Anatomy Flashcards
what are the functions of the bony pelvis
supports upper body when sitting and standing
transfer weight from vertebral column to the femurs to allow standing/ walking
attachment for muscles of locomotion and abdominal wall
attachment for external genitalia
protection of pelvic structures
passage of childbirth
what makes up the bony pelvis
2 hop bones
sacrum
coccyx
what makes up the pelvic girdle
sacrum
2 hip bones
what bones make up the hip bones
ilium
ischium
pubis
is the coccyx part of the pelvic girdle
no
what ages do the hip bones fuse
ischium and pubis fuse at 8
ilium doesn’t fuses with the other bones until 20s
what muscle sits in the iliac fossa
iliacus
what is the ischiopubic ramus
where the ischium and pubis fuse
what creates (bone boundaries) the pelvic inlet
sacral promontory (prominent part of sacrum as it goes into the inlet)
ilium
superior pubis ramus
pubic symphysis
what are the boundaries of the pelvic outlet
pubic symphysis ischiopubic ramus ischial tuberosities sacrotuberous ligaments coccyx
what is the pelvic brim
bony edge of the pelvic inlet
what divides the pelvic cavity and the abdominal cavity
nothing they are continuous
what divides the pelvis and the perineum
the pelvic floor
what are the palpable landmarks of the pelvis
pubic symphysis pubic tubercle ASIS iliac crest sacrum coccyx ischial tuberosity PSIS ischial sines (on vaginal exam, approx 4 and 8 o'clock positions)
where do inguinal ligaments attach
between the ASIS and the pubic tubercle
what type of joint is the hip joint
synovial
what type of joint is the pubic symphysis
secondary cartilaginous
what type of joint is the SI joint
anterior aspect is synovial
posterior is a syndesmosis (fibrous ligaments)
what does the sacrospinous ligament attach between
sacrum and ischial spine
what does the sacrotuberous ligament attach between
sacrum and ischial tuberosity
what is the role of the sacrotuberous and sacrospinous ligaments
ensure the inferior part of the sacrum is not pushed superiorly when weight is suddenly transferred vertically through the vertebral column (jumping/ late pregnancy)
what do the sacrotuberous and sacrospinous ligaments form
greater and lesser sciatic foraminae
what notches form the sciatic foraminae
greater and lesser sciatic notches
what forms the obturator canal
obturator foramen and obturator membrane
what passes through the obturator canal
obturator nerve and vessels
what do fractures of the bony pelvis tend to involve
fractures in more than one place
joint dislocation
nerve/ vessel damage (life threatening haemorrhage)
damage to pelvic organs
how is the female pelvis different to the males
subpubic angle (and pubic arch) is wider
pelvic cavity shallower
AP (anterior posterior) and transverse diameters larger at both pelvic inlet and outlet
coccyx less curved - more room in pelvic outlet
males is heart shaped, females pelvic cavity more circular
males have more narrow sciatic notch
what is moulding
the movement of skull bones over one another to allow the foetal head to pass through the pelvis during labour
what allows moulding
presence of sutures and fontanelles
what are the fontanelles
anterior and posterior fonatelles (softs spots in skulls)
what is the vertex
area of the foetal skull- diamond shape from anterior, posterior fontanelles and the parietal eminences
is the occipitofrontal or biparietal diameter long in the foetal skull
occipitofrontal (foetal head is longer than it is wide)
why is the vertex important
as enables you to tell the position on the babies head in the womb
which diameter of the pelvis is wider
at pelvic inlet transverse is wider than AP
at outlet the AP diameter is wider than transverse
what is the orientations of the foetal head during childbirth
should enter pelvic cavity facing (transverse) right/ left direction
when descending through cavity head should rotate to OA (occipitoanterior) and be in flexed position (chin on chest)
should leave cavity (outlet) in OA position
in delivery head should be in extension
what is the station
the distance of the foetal head from the ischial spines = -ve number means head is superior, +ve number means head inferior
what rotation occurs after head is delivered
turned transversely and pulled down to delivery right shoulder, then up to deliver left
what vessels can haemorrhage in pelvic trauma
common iliac artery and vein
what nerves can be damaged in pelvic trauma
lumbo sacral plexus
what nerve block are is marked by the ischial spines
pudendal
describe the path of the pudendal nerve
goes medial to ischial spine, leaves via greater sciatic foramen then comes back into pelvis via lesser sciatic foramen, winding under sacrospinous ligament
what structures does the pudendal nerve innervate
levator ani
what levels does the pudendal nerve originate from
L2,3,4
when does the anterior fontanelle close
18 months- 2 years
