Nerves of the lower limb

Question 1

What is the lumbar plexus?

Answer 1

A network of nerve fibres that supplies the skin and musculature of the lower limb. Located within the lumbar region it sits within the substance of psoas major. Its roots are the anterior rami of L1-L4 with some innervation from T12

Question 2

What are the branches of the lumbar plexus

Answer 2

iliohypogastric nerve
ilioinguinal nerve
Genitofemoral nerve
lateral cutaneous nerve of the thigh
obturator nerve
femoral nerve

Question 3

What are the roots of the iliohypogastric nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 3

L1 (with contributions from L12)

Innervates the internal oblique and transverses abdominis

Innervates posterolateral gluteal skin in the pubic region

Question 4

What are the roots of the ilioinguinal nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 4

L1

Innervated the interal oblique and transversus abdominis muscle

Innervates skin on the upper medial thigh. In males it also supplies the skin of the root of the enis, in females the labia majora

Question 5

What are the roots of the genitofemoral nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 5

L1, L2

The genital branch innervates the cremasteric muscle

The genital branch innervates the skin of the anterior scrotum or the skin over the mons pubis and labia majora. Also does upper anterior thigh

Question 6

What are the roots of the lateral cutaneous nerve of the thigh

What are its motor functions?

What are it sensory innervation’s?

Answer 6

L2, L3

None

Innervates the anterior and lateral thigh down to the level of the knee

Question 7

What are the roots of the obturator nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 7

L2,L3,L4

Innervates the muscles: obturator externus, pectineus, adductor longus.adductor brevis adductor magnus and gracilis

Question 8

Describe the anatomical course of the obturator nerve

Answer 8

Travels past the psoas major and past the common ilaic arteries before going along the pelvic wall and out the obturator foramen of the obturator canal. Very small nerve with little branching

Question 9

What are the roots of the femoral nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 9

L2,L3,L4

Innervates the iliacus, pectineus, sartorius and muscles of quadriceps femoris

Innervates skin on the anterior thigh adn medial leg

Question 10

Describe the anatomical course of the femoral nerve

Answer 10

Largest branch of the lumbar plexus, runs down the psoas major muscle of the posterior abdominal wall. Travels under the inguinal ligament into the femroal triangle
Runs down the medial aspect of the thigh where is terminal branches terminate around the branch of the knee

Question 11

Desribe the sciatic nerve

Answer 11

The sciatic nerve is a major nerve of the lower limb. It is a thick flat band, approximetely 2cm wide- largest nerve in the body

Question 12

What are the roots of the sciatic nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 12

L4-S3

Innervates muscles of posterior thigh, indiractly innervates all the muscles of the leg and foot through its branches

No direct sensory functions

Question 13

Describe the anatomical course of the sciatic nerve

Answer 13

Arises from lumbosacral plexus. Leaves pelvis and enters gluteal region. Emerges underneath piriformis and travels inferiorly. Terminates int eh popliteal nerve where its gives rise to the tibial and common fibular nerves

Question 14

What is piriformis syndrome?

Answer 14

Compression of the sciatic nerve, also known as deep gluteal syndrome. Includes pain, numbness muscle wekaness and buttocks tenderness.

Question 15

Describe the tibial nerve

What are its roots?

What are its motor functions?

What are it sensory innervation’s?

Answer 15

posterior branch of the sciatic nerve

L4-S3

innervates posterior leg and majority of intrinsic foot muscles

Skin of posterolateral leg, lateral and sole of foot

Question 16

Describe the anatomical course of the tibial nerve

Answer 16

Runs straight don the back of the leg pretty much in a straight line

Question 17

Describe the common fibular nerve

What are the roots of the common fibular nerve?

What are its motor functions?

What are it sensory innervation’s?

Answer 17

Begins at the apex of the popliteal fossa, branch of sciatic nerve. Very short nerve that wraps around the knee

L4-S2

Inenrvates short head of biceps femoris

Skin over upper and lateral and lower posterolateral leg

Question 18

What happens during damage to the common fibular nerve

Answer 18

Very common during fracture of the fibula or use of a tight plaster cast

Causes patients to lose the ability to dorsiflex the foot

Question 19

Describe the superficial fibular nerve

What are the roots of it

What are its motor functions?

What are it sensory innervation’s?

Answer 19

Branch of common fibuar that runs medially down from knee to foot

L4-S1

Inenrvates muscles in lateral compartment of leg

Supplies the vast majority of the skin over the dorsum of the foot. Also anterior and lateral aspect of inferior third of leg

Question 20

What can ankle sprains lead to

Answer 20

Stretching of the superficial fibular nerve leading to pain and paraesthesia over the lower leg and dorsum of foot

Question 21

Describe the deep fibular nerve

What are the roots of the femoral nerve

What are its motor functions?

What are it sensory innervation’s?

Answer 21

Branch of ccommon fibular, starts at knee and runs straight down the leg through the middle of the ankle into the foot

L4- S1

Innervates muscles of anterior leg as well as some intrinsic msucles of the foot

Supplies the triangluar region of the skin between 1st and 2nd toes