Anatomy 5 - Anatomy of Anaesthesia for Labour

Question 1

Which type of nerves supply structures in the pelvis?

Answer 1

Sympathetic
Parasympathetic
Visceral afferent
(body cavity)

Question 2

Which type of nerve supply structures in the perineum?

Answer 2

Somatic motor

Somatic sensory

Question 3

What type of nerves cause uterine cramping/ contraction?

Answer 3

Sympathetic/ parasympathetic (under hormonal influence)

Question 4

What type of nerves cause pelvic floor muscle contraction?

Answer 4

Somatic motor

Question 5

What type of nerves cause pain from the annexe (ovaries + fallopian tubes)?

Answer 5

Visceral afferents

Question 6

What type of nerves cause pain from the uterus?

Answer 6

Visceral afferents

Question 7

What type of nerves cause pain from the vagina?

Answer 7

Visceral afferents (pelvic part)
Somatic sensory (perineum)

Question 8

What type of nerves cause pain from the perineum?

Answer 8

Somatic sensory

Question 9

How do visceral afferent nerves from the superior aspect of pelvic organs (those touching the peritoneum) enter the spinal cord?

Answer 9

Run alongside the sympathetic fibres entering the spinal cord between levels T11-L2

Question 10

Where is pain from superior aspect of pelvic organs (those touching the peritoneum) felt by the patient?

Answer 10

Suprapubic

Question 11

How do visceral afferent nerves from the inferior aspect of pelvic organs (those not touching the peritoneum) enter the spinal cord?

Answer 11

Run alongside parasympathetic fibres entering the spinal cord at levels S2, 3, 4

Question 12

Where is pain from inferior aspect of pelvic organs (those not touching the peritoneum) felt by the patient?

Answer 12

Perineum (S2, 3, 4 dermatome)

Question 13

How do visceral afferent nerves from structures passing from pelvis to perineum located in the pelvis enter the spinal cord?

Answer 13

Run alongside the parasympathetic nerves and enter at levels S2, 3, 4

Question 14

How do somatic sensory nerves from structures crossing from pelvis to perineum in the perineum pass into the spinal cord?

Answer 14

Via pudendal nerve to spinal cord S2, S3, S4

Question 15

What are the 3 main types of anaesthesia used in pregnancy?

Answer 15

Spinal anaesthetic
Epidural anaesthetic
Pudendal nerve block

Question 16

What type of structures does a spinal block via lumbar puncture anaesthetise?

Answer 16

Intraperitoneal viscera
Subperitoneal viscera
Somatic structures

Question 17

What type of structures does a caudal epidural block anaesthetise?

Answer 17

Subperitoneal viscera

Somatic structures

Question 18

What type of structures does a pudendal nerve block anaesthetise?

Answer 18

Somatic structures

Question 19

At what vertebral level does the spinal cord become caudal equina?

Answer 19

L2 vertebra

Question 20

At what spinal cord level does the subarachnoid space end?

Answer 20

S2

Question 21

Between what spinal level is anaesthetic injected?

Answer 21

L3-L4 (L5) region

Question 22

What structures does a needle pass through when giving a spinal anaesthetic? (7)

Answer 22

Supraspinous ligament
interspinous ligament
ligamentum flavum
epidural space (fat and veins)
dura mater
arachnoid mater
finally reaches subarachnoid space (contains CSF)

Question 23

What structures does a needle pass through when giving an epidural anaesthetic? (4)

Answer 23

Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space (fat and veins)

Question 24

Which spinal nerves contain sympathetic fibres?

Answer 24

All (including named nerves e.g. femoral, sciatic, obturator, pudendal)

Question 25

What happens when giving a spinal anaesthetic due to the blockade of sympathetic ton e to all arterioles in the lower limb?

Answer 25

Vasodilation (skin looks flushed, warm lower limbs)
Reduced sweating
-> hypotension

Question 26

Nerve roots of pudendal nerve?

Answer 26

S2, S3, S4

Question 27

Nerve modalities of pudendal nerve?

Answer 27

Somatic motor

Somatic sensory

Question 28

Effect of pudendal nerve block?

Answer 28

Anaesthetises the majority of the perineum

Question 29

3 circumstances when pudendal nerve block may be used?

Answer 29

Episiotomy incision
Forceps use
Perineal stitching post delivery

Question 30

How does the pudendal nerve exit the pelvis?

Answer 30

Greater sciatic foramen

Question 31

Where does the pudendal nerve pass in relation to the sacrospinous ligament?

Answer 31

Posterior

Question 32

How does the pudendal nerve re-enter the pelvis/ perineum?

Answer 32

Via the lesser sciatic foramen

Question 33

What 4 structures pass within the pudendal canal?

Answer 33

Pudendal nerve
Internal pudendal artery and vein
Nerve to obtruator itnernus

Question 34

What is the pudendal canal a passageway through?

Answer 34

Obturator fascia

Question 35

What is used as a landmark of where to administer a pudendal nerve block?

Answer 35

Ischial spine