what does a sunken/ raised fontanelle mean
sunken= dehydrated raised= high ICP, hydrocephalus
what is anterior shoulder dystonia
when babies shoulder is stuck behind pubic symphysis
what organs are in the female pelvic cavity
ovaries, uterine tubes, uterus, superior part of vagina
what is the only true/primary organ of reproduction in females
ovaries
what does the levator ani muscle divide
the perineum and the pelvic cavity
what does the inferior part of the pareital perineum form
- floor of peritoneal cavity
- roof over pelvic organs- covers superior aspect of organs
what are the two pouches in females
vesico-uterine (utero-vesico)
recto-uterine (pouch of Douglas)- deepest
how can a fluid collection in Pouch of Douglas can be drained
via a needle passed through the posterior fornix of the vagina
what is the peritoneum
very thin serous membrane layer that completely covers internal aspect of abdomen. Touching organs visceral, touching body wall parietal
what pouch do males have
rectovesicle
which pelvic organs are not subperitoneal
uterine tubes- these are intra peritoneal (within broad ligament)
what is the broad ligament
double layer of peritoneum that extends between the uterus and the lateral walls and floor of the pelvis
what is the role of the broad ligament
helps maintain the uterus in its correct midline position
contains the uterine tubes and the proximal part of the round ligament
are the fimbrae within the broad ligament
no open into peritoneal cavity
what is the round ligament
an embryological remnant of the gubernaculum -guides ovaries/testes down from abdo wall into final position
what is the path of the round ligament
attaches to the lateral aspect of the uterus
passes through the deep inguinal ring to attach to the superficial tissue of the female perineum
proximal part within the broad ligament
what is in the inguinal canal in females
round ligament of uterus
ilioinguinal nerve
what are the layers of the uterus body
perimetrium (outer layer)
myometrium (muscle layer - cramps and stretching)
endometrium (sheds during menstrual cycle)
what is an ectopic pregancy
implantation of a zygotes outwith the body of the uterus
where do most ectopic pregnancies occur
in the fallopian tubes
can occur in ovaries or abdomen
what is the risk at 8 weeks in ectopic pregnancies
rupture of fallopian tube
what holds the uterus in position
strong ligaments - uterosacral
endopelvic fascia
muscles of the pelvic floor - levator ani
what does the uterosacral fascia run between
cervix and sacrum
what is a uterine prolapse
movement of the uterus inferiorly
what is the most common position of the uterus
anteverted and anteflexed
-anterverted= cervix tipped anteriorly relative to the axis of the vagina
anteflexed= uterus tipper anteriorly relative to the axis of the cervix (mass of uterus lies over the bladder)
when does the uterus rise outwith the pelvic bones
12 weeks gestation
what is normal variation of the uterus position
retroverted and retoflexed
retroverted= cervix tipped posteriorly relative to the axis of the vagina retroflexed= uterus tipped posteriorly relative to the axis of the cervix
what zone must be sampled in a cervical smear
the squamo columnar junction (transformation zone)
where does fertilisation take place
in the ampulla
what is a bilateral salpingo-oophrectomy
removal of both uterine tubes and ovaries
what is a unilateral salpigectomy
removal of one of the uterine tubes
how can PID cause peritonitis
as fimbrae are communication between genital tract and peritoneal cavity
is a hysterosalpingogram what does radiopaque dye within the peritoneal cavity suggest
uterine tube is patent
how big are the ovaries
almond sized
what hormones do the ovaries secrete
oestrogen (FSH stimulated) and progetserone (LH stimulated)
where do the ovaries develop
on posterior abdominal wall
where are ovaries
ovarian fossa, on lateral walls of pelvic cavity
why is a speculum needed for a smear test
as vaginal walls usually in contact
what is a fornix
space around cervix, formed as cervix holds superior aspect of vagina apart
what are the four parts of the fornix
anterior, posterior and 2x lateral
what can be palpates on vaginal digital exam
ischial spines (4 and 8 o clock positions) position of the uterus (e.g. anteverted) adnexae (= uterine tubes and ovaries together) (place examining fingers into lateral fornix, press deeply with other hand in the iliac fossa on same side- can detect large masses/ tenderness)
what is the perineum
shallow space between the pelvic diaphragm (levator ani) and skin
what are the two triangles of the perineum
urogenital and anal
what are the parts of the levator ani muscle
skeletal (voluntary control, majority) and smooth (tonic and reflex contraction - increased intraabdominal pressure (sneezing, lifting heavy objects)_
what is the nerve supply to the levator ani
‘nerve to levator ani’
- S3,4,5
- dual supply form pudendal
