Anatomy of Anaesthesia for Labour Flashcards

1
Q

List nerves associated with the perineum

A

BODY WALL
Somatic motor
Somatic sensory

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2
Q

List nerves associated with the pelvis

A

BODY CAVITY
Sympathetic
Parasympathetic
Visceral afferent

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3
Q

Which nerve structures transmit pain from the pelvis?

A

Visceral afferents - sympathetic or parasympathetic

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4
Q

Which nerve structures transmit pain from the perineum?

A

Pudenal nerve - somatic sensory

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5
Q

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

A

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

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6
Q

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

A

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

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7
Q

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

A

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

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8
Q

Structures above levator ani are supplied by which nerve fibres?

A

IN PELVIS

Visceral afferents

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9
Q

Structures below levator ani are supplied by which nerve fibres?

A

IN PERINEUM

Pudenal nerve

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10
Q

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

A

Spinal anaesthetic

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11
Q

What type of anaesthesia targets subperitoneal and somatic structures?

A

Epidural anaesthetic

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12
Q

What type of anaesthesia targets somatic structures only?

A

Pudenal nerve block

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13
Q

Spinal cord becomes cauda equina at what vertebral level?

A

L2 vertebra

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14
Q

SAS ends at which vertebral level?

A

S2

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15
Q

Anaesthesia is injected into which vertebral region?

A

L3-L4 to anaesthetise cauda equina

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16
Q

What is the surface landmark for injecting anaesthesia?

A

L4 spinous process

Superior point on iliac crests

17
Q

Describe the layers a needle passes through for spinal anaesthetic

A
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
Dura matter
Arachnoid matter
SAS with CSF
18
Q

Describe the layers a needle passes through for epidural anaesthetic

A

Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space

19
Q

What is the distinguishing feature of ligamentum flavum?

A

Yellow as it is elastic

20
Q

Describe sympathetic outflow below L2 vertebra

A

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

21
Q

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

22
Q

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

A

All arterioles

Vasodilatation

23
Q

List signs that spinal anaesthetic is working

A

Flushed lower limbs
Warm lower limbs
Reduced sweating

24
Q

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

A

False

Supplies most of it - also supplied by ilioinguinal nerve

25
Outline the route taken by the pudenal nerve to structures of the perineum
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
26
What is the pudenal canal?
Passage in obturator fascia containing internal pudenal artery and vein, pudenal nerve and nerve to obturator internus
27
Which bony landmark is used in the administration of pudenal nerve block?
Ischial spine
28
List instances in which a pudenal nerve block can be applied
Labour Forceps delivery Vaginal delivery Epiostomy
29
During labour, branches of which nerve can be torn?
Pudenal nerve (supplying levator ani and external anal sphincter)
30
Which component of the levator ani is typically torn fist during labour?
Puborectalis
31
How is tearing in the perineum during childbirth described?
First degree Second degree Third degree
32
What is the clinical significance of damage to dtructures due to perineal tearing?
Weakened pelvic floor | Faecal incontinence
33
What is an 'epiostomy'
A surgical cut made at the opening of the vagina during childbirth, to aid a difficult delivery and prevent rupture of tissues
34
List types of epiostomy incision
Posterolateral | Median
35
A posterolateral epiostomy incision is made into which anatomical structure?
Ischioanal fossae
36
A median incision is not used as often as it can damage which structure?
External anal sphincter if further tearing occurs posteriorly
37
The pudenal canal passes on the surface of which muscle?
Obturator internus