1: Anatomy - Anaesthesia of labour

Question 1

Where is visceral pain felt when organs are affected in

a) the superior pelvis
b) the inferior pelvis?

Answer 1

a) Suprapubic region

b) S2,3,4 region (bullseye around the anus i.e the perineum)

Question 2

What colour is the ligamentum flavum?

Why?

Answer 2

Yellow

Contains elastin

Question 3

What are the main symptoms of raised intracranial pressure?

Answer 3

Headache

Visual changes

Question 4

The uterine contractions of menstruation and childbirth are controlled by ___ which trigger which type of nerve?

Answer 4

hormones

autonomic nerves (sympathetic and parasympathetic, or ‘visceral motor’)

Question 5

Which modality of nerve controls the pelvic floor muscles?

Answer 5

Somatic motor

Question 6

Which sensory modality supplies organs

a) above the pelvic pain line
b) below the pelvic pain line
c) in the perineum?

Answer 6

a) Visceral afferent

b) Visceral afferent

c) Somatic sensory

Question 7

Which organs are above the pelvic pain line?

Answer 7

Those which touch the parietal peritoneum

So the bladder, ovaries and uterine tubes, uterus, superior vagina

Question 8

Which organs are below the pelvic pain line?

Answer 8

Those which are above the levator ani muscle but don’t touch the parietal peritoneum

Cervix, inferior vagina

Question 9

Which named nerve supplies somatic sensory fibres to structures in the perineum?

Answer 9

Pudendal nerve (S2,3,4)

Question 10

Which nerve roots supply sensory fibres to structures

a) above the pelvic pain line
b) below the pelvic pain line
c) in the perineum?

Answer 10

a) T11 - L2

b) S2-4

c) S2-4

Question 11

Are organs below the pelvic pain line all supplied by the pudendal nerve?

Answer 11

No - VISCERAL AFFERENTS from S2,3,4 (I appreciate this is confusing)

Structures in the perineum are supplied with somatic sensory fibres by the pudendal nerve (S2,3,4)

Question 12

How do

a) visceral afferents from above the pelvic pain line
b) visceral afferents from below the pelvic pain line
c) somatic sensory fibres from the perineum

plug into the spinal cord, and at which levels?

Answer 12

a) Travel with sympathetics back to T11-L2 within periarterial plexuses
b) Travel with parasympathetics back to S2-4 within pelvic splanchnic nerves
c) Travel back to S2-4 within the pudendal nerve

Question 13

What are the two important sets of spinal cord levels for the female reproductive system?

Answer 13

T11 - L2 (visceral afferents ABOVE pelvic pain line)

S2 - S4 (visceral afferents BELOW pelvic pain line; perineum)

Question 14

What are three kinds of anaesthesia which can be given to pregnant women?

Answer 14

Spinal anaesthesia

Epidural anaesthesia

Pudendal nerve block

Question 15

Where are spinal and epidural anaesthetics injected?

Answer 15

L3/4 or L4/5

Just like a lumbar puncture

Remember L2 is the termination of the spinal cord

Question 16

What is the difference between a spinal and epidural anaesthetic?

Answer 16

Spinal anaesthetic injected through all layers into SUBARACHNOID SPACE

Epidural anaesthetic injected into EPIDURAL SPACE - fewer layers breached

Question 17

From superficial to deep, name the layers a needle passes through when giving spinal anaesthesia.

Answer 17

Skin

Fascia

Supraspinous lig.

Interspinous lig.

Ligamentum flavum

Epidural space

Dura

Arachnoid

Subarachnoid space!

Question 18

From superficial to deep, name the layers a needle passes through when giving epidural anaesthesia.

Answer 18

Skin

Fascia

Supraspinous lig.

Infraspinous lig.

Ligamentum flavum

Epidural space!

Question 19

At what levels can

a) spinal
b) epidural anaesthesia be given?

Answer 19

Both are L3/4 or L4/5

Same as a lumbar puncture

Question 20

What are the risks involved in giving spinal anaesthesia?

Answer 20

Raised ICP - increased volume in subarachnoid space

Hypotension - widespread vasodilation due to anaesthetic’s effect on sympathetics

Also: nerve damage, haemorrhage, infection

Question 21

What structures are numbed by a spinal anaesthetic?

