Week 28 - Lower Limb

Question 1

Which of the following muscles receives its motor innervation from the femoral nerve?

• a) Adductor longus
• b) Psoas major
• c) Vastus medialis
• d) Biceps femoris
• e) Piriformis

Answer 1

• a) Adductor longus = obturator nerve
• b) Psoas major = Anterior rami of L1 – L3 nerves.
• c) Vastus medialis
• d) Biceps femoris = Long head innervated by the tibial part of the sciatic nerve, whereas the short head is innervated by the common fibular part of the sciatic nerve.
• e) Piriformis = posterior division of the ventral rami of the S1 & S2 (sacral plexus)

Femoral Nerve

• Nerve roots: L2-L4
• Motor functions: Innervates the anterior thigh muscles that flex the hip joint (pectineus, iliacus, sartorius) and extend the knee (quadriceps femoris: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius),
• Sensory functions: Supplies cutaneous branches to the anteromedial thigh (anterior cutaneous branches of the femoral nerve) and the medial side of the leg and foot (saphenous nerve).

Question 2

A 19-year-old man suffers a traumatic posterior hip dislocation in a high-speed motor vehicle accident. Name the major nerve that is at risk in this injury.

Answer 2

= Sciatic nerve

Question 3

The medial, lateral and posterior cords of the brachial plexus are named relative to what vessel?

Answer 3

Once the anterior and posterior divisions have entered the axilla, they combine together to form three cords, named by their position relative to the axillary artery.

Question 4

Which of the following peripheral nerves would be most affected in a complete lesion of the lateral cord of the brachial plexus?

• a) Median nerve
• b) Radial nerve
• c) Ulnar nerve
• d) Axillary nerve
• e) Long thoracic nerve

Answer 4

• a) Median nerve
• b) Radial nerve
• c) Ulnar nerve
• d) Axillary nerve
• e) Long thoracic nerve

Question 5

The obturator nerve arises from the ……………….. divisions of the ventral rami of the spinal levels …………… and supplies the muscles of the ………………… compartment of the thigh. This differs from the femoral nerve, which arises from the ……………… divisions of the ventral rami of spinal levels …………………… and supplies muscles of the ……………………… compartment of the thigh.

Answer 5

LUMBAR PLEXUS

The obturator nerve arises from the anterior divisions of the ventral rami of the spinal levels L2, L3, L4 and supplies the muscles of the medial compartment of the thigh.

This differs from the femoral nerve, which arises from the anterior divisions of the ventral rami of spinal levels L2, L3, L4 and supplies muscles of the anterior compartment of the thigh.