral leg and dorsal of foot

clinical significance: fracture of fibula, foot drop, compression