clinical anatomy of anaesthesia for labour Flashcards
reproductive system has two types of nerve innervation?
- motor
- sensory
motor function of repro system
- uterine ‘cramping’ during constriction
- uterine contraction during labour
- pelvic floor muscle contraction during sneezing
sensory function of repro system
- pain from adnexae - ovaries and fallopian tubes
- pain from uterus
- pain from vagina
- pain from perineum
if structure is in pelvis i.e. body cavity nerve supply from?
- sympathetic
- parasympathetic
- visceral afferent
if structure is in perineum i.e. body wall where is nerve supply from?
- somatic motor and somatic sensory
what is above levator ani muscle
pelvis
what is below levator ani muscle
perineum
uterine cramping and uterine contraction is controlled by
- sympathetic/parasympathetic driven by hormones
pelvic floor muscle contraction is controlled by?
- somatic motor
pain from adnexae is from?
- visceral afferents
pain from uterus is from?
- visceral afferents
pain from vagina is from?
- visceral afferents (pelvic part)/somatic sensory (perineum)
> different as vagina is both above and below pelvic floor
pain from perineum?
- somatic sensory
peritoneum drapes over superior pelvic organs, so pain from superior aspect of pelvis travel in visceral afferent fibres that run alongside?
- sympathetic fibres
- enter spinal cord between T11-L2
pain is perceived from superior aspect of pelvic organs as?
- suprapubic
inferior aspect of pelvic organs/not touching peritoneum how does pain travel?
- travels along visceral afferents running alongside parasympathetic fibres
- enter spinal cord at levels S2, S3, S4
pain from inferior aspect of pelvic organs is percieved where?
- S2, S3, S4 dermatome (perineum)
pain from structures above levator ani - in the pelvis travel how?
- along visceral afferents
- run alongside parasympaethic fibes
- enter spinal cord levels at S2, S3, S4
pain from structures below levator ani - in the perineum (body wall) travel how?
- along somatic sensory fibres
- as part of pudendal nerve
- enter spinal cord levels S2, S3 and S4
- localised pain within perineum
sympathetic nerves travel down what?
- sacral sympaethic trunks
- T11-L2
- form superior hypogastric plexus
- provide visceral motor innervation
parasympathetic nerves originate form where?
- originate from sacral outflow (S2,3,4)
- emerge from spinal roots
- mix with sympathetics in inferior hypogastric plexus
parasympathetic nerves travel in what?
- pelvic splanchnic nerves
pain from female repro system - two important spinal cord levels are:
- T11-L2
- S2-S4
peritoneum touches bottom of uterus/sup aspect of vagina
levator ani separates divisions of what
- pelvis and perineum
- everything below = perineum
- everything above = pelvis
which pelvic organs touch peritoneum
- uterine tubes, uterus, ovaries
- travel via sympathetic fibres
- T11 - L2
which pelvic organs are inferior to peritoneum
- cervix, and superior vagina
- travel via parasympathetic fibres
- S2, S3 and S4
in perineum - ie below level of levator ani - inferior vagina, perineal muscles, glands and skin what is nerve information travelling by?
- somatic sensory information carried back in pudendal nerve
- to S2, S3 and S4
study flow diagram
spinal cord becomes cauda equina at what level?
- L2 vertebra
subarachnoid space ends at level of ?
- S2
anaesthetic is injected into which level?
- L3-L4 (L5) region
- intercristal plane determines levels of L4 spinous process (most superior point on iliac crests) however variety in intercritsal planes and should be careful when doing this
epidural needs to pass through which structures?
- interspinous ligament (runs between spinous processes)
- supraspinous ligament (run sup aspect of spinous processes)
- ligamentum flavum (makes popping sound)
-> loss of resistance and has entered epidural space (fat and veins) - bathes spinal roots in anaesthetic
spinal anaesthetic: needle passes through?
- supraspinous lig
- interspinous
- lig flavum
- epidural space
- dura mater
- arachnoid mater
- finally reaches SAS (between arachnoid and pia) contains CSF
- spinal anaesthetic is delivered here into CSF
all spinal nerves and their named nerves contain what?
- sympathetic fibres
sympathetic fibres supply?
- all arterioles
> thus blockade to sympathetic fibres blocks sympathetic tone to all arterioles in lower limb causing = vasodilation
what is risk of spinal anaesthetic to lower limb?
- vasodilation
- flushed, reduced sweating, warm lower limb
- hypotension can be caused - patient should be closely observed during this procedure
sympathetic fibres originate from where?
- arise form autonomic control centres of brain
- exit spinal cord with T1-L2 spinal nerves
- travel to sympathetic chains/trunks which make up whole vertebral column
- pass into all spinal nerves and ant and post rami or named nerves
below L2 level sympathetic ganglia receive fibres from what level?
- from L2 level via sympathetic chain
- distribute them via connections w lumbar, sacral and coccygeal spinal nerves
the pudendal nerve has what functions
- somatic nerve carrying somatic motor and sensory fibres and is known as nerve of perineum
- role in motor control of external anal and external urethral sphincters
where is pudendal nerve dervied from?
- branch of sacral plexus - S2, S3, S4
where is pudendal nerve derived from?
- branch of sacral plexus - S2, S3, S4
pudendal nerve exists pelvis via what?
- greater sciatic foramen
- and passes posterior to sacrospinous ligament (near ischial spine - its attachment site)
- re-enters pelvis/perineum via lesser sciatic foramen
- travels in pudenal canal
- branches to supply structures of perineum
the pudendal nerve crosses posteiror to lateral aspect of what?
- sacrospinous ligament
what part of pelvis can be used as a landmark for pudendal nerve block?
- ischial spine
when is pudendal nerve block administered?
- forceps delivery
- painful vaginal delivery
- episiotomy incision
-> also post delivery for perineal suturing
during labour branches of what nerve can be stretched?
- pudendal nerve
what fibres and muscle can be torn also during lavour?
- fibres within levator ani (puborectalis)
- external anal sphincter muscle could be torn
1st degree tear during labour
- skin
2nd degree - perineal muscles
3rd degree - partial anal sphincter involvement
4th degree - complete anal sphincter tear and bowel lining and weakened pelvic floor and fecal incontinence
what is an episiotomy?
- an incision into skin and perineal muscles
- incision is posterolateral incision into fat filled ischioanal fossa
- aim of this incision is to avoid any tearing or incision going towards anal sphincter
