Advanced Lumbar Plexus Quiz

Q1. Why can a psoas major lesion affect multiple lumbar plexus nerves?

• The sacral plexus is contained in the psoas tendon
• The spinal cord lies inside psoas major
• All lumbar nerves pass through rectus abdominis
• The lumbar plexus is embedded within psoas major

Q2. What motor deficit is most characteristic of a significant femoral nerve lesion proximal to the inguinal ligament?

• Weakness of knee extension
• Loss of ankle plantarflexion only
• Loss of toe flexion only
• Weakness of thigh adduction only

Q3. What motor deficit is most characteristic of an obturator nerve lesion?

• Weakness of shoulder abduction
• Weakness of knee extension
• Loss of ankle dorsiflexion
• Weakness of thigh adduction

Q4. Why can compression of the lateral femoral cutaneous nerve near the inguinal ligament cause meralgia paresthetica without motor weakness?

• It supplies quadriceps exclusively
• It is a sensory nerve without a motor component
• It carries only parasympathetic fibers
• It is part of the sympathetic trunk

Q5. Why is the femoral nerve vulnerable in the groove between psoas major and iliacus?

• It crosses the anterior surface of rectus abdominis
• It descends between psoas major and iliacus before entering the thigh
• It runs within the obturator canal
• It lies inside the femoral artery

Q6. Why can retroperitoneal hemorrhage involving the iliopsoas compartment produce femoral neuropathy?

• The nerve passes through the rectus sheath
• The nerve is contained in the renal pelvis
• The femoral nerve traverses the iliopsoas region and can be compressed there
• The femoral nerve runs inside the inferior vena cava

Q7. What anatomical feature distinguishes the femoral and obturator nerves in their formation from L2 to L4?

• Femoral is parasympathetic and obturator is sympathetic
• Femoral uses posterior divisions, while obturator uses anterior divisions
• Femoral arises from dorsal rami and obturator from ventral roots
• Femoral is L1 only and obturator is S1 only

Q8. Why is the lumbar plexus relevant during posterior abdominal wall and retroperitoneal surgery?

• Its branches are closely related to psoas major and retroperitoneal surgical planes
• It is confined to the anterior abdominal skin
• It runs only within the vertebral canal
• It lies entirely within the peritoneal cavity

Q9. How does the lumbar plexus connect functionally and anatomically with the sacral plexus?

• L2 joins the phrenic nerve
• L3 joins the sympathetic trunk to form the sciatic nerve
• L1 joins the vagus nerve
• L4 joins L5 through the lumbosacral trunk

Q10. Which statement best integrates the anatomy of the lumbar plexus?

• It is formed entirely by sacral spinal nerves
• It supplies only the posterior thoracic wall
• It is a purely autonomic plexus surrounding the celiac trunk
• It is an L1 to L4 somatic plexus within psoas major whose branches supply abdominal, inguinal, and lower limb territories