Station 3: Neurovasculature of the lower limbs

Question 1

Where does the external iliac artery become the femoral artery?

Answer 1

Crosses under the inguinal ligament and enters the femoral triangle

Question 2

Where does the femoral artery become the popliteal artery?

Answer 2

Popliteal fossa

Question 3

Where does the popliteal artery normally bifurcate into the anterior tibial artery and tibioperoneal trunk (posterior tibial and fibular arteries)?

Answer 3

Lower border of the popliteus

Question 4

Where are the anterior and posterior tibial arteries located?

Answer 4

Posterior tibial artery continues inferiorly (posterior of leg) along surface of deep muscles, accompanies the tibial nerve in entering the sole of the foot
Anterior tibial artery passes anteriorly between tibia and fibula, through the interosseous membrane, then becomes dorsalis pedis artery in the foot.

Question 5

What are the common sites for compression of the arteries of the lower limb to prevent haemorrhage?

Answer 5

Femoral artery - superficially within the femoral triangle

Question 6

What are the borders of the femoral triangle?

Answer 6

Superior: inguinal ligament (runs from anterior superior inguinal spine to the pubis tubercle)
Lateral: medial border of sartorius
Medial: medial border of adductor longus

Question 7

Which structures run in the femoral triangle?

Answer 7

Femoral nerve
Femoral artery
Femoral vein (great saphenous drains here)
Femoral canal (deep lymph nodes and vessels)

Question 8

Which structures run within the fascial compartment known as the femoral sheath?

Answer 8

Femoral artery
Femoral vein
Femoral canal

Question 9

How would you locate the femoral vein in a patient without ultrasound?

Answer 9

Medial to pulsatile femoral artery

Nb NAVEL

Question 10

Where does the sciatic nerve originate?

Answer 10

Lumbosacral plexus: L4-S3

Question 11

What is the course of the sciatic nerve?

Answer 11

It leaves the pelvis and enters the gluteal region via the greater sciatic foramen -> posterior thigh -> apex of popliteal fossa (terminates here into the tibial and common fibular nerves)

Question 12

What are the motor and sensory functions of the sciatic nerve?

Answer 12

Motor:
DIRECTLY: Posterior compartment of the thigh, hamstring portion of adductor magnus (hip extension) - hip extension
INDIRECTLY: via tibial nerve (posterior leg and some intrinsic muscles of foot), via common fibular nerve (anterior leg, lateral leg, remaining intrinsic foot muscles) - knee flexion, all ankle and foot movements?

Sensory:
No direct sensory
INDIRECT - via tibial nerve (posterolateral and anterolateral sides of leg, plantar (sole) surface of foot), via common fibular nerve (lateral leg and dorsal surface of foot)

Question 13

Where is the sciatic nerve commonly injured?

Answer 13

Posterior to hip joint in gluteal region with posterior dislocation of the hip

Question 14

What are the roots of the femoral nerve?

Answer 14

L2-L4

Enters the pelvis under the mid-point of the inguinal ligament

Question 15

What are the motor functions of the femoral nerve?

Answer 15

Anterior thigh (flex hip)
Quadriceps femoris (extend the knee)

Question 16

What are the sensory functions of the femoral nerve?

Answer 16

Anteriomedial thigh

Medial side of the leg and foot (saphenous nerve)

Question 17

Where is the common injury site of the femoral nerve?

Answer 17

Not sure tbh!

Think it is uncommon but lets go - directly injury to the femoral triangle e.g. stab or would a pelvic fracture do it

Question 18

What are the nerve roots for the tibial nerve?

Answer 18

L4-S3

Question 19

What are the sensory functions of the tibial nerve?

Answer 19

Skin of the posterolateral side of the leg, lateral side of the foot, sole of the foot

Question 20

What are the motor functions of the tibial nerve?

Answer 20

Posterior compartment of the leg - flex toes, plantar flexes ankle, flex knee, assists inversion of foot

Question 21

Where would you damage the tibial nerve?

Answer 21

Posterior to medial malleolus (tibial nerve compressed within the tarsal tunnel - could happen post-trauma ankle deformities)

Question 22

What clinical manifestations would you have with a damage to the tibial nerve?

Answer 22

Loss of plantar flexion, loss of flexion of toes and weakened inversion

Question 23

What are the nerve roots of the common fibular nerve?

Answer 23

L4 - S3

Question 24

What are the motor functions of the common fibular nerve?

Answer 24

DIRECTLY: Short head of biceps femoris
INDIRECTLY: muscles in lateral and anterior compartments of the leg

Question 25

What are the sensory functions of the common fibular nerve?

Answer 25

Skin over the upper lateral and lower posterolateral leg.

Via branches - skin on the anterolateral leg, dorsum of foot

Question 26

What is the course of common fibular nerve?

Answer 26

Begins in the apex of the popliteal fossa (sciatic nerve bifurcates into the tibial and common fibular nerves) -> lateral compartment of leg -> wraps around neck of fibula -> terminates dividing into superficial and deep fibular nerves

Question 27

Where is the common fibular nerve often damaged? What are the associated clinical manifestations?

Answer 27

Fracture of the fibula

Lose ability to dorsiflex the foot at the ankle joint = foot drop

Loss of sensation over the dorsum of the foot and lateral sit of the leg

Question 28

What are the nerve roots of the superficial fibular nerve?

Answer 28

L4-S1

Question 29

What are the motor innervations of the superficial fibular nerve?

Answer 29

Lateral compartment of the leg - evert the foot (subtalar joint), weakly contribute to plantarflexion

Question 30

What are the sensory innervations of the superficial fibular nerve?

Answer 30

Dorsum of the foot (apart from webbing between the hallux and second digit)
Anterior and lateral aspect of inferior third of the leg
Correspond to dermatomes L5 and S1

Question 31

Where can the superficial fibular nerve be damaged and what are the clinical manifestations?

Answer 31

Fracture of the fibula or by perforating wound to the lateral side of the leg

Loss of eversion
Loss of sensation over the majority of dorsum of the foot and anterolateral aspect of the lower leg

Question 32

What are the nerve roots of the deep fibular nerve?

Answer 32

L4 and L5

Question 33

What are the motor functions of the deep fibular nerve?

Answer 33

Anterior compartment of the leg, and some intrinsic muscles of the foot (dorsiflexion of the foot, extending toes at the MTP joins and ITP joints)

Question 34

What are the sensory functions of the deep fibular nerve?

Answer 34

Triangular region of the skin between 1st and 2nd toes

Question 35

What would happen in damage to the deep fibular nerve?

Answer 35

Foot drop - can’t dorsiflex the foot

Question 36

What are the clinical manifestations of a posterior dislocation of the hip?

Answer 36

Shortened and internally rotated leg
Caused by high impact force
9 in 10 hip dislocations

Question 37

What nerve may get damaged in a posterior dislocation of the hip?

Answer 37

Sciatic nerve

Question 38

Why is compartment syndrome more common in the anterior compartment of the leg?

Answer 38

This is a good question, one that I do not know. It looks as though there are more muscles and in a smaller amount of space, gettin all squished up in there