Answer 21

Intraperitoneal structures and everything below the waist - above PPL, below PPL, perineum, lower limbs

Question 22

What structures are numbed by an epidural anaesthetic?

Answer 22

Structures above and below PPL + perineum

Question 23

Can an epidural anaesthetic cause

a) raised intracranial pressure
b) hypotension?

Answer 23

a) No - doesn’t penetrate subarachnoid space

b) Yes - same effect on sympathetic nerves

Question 24

Why can spinal and epidural anaesthetics cause hypotension?

Answer 24

All spinal nerves contain sympathetics

Sympathetics control arteriolar vasoconstriction (sympathetic tone)

Sympathetics blocked - widespread vasodilation, hypotension

Question 25

Which **branch of the sacral plexus** has roles in the GI, renal and female reproductive systems?

Answer 25

**Pudendal nerve** (S2,3,4)

Question 26

Which **nerve** supplies **somatic sensory fibres** to the **external anal and urethral sphincters?**

Answer 26

**Pudendal nerve**

Question 27

Which type of **anaesthesia** numbs the **perineum only**?

Answer 27

**Pudendal nerve block**

Question 28

Which type of anaesthesia would be given to a woman undergoing an episiotomy?

Answer 28

**Pudendal nerve block**

Question 29

Where does the **pudendal nerve** EXIT the pelvis?

Answer 29

**Greater sciatic foramen**

Question 30

Where does the **pudendal nerve** RE-ENTER the pelvis?

Answer 30

**Lesser sciatic foramen**

Question 31

Which pelvic structure does the **pudendal nerve** pass **POSTERIOR** to?

Answer 31

**Sacrospinous ligament**

Question 32

Which **passageway**, found within the pelvis, does the **pudendal nerve** travel within?

Answer 32

**Pudendal canal**

Question 33

Which **fossa** is the pudendal canal found in?

Answer 33

**Ischioanal fossa**

Question 34

Which **fascia** is the **pudendal canal found in?**

Answer 34

**Obturator fascia**

Question 35

What are the **contents** of the **pudendal canal**?

Answer 35

**Pudendal nerve** **Internal pudendal artery** **Internal pudendal vein** **Nerve to obturator internus**

Question 36

Which **muscle** is in close relation to the **obturator canal**?

Answer 36

**Obturator internus**

Question 37

The **pudendal canal** is found in the ___ **fossa**, within the ___ **fascia**. It contains the ___ **nerve** and ___ \_\_\_ **artery and vein**. It is bounded by the muscle called ___ \_\_\_.

Answer 37

**ischioanal fossa** **obturator fascia** **pudendal nerve** **internal pudendal artery and vein** **obturator internus**

Question 38

The **pudendal nerve** supplies which area with **somatic sensory** fibres?

Answer 38

**Perineum**

Question 39

Which **bony landmark** is used in **pudendal nerve block?** ## Footnote **Why?**

Answer 39

**Ischial spine** Palpated with one hand in vagina and anaesthetic injected at fingertips **Pudendal nerve travels closely with sacrospinous ligament**

Question 40

What is **pudendal nerve block** used for?

Answer 40

**Episiotomy** **Repair of tears** **Forceps delivery**

Question 41

What can happen to the **pudendal nerve** during childbirth?

Answer 41

**Stretching** \> **Nerve damage**

Question 42

Which **specific muscles** can be damaged during childbirth?

Answer 42

**Puborectalis** (part of levator ani group) ## Footnote **External anal sphincter**

Question 43

What is an **episiotomy**?

Answer 43

**Incision made below posterior fourchette to prevent spontaneous tearing during childbirth**

Question 44

In which **direction** is an **episiotomy** usually made?

Answer 44

**Inferolaterally**

Question 45

**Median** (vertical) **episiotomy** isn't commonly done. Why not?

Answer 45

**Potential to damage PERINEAL BODY** - mass acting as insertion for loads of pelvic floor muscles AND **Further tearing in that direction will involve the external anal sphincter**

Question 46

What is the **bony landmark** for **L4?**

Answer 46

**Posterior iliac crests**