Anatomy of Labour and Surgical Incisions Flashcards
what is the pelvic pain line
a threshold that determines the (afferent) course of visceral pain sensation
structures above the line (assoicated with the peritoneum) convey visceral pain sensation via sympathetic splanchnic nerves
structures below the line convey visceral pain sensation via parasympathetic splanchnic nerves
can organs refer pain via sympathetic and parasympathetic afferent fibres
yes, they can cross the pelvic pain line
where is pain from above the pelvic pain line perceived
as suprapubic (T11-L2 dermatome)- travelling in synmpathetic fibres and enters the spinal cord a these levels (sympa is a thoracolumbar outflow)
where is pain from below the pelvic pain line perceived
perineum - enters spinal cord at S2-4 after travelling with parasympathetic fibres
how is pain referred from structures that cross from the pelvis (below pelvic pain line) to perineum, eg urethra, vagina
the levator ani forms the pelvic floor, structures above are in the pelvis and below are in the perineum
structures above refer pain through parasympathetic fibres, below is somatis sensory innervation with the pudendal nerve
how is pain from the perineum perceived
localised pain in perineum - pudendal nerve (somatic sensory)
motor supply to levator ani
pudendal nerve and nerve to elvator ani (branches of sacral plexus)
outline the pathway of the pudendal nerve
- Leaves pelvis through greater sciatic foramen and re-enters through lesser sciatic foramen
- Wraps around ischial spine
- Now accompanied internal pudendal artery and vein through pudendal canal (Alcock’s canal – formed by fasica of obturator internus muscle)
Nerve gives off branches inside the canal
what is the pudendal canal formed from
fascia from the obturator internus
what is the clinical signficance of teh pudendal nerve being fixed in the canal
can get stretched or pulled eg during childbirth
outline the procedure for a pudendal nerve block
A pudendal nerve block is a form of analgesia occasionally given before vaginal childbirth, episiotomy and other minor vaginal procedures.
To administer a pudendal nerve block, the patient is placed in the lithotomy position, and the ischial spine is palpated transvaginally. Local anaesthetic is then injected into the tissues around the ischial spine. The procedure is then completed on the opposite side.
As the pudendal nerve is accompanied by the internal pudendal artery, it is essential to aspirate before injecting local anaesthetic – this ensures that local anaesthetic is not administered into the systemic circulation.
which nerve block is used if you want to stop the pain fromuterine contractions?
spinal anaesthesia - will anaesthetise everything from the waist down
what problems with arterioles does spinal anaesthesia also cause
as the basal vascular tone of arterioles is caused by the sympathetic system –> vasodilation –> flushed skin, warmth, reduced sweating –> hypotension
which additional nerve block is required to anaesthetise the anterior labia
ilioinguinal nerve
what major structure can be damaged in a median episiotomy
external anal sphincter –> faecal incontinence
which lines must you try to follow when making an incision
Langer lines - lines of skin tension
what are teh 2 layers of superficial fascia
campers fascia - outer fatty layer
scarpas fascia - inner membranous layer
outline the layers of the anterolateral abdominal wall
what is an aponeurosis
a flat, sheet like tendon
what is bledning at the line alba
midline blending of aponeuroses - eg contralateral ext oblique and int oblique will mesh together diagonally
where does the midline linea alba run from
xiphoid process to pubic symphysis
where is the linea semilunaris found
lateral boundary of rectus abdominus
why is teh rectus abdominus split into tendindous intersections
to improve mechanical efficiency
what is the significance of the arcuate line
above it the recuts abdominus is surrounded by a posterior and anterior rectus sheath
below it, there is only an anterior rectus sheath
why does such a change happen in the positioning of the layers of teh rectus sheath
Due to gravity most of the organs are located in the lower half of abdominal cavity – added protection
where abouts is the arcuate line
about a third down of the way from umbilicus to pubic symphysis
what is the inferior epigastric artery a branch of
what is the superior epigastric artery a branch of
continuation of internal thoracic artery
where do teh epigastric artries lie in relation to the rectus abdominus
posterior
which arteries are the intercostal and subcostal arteries a continuation of
posterior intercostal arteries
do the superior and inferior epigastric arteries connect?
yes they anastomose
how should you incise in relation to the direction of muscle fibres
same direction
outline the LSCS incision
suprapubic line
pull rectus muscles apart at midline linea alba
through what layers must you pass in a LSCS incision
skin and fascia
anterior rectus sheath
rectus muscle
fascia adn peritoneum
uterine wall
amniotic sac
what layers must be passed through in a laparotomy
skin a nd fascia
midline linea alba
peritoneum
what are teh consequences of the midline linea alba being a relatively bloodless structure, in terms of healing after a laparotomy
healing isnt as good and there is an increased chance of wound complication s
what type of hernia can occur through a surgical incision
incisional hernia
what artery is at risk of being damaged in a laparoscopy using a lateral port
inferior epigastric artery
what are the boundaries of Hesselbach’s triangle
what are teh 2 routes for a hysterectomy?
abdominal or vaginal
how does the ureter run in relation to the uterine artery
water under the bridge
