Anatomy of Anaesthesia for Labour

Question 1

List nerves associated with the perineum

Answer 1

BODY WALL
Somatic motor
Somatic sensory

Question 2

List nerves associated with the pelvis

Answer 2

BODY CAVITY
Sympathetic
Parasympathetic
Visceral afferent

Question 3

Which nerve structures transmit pain from the pelvis?

Answer 3

Visceral afferents - sympathetic or parasympathetic

Question 4

Which nerve structures transmit pain from the perineum?

Answer 4

Pudenal nerve - somatic sensory

Question 5

Where do visceral afferents enter the spinal cord for pelvic organs that TOUCH THE PERITONEUM? Where is pain perceived? List these organs

Answer 5

T11-L2 via sympathetic fibres
Suprapubic region
Uterine tubes, uterus, ovaries

Question 6

Where do visceral afferents enter the spinal cord for pelvic organs that are not touching the peritoneum (ABOVE LEVATOR ANI)? Where is pain perceived? List these organs

Answer 6

S2-S4 via parasympathetic fibres
S2,3,4 dermatome
Cervix and superior vagina

Question 7

Where does the pudenal nerve enter the spinal cord for structures in the perineum (BELOW LEVATOR ANI)? Where is pain perceived? List these organs

Answer 7

S2-S4 via somatic sensory fibres
Localised pain in perineum
Inferior vagina, perineal muscles, glands, skin

Question 8

Structures above levator ani are supplied by which nerve fibres?

Answer 8

IN PELVIS

Visceral afferents

Question 9

Structures below levator ani are supplied by which nerve fibres?

Answer 9

IN PERINEUM

Pudenal nerve

Question 10

What type of anaesthesia targets intraperitoneal, subperitoneal and somatic structures?

Answer 10

Spinal anaesthetic

Question 11

What type of anaesthesia targets subperitoneal and somatic structures?

Answer 11

Epidural anaesthetic

Question 12

What type of anaesthesia targets somatic structures only?

Answer 12

Pudenal nerve block

Question 13

Spinal cord becomes cauda equina at what vertebral level?

Answer 13

L2 vertebra

Question 14

SAS ends at which vertebral level?

Answer 14

S2

Question 15

Anaesthesia is injected into which vertebral region?

Answer 15

L3-L4 to anaesthetise cauda equina

Question 16

What is the surface landmark for injecting anaesthesia?

Answer 16

L4 spinous process

Superior point on iliac crests

Question 17

Describe the layers a needle passes through for spinal anaesthetic

Answer 17

Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
Dura matter
Arachnoid matter
SAS with CSF

Question 18

Describe the layers a needle passes through for epidural anaesthetic

Answer 18

Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space

Question 19

What is the distinguishing feature of ligamentum flavum?

Answer 19

Yellow as it is elastic

Question 20

Describe sympathetic outflow below L2 vertebra

Answer 20

Sympathetic ganglia receive fibres from L2 via sympathetic chain
Distribute to lumbar, sacral, coccygeal spinal nerves

Question 21

All spinal nerves and named nerves contain sympathetic fibres. True/ False?

Answer 21

True

Question 22

What do sympathetic fibres supply, creating sympathetic tone? Blockage of sympathetic tone causes…

Answer 22

All arterioles

Vasodilatation

Question 23

List signs that spinal anaesthetic is working

Answer 23

Flushed lower limbs
Warm lower limbs
Reduced sweating

Question 24

The pudenal nerve supplies all of the perineum. True/False?

Answer 24

False

Supplies most of it - also supplied by ilioinguinal nerve

Question 25

Outline the route taken by the pudenal nerve to structures of the perineum

Answer 25

Exits pelvis via greater sciatic foramen --> Passes posterior to sacrospinous ligament --> Reenters pelvis/ perineum via lesser sciatic foramen --> Travels in pudenal canal --> Branches supply perineum

Question 26

What is the pudenal canal?

Answer 26

Passage in obturator fascia containing internal pudenal artery and vein, pudenal nerve and nerve to obturator internus

Question 27

Which bony landmark is used in the administration of pudenal nerve block?

Answer 27

Ischial spine

Question 28

List instances in which a pudenal nerve block can be applied

Answer 28

Labour Forceps delivery Vaginal delivery Epiostomy

Question 29

During labour, branches of which nerve can be torn?

Answer 29

Pudenal nerve (supplying levator ani and external anal sphincter)

Question 30

Which component of the levator ani is typically torn fist during labour?

Answer 30

Puborectalis

Question 31

How is tearing in the perineum during childbirth described?

Answer 31

First degree Second degree Third degree

Question 32

What is the clinical significance of damage to dtructures due to perineal tearing?

Answer 32

Weakened pelvic floor | Faecal incontinence

Question 33

What is an 'epiostomy'

Answer 33

A surgical cut made at the opening of the vagina during childbirth, to aid a difficult delivery and prevent rupture of tissues

Question 34

List types of epiostomy incision

Answer 34

Posterolateral | Median

Question 35

A posterolateral epiostomy incision is made into which anatomical structure?

Answer 35

Ischioanal fossae

Question 36

A median incision is not used as often as it can damage which structure?

Answer 36

External anal sphincter if further tearing occurs posteriorly

Question 37

The pudenal canal passes on the surface of which muscle?

Answer 37

Obturator internus