Lumbar Plexus Flashcards Preview

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Flashcards in Lumbar Plexus Deck (46):
1

What is the lumbar plexus?

A network of nerve fibres that supplies the skin and musculature of the lower limb

2

Where is the lumbar plexus located?

Within the substance of the psoas major muscle, and the anterior of the transverse processes of the lumbar vertebrae

3

What is the lumbar plexus formed by?

The anterior rami (divisions) of the lumbar spinal nerves, L1, L2, L3  and L4

4

What does the lumbar plexus receive contributions from?

The thoracic spinal nerve 12

5

What happens at each vertebral level?

Paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column

6

What happens once spinal nerves have left the vertebral column?

Each nerve divides into anterior and posterior nerve fibres

7

How does the lumbar plexus begin?

As the anterior fibres of the spinal nerves L1-L4

8

What happens to the anterior rami of the L1-4 spinal roots?

They divide into several cords, which then combine together to form the six major peripheral nerves of the lumbar plexus

9

What happens to the six major peripheral nerves of the lumbar plexus?

They descend down the posterior abdominal wall to reach the lower limb, where they innervate their target structures

10

What are the 6 major peripheral nerves of the lumbar plexus?

Iliohypogastric nerve
Ilioinguinal nerve
Genitofemoral nerve 
Lateral cutaneous nerve of the thigh 
Obturator nerve
Femoral nerve

11

Where does the iliohypogastic nerve run?

To the iliac crest, across the quadratus lumborum muscle of the posterior abdominal wall

12

Where does the iliohypogastric nerve perforate?

The transversus abdominis

13

What are the roots of the iliohypogastric nerve?

L1 (with contributions from T12)

14

What muscles does the iliohypogastric nerve innervate?

Internal oblique 
Transversus abdominis

15

What is the sensory function of the iliohypogastric nerve?

Innervates posterolateral gluteal skin in the pubic region

16

What course does the ilioinguinal nerve follow?

The same as the iliohypogastric

17

Where does the ilioguinal nerve pass through?

After innervating the muscles of the anterior abdominal wall, it passes through the superficial inguinal ring

18

What is the root of the ilioguinal nerve?

L1

19

What muscles does the ilioinguinal nerve innervate?

Internal oblique 
Transversus abdominis

20

What are the sensory functions of the ilioinguinal nerve?

Innervates the skin on the upper middle thigh 
In males, it also supples the skin over the root of the penis and anterior scrotum 
In females, it supplies the skin over the mons pubis and labium majus

21

What happens to the genitofemoral nerve after leaving the psoas major muscle?

It quickly divides into a genital branch, and a femoral branch

22

What are the roots of the genitofemoral nerve?

L1, L2

23

What muscles does the genitofemoral nerve innervate?

The genital branch innervates the cremasteric muscle

24

What are the sensory functions of the genitofemoral nerve?

The genital branch innervates the skin of the anterior scrotum (in males), or the skin over mons pubis and labium majus (in females). 
The femoral branch innervates the skin on the upper anterior thigh

25

Where does the lateral cutaneous nerve of the thigh enter the thigh?

At the lateral aspect of the inguinal ligament

26

What are the roots of the lateral cutaneous nerve of the thigh?

L2, L3

27

What muscles are innervated by the lateral cutaneous nerve of the thigh?

None- it has a purely sensory function

28

What are the sensory functions of the lateral cutaneous nerve of the thigh

Innervates anterior and lateral thigh down to the level of the knee

29

What are the roots of the obturator nerve?

L2, L3, L4

30

What muscles does the obturator nerve innervate?

Obturator externus 
Pectineus 
Adductor longus 
Adductor brevis
Adductor magnus 
Gracilis

31

What are the sensory functions of the obturator nerve?

Innervates the skin over the medial thigh

32

What are the roots of the femoral nerve?

L2, L3, L4

33

What muscles does the femoral nerve innervate?

Illiacus 
Pectineus 
Sartorius 
All muscles of quadriceps femoris

34

What is the sensory function of the femoral nerve?

Innervates the skin on the anterior thigh and medial leg

35

What is a lumbosacral plexopathy?

A disorder affecting either the lumbar or sacral plexus of nerves

36

How common are lumbosacral plexopathies?

Rare

37

What causes a lumbosacral plexopathy?

Damage to the nerve bundles

38

When is a plexopathy suspected?

If the symptoms cannot be localised to a single nerve

39

What may a patient complain of when they have a plexopathy?

Neuropathic pains 
Numbness
Weakness
Wasting of muscles

40

Give 3 causes of lumbosacral plexopathy

Diabetic amyotrophy 
Idiopathic pleoxopathy
Tumours and other local invasions

41

What happens in diabetic amyotrophy?

High blood sugar levels damage the nerves

42

What is idiopathic plexopathy the lumbosacral equivalent of?

Parsonage-Turner syndrome (which affects the brachial plexus)

43

How can tumours and other local invasions can plexopathy?

Due to compression of the plexus

44

What does treatment of a plexopathy depend on?

What is causing the symptoms

45

How is a lumbosacral plexopathy treated when its caused by tumours and space occupying lesions?

They should be removed if possible

46

How is a lumbosacral plexopathy treated when it has a diabetic or idiopathic cause?

High-dose corticosteroids