what nerve supplys the perineal muscles
pudendal
what is the perineal body
bundle of collagenous and elastic tissue into which the perineal muscles attach
important for pelvic floor strength
locates just deep to skin
what are the bartholins glands
secrete mucous/ lubrication for anterior opening of vagina
what is the male version of bartholins glands
koupers gland
what type of tissue is erectile in females
clitoris and crura
where is the bed of breast tissue found
ribs 2-6
lateral border of sternum to mid axillary line
lie of deep fascia covering pec major and serratus anterior
what is the retro mammary space
lies between fascia and breast, allows breast to move independently of muscles
what attaches the breast to the skin
supsensory ligaments
what is within the breat
suspensory ligaments
fat
lactating and non lactating lobules
lactiferous ducts
what does a fixed mass in breast mean
has grown through to pectoral fascua
to assess whether fixed ask patient to place hands firmly on hips (contracts pec muscle)
what are the four quadrants of breast called
upper and lower inner
upper and lower outer
what quadrant is the axilary tail of breast in
upper outer
describe the lymph drainage of the breast
75% will drain to ipsilateral axillary lymph nodes then to supraclavicular nodes
lymph from inner quadrants can drain to the parasternal lymph nodes
lymph from lower inner can drain to abdominal lymph nodes
what can happen in axillary nodes removed in treatment of breast cancer
can get lymphedema as upper limb also drains to here
what is in the axilla
brachial plexus branches
axillary artery (& branches) and axillary vein (& tributaries)
axillary lymph nodes
all embedded in axillary fat
what are the levels use of axillary nodes to describe the extent of “axillary node clearance”
all in relation to pec minor:
Level I – inferior and lateral to pectoralis minor
Level II – deep to pectoralis minor
Level III – superior and medial to pectoralis minor
what is the blood supply to the breast
lateral thoracic and internal thoracic (aka internal mammary) from the subclavian and axillary
same venous drainage
which nerve types supply structures in the pelvis
body cavity so sympathetic, parasympathetic and visceral afferent
which nerve types supply structures in the perineum
body wall so somatic motor and sensory
what innervation controls uterine contraction (cramping in menstruation and during labour)
hormonal- sympathetic and parasympathetic
what innervation controls pelvic floor muscle contraction (e.g. during sneezing)
somatic motor
what nerve type carries pain from adnexae (ovaries + fallopian tubes) and uterus
visceral afferents
what nerve type carries pain from the vagina
visceral afferents (pelvic part) and somatic sensory (perineum)
what nerve type carries pain from the perineum
somatic sensory
how do sensory nerves from superior aspects of pelvic organs/ touching the peritoneum reach the CNS
what does the mean for pain perception
visceral afferents
run alongside sympathetic fibres
enter spinal cord between T11-L2
pain is perceived as suprapubic
how do sensory nerves from the inferior aspect of pelvic organs / not touching peritoneum reach the CNS
what does the mean for pain perception
visceral afferents
run alongside parasympathetic fibres
enter spinal cord at levels S2,3,4
pain perceived in S2,3,4 dermatome (peritoneum)
how do sensory nerves from Structures crossing from pelvis to perineum above levator ani (in the pelvis) reach the CNS
visceral afferents
parasympathetic
spinal cord levels S2, S3 and S4
how do sensory nerves from Structures crossing from pelvis to perineum below levator ani (in the perineum) reach the CNS
somatic sensory
pudendal nerve
spinal cord levels S2, S3 and S4
localised pain within perineum
what is the origin of the sympathetic nerves supplying the pelvis
Sacral sympathetic trunks
T11-L2
Superior hypogastric plexus
what is the origin of the parasympathetic nerves supplying the pelvis
Sacral outflow (S2, 3, 4)
Pelvic splanchnic nerves
Emerge from spinal roots
Mixes with sympathetics in inferior hypogastric plexus
(splanchnic nerves are paired visceral nerves, carrying fibers of the autonomic nervous system (visceral efferent fibers) as well as sensory fibers from the organs (visceral afferent fibers). All carry sympathetic fibers except for the pelvic splanchnic nerves, which carry parasympathetic fibers)
visceral afferents back to T11-L2 are from what in females
pelvic organs which touch the peritoneum:
uterine tubes
uterus
ovaries
visceral afferents back to S2-S4 are from what in females
pelvic organs inferior to peritoneum:
cervix
superior vagina
pudendal nerves back to S2-S4 are from what in females
organs/structures within the perineum: inferior vagina perineal muscles glands skin
how do you tell whether pelvoc body cavity structures have autonomic or visceral afferent innervation
touching peritoneum?
