Lumbar plexus (dave's notes)

Question 1

From what does the lumbar plexus arise and via what route?

Answer 1

The anterior rami of the upper four lumbar vertebrae segmentally supply quadratus lumborum and psoas, then form a plexus

Question 2

What does the lumbar plexus supply?

Answer 2

Primarily concerned with supplying skin and muscle “borrowed from the trunk”??? but also anterior abdominal wall. Also makes significant contributions to the sacral plexus.

Question 3

What is the nerve root that iliohypogastric and ilioinguinal arise from?

Answer 3

L1

Question 4

Which aspect of psoas do iliohypogastric and ilioinguinal nerves arise from?

Answer 4

Lateral

Question 5

Describe the iliohypogastric and ilioinguinal nerves

Answer 5

Really part of the first lumbar segmental body-wall nerve and its collateral

Question 6

What do the iliohypogastric and ilioinguinal nerves supply?

Answer 6

skin over the inguinal region, the front of the scrotum, internal oblique muscle and transversus abdominus muscle

Question 7

What is the nerve root that the genitofemoral nerve arises from?

Answer 7

L1,2

Question 8

Which aspect of psoas does the genitofemoral nerve arise from?

Answer 8

Anterior

Question 9

Describe the genitofemoral nerve and what it supplies

Answer 9

L1 is the femoral part, supplying the skin below the middle of the inguinal ligament. L2 is the genital part supplying the tunica vaginalis, spermatic fascia and cremaster muscle

Question 10

List the nerves of the lumbar plexus

Answer 10

Iiliohypogastric and ilioinguinal
Genitofemoral
Lateral femoral cutaneous
Femoral
Obturator

Question 11

From what nerve roots does the lateral femoral cutaneous nerve arise?

Answer 11

L2, 3, (posterior divisions)

Question 12

From what aspect of psoas does the lateral femoral cutaneous nerve arise?

Answer 12

Lateral

Question 13

What does the lateral femoral cutaneous nerve supply?

Answer 13

It is wholly sensory to the iliac fascia and peritoneum of the iliac fossa and the lateral side of the thigh down to the knee

Question 14

From what nerve roots does the femoral nerve arise?

Answer 14

L2,3,4 (posterior divisions)

Question 15

From what aspect of psoas does the femoral nerve arise?

Answer 15

Lateral

Question 16

Briefly describe the course of the femoral nerve

Answer 16

It crosses between psoas and iliacus, where it divides into 9-10 branches; superior and deep

Question 17

From what nerve roots does the obturator nerve arise?

Answer 17

L2,3,4

Question 18

From what aspect of psoas does the obturator nerve arise?

Answer 18

Medially

Question 19

Describe the course of the obturator nerve

Answer 19

The obturator nerve lies on the ala of the sacrum slanting down on the side wall of the pelvis, and from the angle of the internal iliac artery and external iliac artery it runs to the obturator foramen splitting anteriorly and posteriorly

Question 20

List the superficial branches of the femoral nerve and what they supply

Answer 20

Nerve to pectineus - to the muscle
Nerve to sartorius - to the muscle and then continues on as the intermediate femoral cutaneous nerve
Intermediate femoral cutaneous nerve - pierces sartorius and supplies skin and fascia kata over the front of the thigh
Medial femoral - supplies the medial side of the thigh plus knee

Question 21

List the deep branches of the femoral nerve and what they supply

Answer 21

Nerve to rectus femoris - usually x2 and also supplies hip joint
Nerve to vastus lateralis
Nerve to vastus intermedius
Nerve to vastus medialis
Saphenous nerve gradually crosses the femoral artery, gives branches, then supplies skin and periosteum over the tibia

Question 22

Describe the course of the anterior and posterior divisions of the obturator nerve, and what each supplies.

Answer 22

The posterior division supplies obturator externus, piercing the upper border then running deep to adductor brevis. A slender branch supplies the knee joint
The anterior division passes over obturator externus and emerging into the thigh supplies the hip joint, adductor brevis and longs and may help to supply pectineus