Anatomy of the Anaesthesia of Labour

Question 1

What type of nerve fibres will supply structures in the pelvic cavity?

Answer 1

Sympathetic or parasympathetic

Visceral afferents

Question 2

What type of nerve fibres will supply structures in the perineum?

Answer 2

Somatic motor

Somatic sensory

Question 3

How can we tell what is the pelvis and what is the perineum

Answer 3

Above levator ani= pelvis

Below= perineum

Question 4

What type of nerve fibres will sense pain in the superior aspect of the pelvic organs ie the part touching the peritoneum

Answer 4

Visceral afferent

Question 5

How do visceral afferents enter the spinal cord and at what level do they enter

Answer 5

travel alongside sympathetic nerve fibres

T11-L2

Question 6

How is pain in the superior aspect of the pelvic organs perceived by the patient

Answer 6

Suprapubic

Question 7

What type of nerve fibres sense pain in the inferior aspect of the pelvic organs

Answer 7

visceral afferents

Question 8

How do nerve fibres sensing pain in the inferior aspect of the pelvic organs get to the spinal cord and at what level do they enter

Answer 8

alongside parasympathetics

enter at S2, 3 and 4

Question 9

WHere is pain perceive from the inferor aspect of pelvic orgaisn

Answer 9

S2,3 and 4 dermatome

Question 10

What type of nerve fibres innervate structures what pass throught the perineum eg vagina, urethra

Answer 10

ABOVE (pelvis)- visceral afferents, parasympathetic, spinal cord levels S2, 3, 4
BELOW (perineum)- somatic sensory, pudendal nerve, S2, 3, 4

Question 11

At what point does the spinal cord become the cauda equina

Answer 11

L2 vertebrae

Question 12

Where does the subarachnoid space end

Answer 12

S2

Question 13

Where is anaesthesia injected to in a spinal and epidural anaestetic

Answer 13

L3-L5 region

Question 14

Name the levels that the needle will pass through when giving a spinal anaesthetic

Answer 14

Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural Space
Dura mater
Arachnoid mater
The it reaches the subarachnoid space

Question 15

What is the difference between an epidural and a spinal anaesthetic

Answer 15

• Epidural injected into epidural space but spinal goes into subarachnoid space
• epidural can be used anywhere in spinal cord, spinal cannot

Question 16

What is a caudal epidural

Answer 16

anaesthetic inject through sacral hiatus (instead of L3/4)

Question 17

what is a 1st degree tear

Answer 17

skin

not usually stitched up

Question 18

2nd degree

Answer 18

skin
peritoneal muscle
usually stitched up

Question 19

3rd degree

Answer 19

skin
peritoneal muscle
anal sphincter
needs stitched up

Question 20

4th degree

Answer 20

skin
peritoneal muscle
anal sphincter
rectum

Question 21

Where do sympathetic nerves exit the spinal cord?

Answer 21

T1-L2

Question 22

What signs in the lower limbs may indicate that spinal anaestetic is working and why

Answer 22

skin is flushed
warm
reduced sweating

blockade of sympathetic tone causes vasodilation

Question 23

What type of nerve fibres is the pudendal nerv

Answer 23

somatic motor and somatic sensory to the perineum

Question 24

What are the roots of the pudendal nerve

Answer 24

S2, 3, 4

Question 25

When may a pudendal nerve block be used

Answer 25

episiotomy
forceps
perineal stitching post delivery

Question 26

Describe the pathway of the pudendal nerve

Answer 26

• exits the pelvis via the greater sciatic foramen
• passes posterior to sacrospinous ligament
• re-enters pelvis/perineum via lesser sciatic foramen
• travels in pudendal canal

Question 27

What is the pudendal canal

Answer 27

passageway withing the obturator fascia

with internal pudendal artery and vein (and nerve to obturator internus)

Question 28

How does the clinician know where to inject the anaesthesia in pudendal nervw block

Answer 28

Pudendal nerve crosses the latera aspect of sacrospinal ligament
-ischial spine can be used as a landmark to administer blocj

Question 29

What can result from damage to the pudendal nerve/levator ani or externa anal sphincter during labout

Answer 29

weak pelvic foor

faecal incontinence

Question 30

What is a episiotomy

Answer 30

posterolateral (mediolateral incision) made into the ischioanal fossa to avoid incision or tearing into the rectum during labour
Median incisions used less often as tearing of these further will restul in damage to the anal sphincter