yes= more superior= follows sympathetics back= T11-L2
no= more inferior= follows parasympathetics back= S2,3,4
what levels does the spinal cord become the cauda equina
L2
what level does the subarachnoid space end
S2
what level is an epidural injected
L3-4 (L5) region (usually in line with most superior point on iliac crest (L4-5 space)
what does the needle pass through in an epidural
skin subcutaneous tissue supraspinous ligament interspinous ligament ligamentum flavum epidural space (fat and veins)
what level is a spinal anaesthetic done
L3/4
what does the needle pass through in a spinal anaesthetic
skin subcutaneous tissue supraspinous ligament interspinous ligament ligamentum flavum epidural space (fat and veins) dura mater arachnoid mater subarachoidnoid space (contains CSF)
where do sympathetic nerves exit the spinal cord
T1-L2
what is the path of sympathetic nerves from spinal cord
exit T1-L2
Travel to sympathetic chains running the length of vertebral column
Pass into all spinal nerves (anterior and posterior rami / named nerves)
what happens to sympathetic nerves below L2 level
sympathetic ganglia receive fibers from L2 level via the sympathetic chain and distribute them via connections with lumbar, sacral and coccygeal spinal nerves
do the femoral, sciatic, obturator and pudendal nerves all have sympathetic fibres
yes- All spinal nerves and their named nerves contain sympathetic fibres
are all arterioles supplied by sympathetic fibres
yes- provide sympathetic tone
what does blockade of sympathetic tone to all arterioles in the lower limb cause
= Vasodilation
- skin of lower limbs looks flushed
- warm lower limbs
- reduced sweating
(all these signs that spinal anaesthetic is working
can cause hypotension
what supplies the somatic motor and sensory to the perineum
pudendal
what is the pudendal nerve a branch of
sacral plexus S2,3,4
what will a pudendal nerve block make numb
majority of perineum
what is the path of the pudendal nerve
exits pelvis via greater sciatic foramen
passes posterior to the sacrospinous
ligament
re enters pelvis/ perineum via lesser sciatic foramen
travels in pudendal canal (passageway within obturator fascia) with internal pudendal artery and vein and nerve to obturator internus
branches to supply to perineum
what can be used as a landmark in a pudendal nerve block
ischial spin can be use to find where it corsses the lateral aspect of the sacrospinous ligament
when is a pudendal nerve block given
during labour- forceps delivery, painful vaginal delivery, episiotomy incision
perineal suturing post delivery- LA is injected along site of tear/ episiotomy to anaesthetise branches of pudenda;
what can be damaged in vaginal delivery
branches of pudendal nerve fibres stretched
fibres within levator ani (puborectalis) or external anal sphincter can be torn which weaken the muscle (can be 1sr, 2nd or 3rd degree tears)
as a result= weak pelvic floor and faecal incontinence
what is an episiotomy
posterolateral (or mediolateral but this puts anal sphincter at risk) incision made into relatively safe fat filled ischioanal fossa
this avoids the incision extending into the rectum
what incision is made in a lower segment CS and an abdominal hysterectomy
suprapubic/ pfannenstiel/ bikini line incision
what incision for a laparotomy
vertical midline
what should you follow when making incisions if possible
langer lines
what are the layers of the anterolateral abdo wall
skin
superficial fascia
(medial= rectus sheath, rectus adnominus)
(lateral= external and internal oblique then transversus abdominus)
what are the attachments of the external obliques
lower ribs
iliac crest
pubic tubercle
linea alba
what is the linea alba
midline blending of the aponeuroses
what direction do the fibres of the external obliques run in
hand in pockets- same as external intercostals
what are the attachments of the internal obliques
lower ribs
thoracolumbar fascia
iliac crest
linea alba
what direction do the fibres of the internal obliques run in
hands on chest- same as internal intercostals
what are the attachments of the transversus abdominis
lower ribs
thoracolumbar fascia
iliac crest
linea alba
what direction do the fibres of the transversus abdominis run in
directly across
what are the tendinous intersections of the rectus abdominis
divide each side into 3/4 smaller muscles
improves mechanical efficiency
what does the linea alba attach to top and bottom
xiphoid process
pubic symphysis
what is the rectus sheath
combined aponeuroses of anterolateral wall muscles that surrounds the rectus abdominis
what must be done after the rectus sheath is cut
is stitched close (is a strong fibrous layer) to increase the strength of the wound and reduce risk of incisional hernias
