Sacral Plexus Flashcards Preview

â–ș Med Misc 25 > Sacral Plexus > Flashcards

Flashcards in Sacral Plexus Deck (40):
1

What is the sacral plexus?

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

2

Where is the sacral plexus located?

On the surface of the posterior pelvic wall, anterior to the piriformis muscle

3

What is the sacral plexus formed by?

The anterior rami (divisons) of the sacral spinal nerves S1, S2, S3, and S4. 
It also receives contributions from the lumbar spinal nerves L4 and L5

4

Where does the sacral plexus begin?

As the anterior fibres of S1, S2, S3, and S4

5

What forms the lumbosacral trunk?

The 4th and 5th lumbar roots

6

What happens to the lumbosacral trunk?

It descends into the pelvis, to meet the sacral roots as they emerge from the spinal cord

7

What happens to the anterior rami of the S1-S4 spinal roots and the lumbosacral trunk?

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

8

Where do the give major peripheral nerves of the sacral plexus travel?

They descent down the posterior pelvic wall, and then either-
Leave the pelvis via the greater sciatic foramen
Remain in the pelvis

9

What happens to the nerves that leave the pelvis via the greater sciatic foramen?

They enter the gluteal region of the lower limb, innervating the structures there

10

What happens to the nerves that remain in the pelvis?

They innervate the pelvic muscles, organs and perineum

11

What are the five major peripheral nerves of the brachial plexus?

Superior gluteal nerve
Inferior gluteal nerve
Sciatic nerve
Posterior femoral cutaneous 
Pudendal

12

What course does the superior gluteal nerve take?

It leaves the pelvis via the greater sciatic foramen, entering the gluteal region superiorly to the piriformis muscle

13

What is the superior gluteal muscle accompanied by for much of its course?

The superior gluteal artery and vein

14

What are the roots of the superior gluteal nerve?

L4, L5, S1

15

What muscles does the superior gluteal nerve innervate?

Gluteus minimis 
Gluteus medius 
Tensor fascia latae

16

What are the sensory functions of the superior gluteal nerve?

None

17

What course does the inferior gluteal nerve take?

It leaves the pelvis via the greaer sciatic foramen, entering the gluteal region inferiorly to the piriformis muscle

18

What is the inferior gluteal nerve accompanied by for much of its course?

The inferior gluteal artery and vein

19

What are the roots of the inferior gluteal nerve?

L5, S1, S2

20

What muscle does the inferior gluteal nerve innervate?

Gluteus maximus

21

What is the sensory function of the inferior gluteal nerve?

None

22

What are the roots of the sciatic nerve?

L4, L5, S1, S2, S3

23

What are the parts of the sciatic nerve?

Tibial portion 
Common fibular portion

24

What muscles does the tibial portion of the sciatic nerve innervate?

All muscles of posterior compartment of thigh, including the hamstring portion of the adductor magnus, apart from the short head of the biceps femoris 
All muscles in the posterior compartment of the leg 
All muscles in sole of foot

25

What muscles does the common fibular portion of the sciatic nerve innervate?

Short head of biceps femoris 
All muscles of anterior and lateral compartments of the leg 
Extensor digitorum brevis

26

What are the sensory functions of the tibial portion of the sciatic nerve?

Innervates the skin on the posterolateral and medial surfaces of the foot, as well as the sole of the foot

27

What are the sensory functions of the common fibular portion of the sciatic nerve?

Innervates the skin on the anterolateral surface of the leg and the dorsal aspect of the foot

28

What course does the posterior femoral cutaneous nerve take?

It leaves the pelvis via the greater sciatic foramen, entering the gluteal region inferiorly to the piriformis muscle. It descends deep to the gluteus maximus, and runs down the back of the thigh to the knee

29

What are the roots of the posterior femoral cutaneous nerve?

S1, S2, S3

30

What muscles does the posterior femoral cutaneous nerve innervate?

None

31

What is the sensory function of the posterior femoral cutaneous?

Innervates the skin on the posterior surface of the thigh and leg 
Innervates skin of perineum

32

What course does the pudendal nerve take?

The nerve leaves the pelvis via the greater sciatic foramen, then re-enters via the lesser sciatic foramen. It moves anterosuperiorly along the lateral wall of the ischiorectal fossa

33

How does the pudendal nerve terminate?

By dividing into several branches

34

What are the roots of the pudendal nerve?

S2, S3, S4

35

What are the motor functions of the pudendal nerve?

Innervates skeletal muscles in the perineum, the external urethral sphincter, the external sphincter, levator ani

36

What is the sensory function of the pudendal nerve?

Innervates the penis and clitoris, and most of the skin of the perineum

37

What is found in addition to the five major nerves of the sacral plexus?

A number of smaller branches

38

What do the smaller branches coming from the sacral plexus tend to be?

Nerves that directly supply muscles

39

What is the exception to the smaller branches of the sacral plexus directly supplying muscles?

The perforating cutaneous nerve, which supplies the skin over the inferior gluteal region
The pelvic splanchnic nerves, which innervate the abdominal viscera

40

What are the important smaller branches of the sacral plexus?

Nerve to piriform 
Nerve to obturator internus 
Nerve to quadrator femoris