Lumbosacral plexus

Question 1

What is a rhizotomy?

Answer 1

Nerve roots can be selectively sectioned for relief of intractable pain or paralysis

Question 2

What does a spinal nerve divide into?

Answer 2

Posterior and anterior rami

Question 3

What is a mixed spinal nerve?

Answer 3

Posterior and anterior roots

Question 4

What kind of nerve is the anterior root?

Answer 4

Motor - going out of the plexus

Question 5

What kind of nerve is the posterior root?

Answer 5

Sensory - going in to the plexus

Question 6

What is a spinal nerve?

Answer 6

Arises as rootlets from anterior (ventral) and posterior (dorsal) horns of spinal grey matter

Question 7

Which spinal nerves form the lumbar plexus?

Answer 7

L1 to L4

Question 8

Which spinal nerves form the sacral plexus?

Answer 8

L4-S4

Question 9

What connects the lumbar and sacral plexuses?

Answer 9

Lumbosacral trunk

Question 10

What is the lumbar plexus composed of?

Answer 10

L1 to L4 anterior rami

Contribution from subcostal nerve T12

Question 11

Which spinal nerves innervate the femoral nerve?

Answer 11

L2-L4

Question 12

Which spinal nerves innervate the obturator nerve?

Answer 12

L2-L4

Question 13

Which spinal nerves innervate the lateral cutaneous nerve of the thigh?

Answer 13

L2-L3

Question 14

Which spinal nerves innervate the genitofemoral nerve?

Answer 14

L1-L2

Question 15

Which spinal nerves innervate the ilii-inguinal nerve?

Answer 15

L1

Question 16

Which spinal nerves innervate the Clio-hypogatric nerve?

Answer 16

L1

Question 17

Where is the genitofemoral nerve?

Answer 17

Anterior to psoas major

Question 18

Where is the obturator nerve?

Answer 18

Medial to psoas major

Question 19

Where are the femoral, lateral cutaneous, ilio-inguinal and ilio-hypogastric nerves?

Answer 19

Lateral to psoas major

Question 20

What does the femoral nerve do?

Answer 20

Innervate anterior compartment of thigh - flexes hip and extends knee

Question 21

What does the obturator nerve do?

Answer 21

Supplies medial (adductor) compartment of thigh - flexes hip and extends knee

Question 22

What is the lumbosacral trunk composed of?

Answer 22

Union of descending branch of L4 and anterior ramus of L5

Question 23

What is the sacral plexus formed from?

Answer 23

Anterior rami of S1 to S4 and lumbosacak trunk in posterolateral wall of lesser pelvis

Question 24

How are terminal nerves formed?

Answer 24

Anterior rami of L4 to S3 has ventral and dorsal divisions that combine with similar divisions from other levels

Question 25

Where do most branches of the sacral plexus leave the pelvis?

Answer 25

Greater sciatic foramen

Question 26

What is the reference muscle for the sacral plexus?

Answer 26

Piriformis muscle in lower pelvic cavity

Question 27

Which spinal nerves innervate the sciatic nerve?

Answer 27

L4 to S3

Question 28

Which spinal nerves innervate the superior gluteal nerve?

Answer 28

L4 to S1

Question 29

Which spinal nerves innervate. the inferior gluteal nerve?

Answer 29

L5 to S2

Question 30

Which spinal nerves innervate the pudendal nerve?

Answer 30

S2 to S4

Question 31

What does the sciatic nerve supply?

Answer 31

Posterior compartment of thigh and muscles of leg and foot

Question 32

Where is the superior gluteal nerve located?

Answer 32

Passes through greater sciatic foramen above piriformis muscle

Question 33

What does the superior gluteal nerve supply?

Answer 33

Gluteus medius and gluteus minimus

Question 34

Where is the inferior gluteal nerve located?

Answer 34

Passes through greater sciatic foramen below piriformis

Question 35

What does the inferior gluteal nerve supply?

Answer 35

Gluteus maximus

Question 36

What does the pudendal nerve supply?

Answer 36

Perineum and external genitalia

Question 37

What is the intervertebral foramen?

Answer 37

Opening between two vertebrae

Question 38

Characteristics of injury to lumbosacral plexus

Answer 38

Pain/weakness/loss of sensation of lower limb

Question 39

Symptoms of acute lumbosacral plexitis

Answer 39

Rapid onset of pain of thigh/hip

Question 40

Symptoms of sciatica

Answer 40

Pain of back/hip/outside leg

Question 41

What is sciatica?

Answer 41

Compression of spinal nerve root of sacral plexus due to degeneration of intervertebral disc or disc herniation

Question 42

Why does a mother feel pain in her lower limbs during child birth?

Answer 42

Fetal head compresses nerves of sacral plexus

Question 43

What is obturator nerve neurectomy?

Answer 43

Spasm of adductor muscles of thigh in spastic paraplegia can be relieved by dividing the obturator nerve

Question 44

What is piriformis syndrome?

Answer 44

Spasms of piriformis muscle and compression of sciatic nerve causing pain/numbness/tingling along leg and foot Sciatic nerve emerges inferior to piriformis

Question 45

Why is piriformis syndrome common in sports players?

Answer 45

They use gluteal muscles frequently, resulting in atrophy

Question 46

Where should you administer an intragluteal injection?

Answer 46

Superolateral quadrant or superior to the line expanding from the posterior superior iliac spine to the superior border of the greater trochanter

Question 47

Why is it dangerous to posteriorly dislocate the hip?

Answer 47

May injure the sciatic nerve | leading to paralysis

Question 48

What is foot drop caused by?

Answer 48

Injury to sciatic nerve

Question 49

Which areas of the leg are supplied by the saphenous branch of the femoral nerve?

Answer 49

Medial side of leg, medial malleolus and hallux

Question 50

What is a lumbosacral plexus block?

Answer 50

Anaesthesia to lumbar plexus, including anterolateral and medial thigh, knee and saphenous nerve below knee

Question 51

Which parts of the leg does a sciatic nerve block numb?

Answer 51

Below knee except from area supplied by saphenous nerve

Question 52

When will the superior gluteal nerve be injured?

Answer 52

Common after hip replacement

Question 53

Symptoms of injury to superior gluteal nerve

Answer 53

Weakness of gluteus medius/minimus leading to gluteal gait Weakness abduction in hip joint Positive Trendelenburg sign

Question 54

Why do you lean to one side when you injure your superior gluteal nerve?

Answer 54

- When standing on one foot, normally gluteus medius and minimus would contract to prevent pelvis tipping to unsupported side - If standing foot gluteus medius and minimus are weak, the pelvis tilts downwards on unsupported side - Individual tends to lean away from unsupported side to compensate for descend of pelvis - waddling