Nerves and blood vessels of the lower limb

Question 1

Which nerves make up the lumbar plexus?

Answer 1

T12-L5, even though T12 is from the thoracic spine, it does sometimes make a contribution to the lumbar plexus anyway.

Question 2

which muscle of the pelvis does the lumbar plexus emerge from?

Answer 2

The psoas muscle. The lumbar plexus is behind the psoas muscle and its roots come out from behind it.

Question 3

Where does the ilioinguinal nerve come out from psoas?

Answer 3

The Ilioinguinal nerve comes out from the top, lateral side of the psoas muscle. Then goes around the iliac crest of the pelvis and enters along the anterior superior iliac spine.

Question 4

where is the iliohypogastric nerve with respect to the psoas muscle?

Answer 4

it also comes off the topmost, lateral side of the psoas muscle, but then it cuts accross obliquely from the quadratus lumborum muscle.

Question 5

Which spinal segments do the ilioinguinal and iliohypogastric nerves come from?

Answer 5

L1- this is why they come off the topmost, lateral side of psoas major.

Question 6

where is the lateral cutaneous nerve with respect to the psoas muscle?

Answer 6

The lateral cutaneous arises from the L2 and L3. The nerve travels along the rim of the iliac spine and heads towards the anterior superior iliac spine, before dropping at the edge directly into the lateral side of the anterior thigh.

Question 7

Where is the femoral nerve with respect to the psoas muscle?

Answer 7

The femoral nerve arises from L2,3 and 4. It The three branches each of these spinal segments combine to form one single branch that run parralel and directly in front of the lower end of psoas. It passes under the inguinal canal and

Question 8

Where is the genitofemoral nerve with respect to the psoas muscle?

Answer 8

It is originates from L1 and 2, and arises from the anterior surface of the psoas muscle. It splits into two branches, a femoral branch and a genital branch. The femoral branch.

Question 9

Where is the obturator nerve with respect to the psoas muscle?

Answer 9

The obturator nerve arises from the L2,3 and 4, just like the femoral nerve. However, the obturator nerve emerges from the pelvis, on the medial side of the psoas muscle and drops into the obturator foramen to enter into the medial thigh.

Question 10

What does the femoral nerve innervate?

Answer 10

The femoral nerve is made up of the posterior divisions of L2,3 and 4.

skin: anterior, medial side of the thigh through the anterior cutaneous branches.

Muscles: Quadriceps, sartorius and pectineus.

Question 12

where does the saphenous nerve innervate?

(it is a branch of the femoral nerve)

Answer 12

The saphenous nerve arises in the femoral triangle and descends down the thigh, via the adductor canal. It exits the canal just before the adductor hiatus, crossing the medial aspect of the knee and passing deep to the sartorius tendon.

This sensory nerve supplies the skin on the medial side of the leg and foot.

Question 13

where are the anterior cutaneous branches of the femoral nerve?

Answer 13

The anterior cutaneous branches also arise in the femoral triangle.

These nerves innervate the skin of the anterior and medial aspects of the thigh.

Question 14

where is the lateral femoral cutaneous nerve?

Answer 14

The lateral femoral cutaneous nerve is responsible for innervating the lateral skin of the thigh.

It is an early branch of the femoral nerve, that enters the thigh on its own, by dropping down into the thigh from the ASIS (anterior superior iliac spine) and then under the inguinal ligament.

Question 15

what does the obturator nerve innervate?

Answer 15

Muscles: The adductor muscles in the medial compartment of the thigh.

Skin: inferior, medial skin of the thigh.

NOTE: pinching of the obturator nerve in the pelvis, before it comes out from the obturator foramen can occur from the presence of ovarian cysts squashing the nerve.

Pinching of the obturator nerve results in reffered pain to the inferior middle part of the thigh.

Question 16

where is the sciatic nerve found?

Answer 16

The sciatic nerve is the biggest nerve in the body. It is supplied by the L4&5 and S1-3 spinal roots.

