The Lumbosacral Plexus

Question 1

Remember that the aorta divides into the right & left common iliac arteries at ~ _____ vertebral column level

Answer 1

L4

Question 2

The common iliacs then descend along the pelvic brim and bifurcate into the ____ and ___

Answer 2

external & internal iliac arteries

Question 3

Each external iliac arteries eventually passes beneath the inguinal ligament and becomes the ____

Answer 3

femoral artery

Question 4

Each internal iliac artery then descends into the pelvic cavity along the lateral wall and branches into two main divisions:

Answer 4

1. Anterior division
2. Posterior division

Question 5

The anterior division of the internal iliac artery gives rise to branches that supply the

Answer 5

pelvic viscera (we will study these visceral branches in the Repro Block next fall), structures in the perineum (i.e., external genitalia), and the gluteal region

Question 6

While the posterior division of the internal iliac contributes branches that supply the _____, ____, ____ and ____

Answer 6

gluteal muscles/region, the lower back, and nearby sacral nerves and surrounding meninges (i.e. cauda equina)

Question 7

The posterior division of the internal iliac generally gives rise to three branches:

Answer 7

1. Iliolumbar
2. Lateral sacral
3. Superior gluteal

Question 8

The Lumbosacral plexus is formed by a collection of ventral/dorsal rami of the lumbar and sacral spinal nerves

Answer 8

ventral

Question 9

Lumbar Plexus- is formed by the ventral rami of spinal nerves ____ and the associated nerves which arise from these ventral rami

Answer 9

L1- L4

Question 10

____ formed by the ventral rami of L2 & L3- (courses beneath the inguinal ligament) supplies sensation to anterolateral thigh

Answer 10

Lateral Femoral Cutaneous Nerve

Question 11

_____ formed by ventral rami of L1 & L2 and gives rise to two branches:

1. Genital Branch- traverses the inguinal canal and innervates the scrotum/labia majora
2. Femoral Branch- supplies sensation to a small area on the proximal/anterior thigh

Answer 11

Genitofemoral nerve

Question 12

Two major nerves arise from the ventral rami of L2, L3 & L4:

Answer 12

1. Femoral Nerve- passes beneath the inguinal ligament and innervates the anterior thigh muscles (i.e. quadriceps and others)
2. Obturator Nerve- passes through the “obturator canal” and innervates the medial thigh muscles (adductors)

Question 13

Sacral Plexus- is formed by the ventral rami of ____ and the associated nerves which arise from these ventral rami

Answer 13

L4, L5 & S1- S4

Question 14

Answer 14

Question 15

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Question 16

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Question 17

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Question 18

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Question 19

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Question 20

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Question 21

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Question 22

Answer 22