LUMBAR PLEXUS

Question 1

• a sensorimotor nerve; cutaneous supply only in the lower limb
• branch of T-12 that supplies the superior anterolateral aspect of the thigh
• not usually considered part of the lumbar plexus

Answer 1

Subcostal Nerve

Question 2

• a sensorimotor nerve; cutaneous supply only in the lower limb
• from the ventral division of L-1 (may have a contribution from T-12)
• pierces the psoas major muscle near the kidney and passes within the abdominal wall, inferior to the subcostal nerve, to reach the posterolateral gluteal skin (near the iliac crest, posteriorly)

Answer 2

Iliohypogastric Nerve

Question 3

• a sensorimotor nerve; cutaneous supply only in the lower limb
• from the ventral division of L-1 (may have a contribution from T-12)
• follows a course similar to the iliohypogastric nerve, but continues anteriorly (along the inguinal ligament and through the inguinal canal) to reach the skin of the superior medial thigh

Answer 3

Ilioinguinal Nerve

Question 4

• a sensorimotor nerve; cutaneous supply only in the lower limb
• from the ventral divisions of L-1 & L-2
• pierces the psoas major muscle anteriorly and enters the thigh dorsal to the inguinal ligament, near its center

Answer 4

Genitofemoral Nerve

Question 5

-passes medially, along the inguinal ligament to supply part of the external genitalia

Answer 5

Genital Branch

Question 6

• passes deep to the inguinal ligament with the femoral a. through the vascular lacuna to supply the skin of the anterior superior thigh
• may aid or replace the intermediate femoral cutaneous nerve

Answer 6

Femoral Branch

Question 7

-a sensory nerve; cutaneous supply only in the lower limb
-from the dorsal divisions of L-2 & L-3
-pierces the psoas major muscle laterally and courses along the iliac fossa
anterior to the iliacus muscle to enter the thigh anterolaterally, near the
attachment of the inguinal ligament on the anterior superior iliac spine, and
then supplies the anterolateral aspect of the thigh
-the n. usually passes deep to the inguinal ligament, but may pass through it

Answer 7

Lateral Femoral Cutaneous Nerve

Question 8

• from the dorsal divisions of L-1 through L-3
• these branches usually pass directly into the psoas major muscle belly, without uniting, to supply motor innervation to the muscle
• these branches do not exit the pelvis
• are not branches of the femoral nerve

Answer 8

nerves to psoas major muscle

Question 9

• a sensorimotor nerve; from the dorsal divisions of L-2 through L-4
• passes inferiorly intermediate to the psoas major and iliacus muscles, enters the thigh by passing through the muscular lacuna deep to the inguinal ligament near its midpoint to provide muscular branches to the thigh, articular branches to the hip and knee joints and gives rise to the following cutaneous nerve branches:
• a small branch, dorsal divisions of L-2 through L-4, passes directly to the iliacus muscle without exiting the pelvis to provide it with motor innervation

Answer 9

Femoral Nerve

Question 10

• dorsal divisions L-2 and L-3

- supplies a long, thin area of the anterior aspect of the thigh

Answer 10

Intermediate Femoral Cutaneous Nerve(s)

Question 11

• dorsal divisions L-2 and L-3

- supplies a long, thin area of the anteromedial aspect of the thigh

Answer 11

Medial Femoral Cutaneous Nerve(s)

Question 12

• dorsal divisions L-3 and L-4

- supplies the medial 1/2 of the leg

Answer 12

Saphenous Nerve

Question 13

-a sensorimotor nerve; from the ventral divisions of L-2 through L-4
-pierces the psoas major muscle medially near the linea terminalis, passes
anteroinferiorly into the lesser pelvis and passes through the obturator canal
to provide muscular branches to the thigh, articular branches to the hip and knee joints, and the cutaneous branch to the small area of the medial aspect of
the thigh

Answer 13

Obturator Nerve

Question 14

• a sensorimotor nerve; from the ventral divisions of L-3 & L-4
• present in 8% of population - its course parallels the obturator nerve and, when present it provides muscular supply to pectineus muscle, an articular branch to the hip joint and joins the obturator nerve’s cutaneous supply to the thigh

Answer 14

Accessory Obturator Nerve

Question 15

-part of the ventral ramus of L-4 and the entire ventral ramus of L-5 unite to form a large nerve which crosses the sacroiliac joint anteriorly at the pelvic brim and joins the sacral plexus

Answer 15

Lumbosacral Trunk