From the pelvis, the sciatic nerve enters the thigh by slipping out from the greater sciatic foramen, underneath the piriformis muscle in the gluteal region.

It runs straight down the posterior compartment of the thigh and splits into two branches at the popliteal fossa for the leg.

Question 17

what does the sciatic nerve innervate?

Answer 17

Skin: nothing in the thigh, but it will branch off and the branches of the sciatic nerve will innervate the skin of the legs.

Muscle: the hamstrings, (except short head of biceps).

Question 18

where is the tibial nerve?

Answer 18

The tibial nerve is the posterior branch of the sciatic nerve. It is located at the posterior of the leg, and travels down towards the medial malleolus, where it passes behind it to enter the sole of the foot.

Question 19

what does the tibial nerve innervate?

Answer 19

The tibial nerve-

Muscles: all of posterior compartment of leg and sole of foot.

Skin: sole of foot, lateral side of the foot and the posterolateral side of the leg (sural nerve branch).

Question 20

where is the common fibular nerve?

Answer 20

It is a branch of the sciatic nerve.

From the popliteal fossa, it lies medially to the heads o gastrocnemius. It wraps around the head of the fibula and travels downwards to the foot.

Question 21

what does the common fibular nerve split into?

Answer 21

Common fibular becomes either the deep fibular or superficial fibular nerve.

Question 22

what does the superficial fibular nerve innervate?

Answer 22

Muscles:It innervates the lateral compartment muscles of the leg and dorsum of foot.

Skin:lateral leg and dorsum of foot.

Question 23

what does the deep fibular nerve do?

Answer 23

Muscle: innervates the anterior
compartment of leg.

Skin: sensory to 1st
toe cleft.

Question 24

What do the superior and inferior gluteal nerves innervate?

Answer 24

The gluteus muscles.

Question 25

Name all the dermatomes in the leg and which nerve roots they belong to.

Answer 25

read the labelled diagram

Question 26

Where is the femoral artery located and what does it supply?

Answer 26

Femoral artery comes off the external iliac artery of the pelvis. It enters the thigh via the femoral triangle.

It supplies the anterior thigh compartment.

It splits off to form a deep femoral artery, that supplies the posterior thigh compartment.

The deep femoral artery lies ontop of adductor magnus and has perforating branches to supply the posterior thigh muscles.

Question 27

Where is the popliteal artery and what does it supply?

Answer 27

The femoral artery travels within the femoral canal down the medial side of the thigh. It then enters a hole in adductor magnus called the adductor hiatus, so that it can move to the posterior compartment.

It ends up just above the knee on the posterior side and becomes the popliteal artery.

It supplies the knee joint via many anastomoses branches it gives off called the genicular arteries. It also supplies the calf muscles.

Question 28

Where is the anterior and posterior tibial arteries?

Answer 28

The popliteal artery splits into the anterior and posterior tibial arteries to supply the leg and foot.

The anterior tibial artery supplies the anterior compartment muscles. It then travels down into the dorsum of the foot and changes name to become the dorsalis pedis artery.

The posterior tibial artery supplies blood to the posterior compartment of the leg and the plantar surface of the foot (via medial and lateral planter arteries).

Question 29

Where is the fibular artery and what does it supply?

Answer 29

The posterior tibial artery actually gives off a lateral branch, called the fibular artery, before continuing down the posterior leg itself.

The fibular artery supplies the posterior leg also, and acts as a nutrient artery for the fibular bone.

Question 31

Where are the deep veins of the lower limb?

Answer 31

The deep veins of the lower limb have identical names and paths to the deep arteries.

Question 32

What are the key superficial veins in the lower limb?

Answer 32

The great saphenous vein runs down the medial thigh and medial leg, where it connects the dorsal venous arch to femoral vein, where it drains into.

The short saphenous vein is only in the leg, and also drains the dorsal venous arch before emptying into the popliteal vein and terminating there.