Anatomy of Anaesthesia for Labour

Question 1

What is above and below the levator ani muscle?

Answer 1

Above = pelvis
Below = perineum

Question 2

nerve type in Uterine ‘cramping’

Answer 2

e.g. menstruation

Hormonal (sympathetic/parasympathetic)

Question 3

nerve type in uterine contraction

Answer 3

e.g. during labour

Hormonal (sympathetic/parasympathetic)

Question 4

nerve type in pelvic floor muscle contraction

Answer 4

e.g. during a sneeze

Somatic motor

Question 5

nerve type in pain from adnexae (ovaries + fallopian tubes)

Answer 5

visceral afferents

Question 6

nerve type in pain from uterus

Answer 6

visceral afferents

Question 7

nerve type in pain from vagina

Answer 7

visceral afferents (upper)
Somatic sensory (lower)

Question 8

nerve type in pain from perineum

Answer 8

somatic sensory

Question 9

pain sensation in superior pelvic organs / touching peritoneum

Answer 9

‘Suprapubic’ pain
Visceral afferents, runs along side sympathetic fibres
enters spinal cord between levels T11-L2

Question 10

Pain sensation in inferior aspect of pelvic organs/ no touching peritoneum

Answer 10

Perineum pain (dermatomes S2,3,4)
Visceral afferents, runs alongside parasympathetic fibres
Enters spinal cord at levels S2,3,4

Question 11

spinal + epidural anaesthetic level

Answer 11

L3-L4 (anaesthetises the cauda equina [starts at L2])

Question 12

spinal anaesthetic injected into …

Answer 12

subarachnoid space (contains CSF)

Question 13

epidural anaesthetic injected into …

Answer 13

epidural space (fat and veins)

Question 14

sympathetic outflow =

Answer 14

T1-L2
(below L2 level sympathetic ganglia receive fibres from L2 level via sympathetic chain and distribute via connections with lumbar, sacral and coccygeal spinal nerves)

Question 15

blocking sympathetic outflow causes …

Answer 15

vasodilation (hypotension, sign that anaesthetic is working)

Question 16

pudendal nerve route

Answer 16

exits pelvis via greater sciatic foramen
passes posterior to sacrospinous ligament
re-enters pelvis at lesser sciatic foramen

Question 17

landmark used to administer pudendal nerve block

Answer 17

ischial spine

Question 18

damage to pudendal nerve in delivery caused by..

Answer 18

torn fibres in levator ani or external anal sphincter

Question 19

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

Answer 19

Episiotomy (prevents incision going into rectum)