The Lumbosacral Plexus

Question 1

What structures form the lumbosacral plexus?

Answer 1

The lumbosacral plexus is formed by the ventral rami of spinal nerves L1-S4.

Question 2

Where is the lumbosacral plexus located in the body?

Answer 2

The lumbosacral plexus is located in the pelvic region, extending from the lumbar spine to the sacrum.

Question 3

What are the main nerves arising from the lumbosacral plexus?

Answer 3

The main nerves arising from the lumbosacral plexus include the femoral nerve, obturator nerve, sciatic nerve, and their branches.

Question 4

Describe the course and distribution of the femoral nerve.

Answer 4

The femoral nerve courses through the pelvis and thigh, supplying motor innervation to the anterior thigh muscles and sensory innervation to the anterior thigh and medial leg.

Question 5

What muscles does the femoral nerve innervate?

Answer 5

The femoral nerve innervates muscles such as the quadriceps femoris and sartorius.

Question 6

Describe the course and distribution of the obturator nerve.

Answer 6

The obturator nerve passes through the pelvis and innervates the medial thigh muscles, including the adductors.

Question 7

What muscles does the obturator nerve innervate?

Answer 7

The obturator nerve innervates muscles such as the adductor longus and gracilis.

Question 8

Describe the course and distribution of the sciatic nerve.

Answer 8

The sciatic nerve is the largest nerve of the lumbosacral plexus, supplying motor and sensory innervation to the posterior thigh, leg, and foot.

Question 9

What muscles does the sciatic nerve innervate?

Answer 9

The sciatic nerve innervates muscles such as the hamstrings and muscles of the lower leg and foot.

Question 10

What are the two main branches of the sciatic nerve?

Answer 10

The two main branches of the sciatic nerve are the tibial nerve and the common fibular (peroneal) nerve.

Question 11

Describe the course and distribution of the tibial nerve.

Answer 11

The tibial nerve travels down the posterior thigh and leg, supplying motor innervation to the posterior thigh muscles and sensory innervation to the posterior leg and sole of the foot.

Question 12

What muscles does the tibial nerve innervate?

Answer 12

The tibial nerve innervates muscles such as the gastrocnemius and soleus.

Question 13

Describe the course and distribution of the common fibular (peroneal) nerve.

Answer 13

The common fibular (peroneal) nerve divides into the deep fibular nerve and superficial fibular nerve, supplying motor innervation to the anterior and lateral compartments of the leg, respectively.

Question 14

What muscles does the common fibular nerve innervate?

Answer 14

The common fibular nerve innervates muscles such as the tibialis anterior and fibularis longus.

Question 15

Describe the course and distribution of the superior gluteal nerve.

Answer 15

The superior gluteal nerve exits the pelvis and innervates the gluteus medius, gluteus minimus, and tensor fasciae latae.

Question 16

What muscles does the superior gluteal nerve innervate?

Answer 16

The superior gluteal nerve innervates muscles responsible for hip abduction and stabilization.

Question 17

Describe the course and distribution of the inferior gluteal nerve.

Answer 17

The inferior gluteal nerve exits the pelvis and innervates the gluteus maximus.

Question 18

What muscles does the inferior gluteal nerve innervate?

Answer 18

The inferior gluteal nerve innervates the largest muscle of the buttocks, responsible for hip extension and lateral rotation.

Question 19

Describe the course and distribution of the pudendal nerve.

Answer 19

The pudendal nerve exits the pelvis and innervates the perineum, including the external genitalia and anal region.

Question 20

What muscles does the pudendal nerve innervate?

Answer 20

The pudendal nerve innervates muscles such as the external anal sphincter and bulbospongiosus.

Question 21

Describe the course and distribution of the posterior femoral cutaneous nerve.

Answer 21

The posterior femoral cutaneous nerve travels down the posterior thigh and innervates the skin of the posterior thigh and popliteal fossa.

Question 22

What areas does the posterior femoral cutaneous nerve innervate?

Answer 22

The posterior femoral cutaneous nerve innervates the skin of the posterior thigh, buttocks, and perineum.

Question 23

Describe the course and distribution of the iliohypogastric nerve.

Answer 23

The iliohypogastric nerve exits the pelvis and innervates the skin of the lower abdomen, inguinal region, and gluteal region.

Question 24

What areas does the iliohypogastric nerve innervate?

Answer 24

The iliohypogastric nerve innervates the skin over the iliac crest, pubic symphysis, and upper buttock.

Question 25

Describe the course and distribution of the ilioinguinal nerve.

Answer 25

The ilioinguinal nerve exits the pelvis and innervates the skin of the inguinal region, mons pubis, and upper scrotum or labia majora.

Question 26

What areas does the ilioinguinal nerve innervate?

Answer 26

The ilioinguinal nerve innervates the skin over the groin, upper thigh, and external genitalia.

Question 27

Describe the course and distribution of the genitofemoral nerve.

Answer 27

The genitofemoral nerve exits the pelvis and innervates the skin of the genitalia and anterior thigh.

Question 28

What areas does the genitofemoral nerve innervate?

Answer 28

The genitofemoral nerve innervates the skin over the anterior thigh and genital region.

Question 29

Describe the course and distribution of the lateral femoral cutaneous nerve.

Answer 29

The lateral femoral cutaneous nerve exits the pelvis and innervates the skin of the lateral thigh.

Question 30

What areas does the lateral femoral cutaneous nerve innervate?

Answer 30

The lateral femoral cutaneous nerve innervates the skin over the lateral thigh, providing sensory innervation.