Lecture 18- Lumbrosacral plexus

Question 1

muscles lining the posterior abdominal wall (4)

Answer 1

psoas major
iliacus
quadratus lumborum
psoas minor- missing in 40% of population

Question 2

loose areolar connective tissue that lines the posterior abdominal wall muscles and the entire internal surface of the abdominal wall

Answer 2

endoabdominal (or transversalis) fascia

Question 3

endoabdominal (or transversalis) fascia is continuous with the ________ in the pelvis and is usually invested with fat.

Answer 3

endopelvic fascia

Question 4

where does the lumbar plexus form from?

Answer 4

anterior primary rami of L1-L4

T12 also contributes to the lumbar plexus

Question 5

roots that send white rami communicates to the sympathetic trunk

Answer 5

T12-L2

Question 6

where do the grey rami communicates enter?

Answer 6

all 5 roots, T12-L4

Question 7

the lumbar plexus forms within what muscle?

Answer 7

psoas major

Question 8

the lumbar plexus emerges where from the psoas major?

Answer 8

lateral, anterior, and medial borders

Question 9

Nerve that emerges from T12

Answer 9

subcostal nerve

Question 10

Nerves that emerge from L1

Answer 10

iliohypogastric nerve and Ilioinguinal nerve

Question 11

nerve that emerges from L1-L2

Answer 11

genitofemoral nerve

Question 12

nerve that emerges from L2-L3

Answer 12

lateral femoral cutaneous nerve

Question 13

nerves that emerge from L2-L4

Answer 13

femoral nerve, obturator nerve

Question 14

In about 9% of cases, this nerve exists

Answer 14

accessory obturator nerve

Question 15

What is the sacral plexus formed by?

Answer 15

• lumbosacral trunk

- ventral primary rami of S1-3 and part of S4

Question 16

Where does the sacral plexus lie?

Answer 16

anteriorly to the piriformis muscle on the posterior pelvic wall

Question 17

What is the sacral plexus covered by?

Answer 17

endopelvic fascia

Question 18

2 division of sacral plexus

Answer 18

anterior and posterior

Question 19

nerves in posterior division of sacral plexus

Answer 19

• superior gluteal nerve
• inferior gluteal nerve
• sciatic nerve (also anterior)
• posterior femoral cutaneous nerve
• perforating cutaneous nerve
• nerve to piriformis muscle

Question 20

nerves in anterior division of sacral plexus

Answer 20

• sciatic nerve (also posterior)
• nerve to quadratus femoris and gemellus inferior
• nerve to obturator internus and gemellus superior
• posterior femoral cutaneous nerve
• pudenal nerve
• pelvic splanchnic nerves
• sacral nerve
• nerve to levator ani

Question 21

superior gluteal nerve

Answer 21

• posterior division
• L4-5, S1
• innervates gluteus medius, gluteus minimus, and tensor fascia lata

Question 22

inferior gluteal nerve

Answer 22

• posterior division
• L5, S1-2
• innervates gluteus maximus

Question 23

sciatic nerve

Answer 23

• posterior and anterior divisions
• L4-S3
• innervates hamstring and muscles of leg and foot
• supplies sensory to skin on lateral aspect of leg and foot

Question 24

What nerves does the sciatic nerve split into?

Answer 24

• tibial nerve: L4-S3

- common peroneal nerve: L4-S2

Question 25

nerve to quadratus femoris and gemellus inferior

Answer 25

- anterior division - L4-S1 - innervates quadratus femori and gemellus inferior

Question 26

nerve to obturator internus and gemellus superior

Answer 26

- anterior division - L5-S2 - innervates obturator internus and gemellus superior

Question 27

posterior femoral cutaneous nerve

Answer 27

- anterior: S2-3 - posterior: S1-2 - sensory to thigh

Question 28

perforating cutaneous nerve

Answer 28

- posterior division - S2-3 - sensory to medial aspect of buttocks

Question 29

pudenal nerve

Answer 29

- anterior division - S2-S4 - innervates muscles of the perineum - provides sensory to lower half of anal canal, perianal skin, and genitalia in both sexes

Question 30

pelvic splanchnic nerves

Answer 30

- anterior division | - S2-perineal branch of S4

Question 31

nerve to levator ani

Answer 31

- anterior division | - S3-S4

Question 32

iliohypogastric nerve

Answer 32

- L1 - to gluteal and hypogastric skin - to external and internal abdominal oblique muscles and transversus abdominis

Question 33

ilioinguinal nerve

Answer 33

- L1 - to skin of groin and scrotum/labia majorum - to external and internal abdominal oblique muscles and transversus abdominis

Question 34

genitofemoral nerve

Answer 34

- L1-2 - to skin of mons pubis, labia majorum/scrotum - to skin of femoral triangle, cremaster muscle

Question 35

lateral femoral cutaneous nerve

Answer 35

- L2-3 | - supplies sensory to skin on anterolateral thigh

Question 36

femoral nerve

Answer 36

- L2-4 - to anterior surface of thigh and medial aspect of leg and foot - to skin on medial side of leg and foot via saphenous branch - innervates iliacus, pectineus, sartorius, quadriceps femoris - to articular capsule of hip and knee joints

Question 37

obturator nerve

Answer 37

- L2-4 - to medial surfaces of thigh and articular capsule of hip and knee joints - innervates gracilis, adductor brevis, adductor longus, adductor magnus, obturator externus - sometimes innervates pectineus via accessory obturator nerve (L3-4)