what part of rectus sheath is cut in a suprapubic incision
only anterior rectus sheath (not posterior)
what nerves become the thoracoabdominal nerves
7th - 11th intercostal nerves
what is the nerve supply to the anterolateral abdominal wall
7th-11th intercostal nerves -> thoracoabdominal nerves
subcostal (T12)
iliohypogastric (L1)
ilioinguinal (L1)
where do the nerves that supply the anterolateral abdo wall travel
from lateral direction, in plane between internal oblique and transverse abdominis
what is the blood supply to the anterior abdominal wall
superior epigastric arteries (continuation of internal thoracic): lies posterior to rctus abdominis
inferior epigastric arteries (branch of external iliac): lies posterior to rectus abdominis
what is the blood supple to the lateral abdominal wall
intercostal and subcostal arteries
continuations of posterior intercostal arteries
what is the best way to incise muscle
incise in same direction as fibres to minimise traumatic injury avoid nerves (esp motor nerves) avoid interrupting blood supply
what is cut in a lower lower segment C section
skin superficial fascia anterior rectus sheath- pulled apart in lateral direction (moving rectus abdominis towards their nerve supply) fascia peritoneum (retract bladder) uterine wall amniotic sac
what layers need to be stitched closed after a LSCS
skin
fascial layer if high BMI
rectus sheath
uterine wall with visceral peritoneum
what layers to you go through in a laparotomy
skin
fascia
linea abla
peritoneum
what layers need to be stitched closed after a laparotomy
peritoneum and linea alba
fascia (if high BMI)
skin
midline incisions are relatively bloodless- what are the implications of this
healing may not be as good- increases wound complications (dehiscence, incisional hernia)
what site is a laparoscopy done at
sub umbilical incision may be all that is required lateral port may be required
what must be avoid in laparoscopy lateral ports
inferior epigastric artery
in laparoscopy, how can the position of the uterus be manipulated to view pelvic organs bettter
grasping the cervix with forceps inserted through the vagina
what is the path of the inferior epigastric artery
branch of external iliac
emerges medial to the deep inguinal ring (deep inguinal ring is halfway between asis and pubic tubercle)
then passes in a superomedial direction posterior to the rectus abdominus
what is the difference between an abdominal and vaginal hysterectomy
abdo- removal of the uterus via an incision in the abdo wall (often same incision as for LSCS)
vaginal- removal of uterus via the vagina
how do you differentiate the ureter from the uterine artery in a hysterectomy
uterer passes inferior to the artery (water under the bridge)
ureter will often vermiculate (involute) when touched
what is the perineum
shallow space between levator ani and perineal skin
what are the contents of the perineum
distal ends of pelvic organs external genitalia perineal muscles blood and nerve supply lymphatic drainage
what passes through the levator ani muscle in men
rectum and urethra
what are the functions of the levator ani muscle
forms roof of perineum and floor of pelvis
supports pelvic organs and assists in maintaining faecal and urinary continence
what are the nerve roots of the pudendal nerve
S2,3,4
what type of nerve fibres does the pudendal nerve contain
somatic motor (to levator ani and muscles of the perineum) somatic sensory (from the perineum) sympathetic (as in all other spinal nerves)
what is contained within the ischioanal fossa
fat pad
pudendal canal (contains pudendal nerves and internal pudendal vessels)
inferior rectal branches of the pudendal nerve
lymphatics
where is the ischioanal fossa
lateral to the anal canal
why might a perianal abscess spread readily though the ischioanal fossa
as large space filled with fat and loose connective tissue
fat has poor blood supply and few immune cells- minimal barrier to spread of infection
what type of tissue is the crura and bulbs
erectile
what are the roles of the perineal muscles
males- assist in erection, ejaculation and in final part of micturition
females- assist in pelvic floor support
what can be damage in hysterectomy during ligation of the uterine artery
ureter
what is the path of sperm
seminiferous tubules, rete teste, epididymis, ductus (vas) deferens in spermatic cord, ejaculatory duct, prostatic urethra, membranous urethra, spongy urethra, external urethral meatus of penis
what is the only pouch in males
rectovesical
when a female is in anatomical position where will abnormal fluid collect
rectouterine (pouch of douglas)
how can fluid from the pouch of douglas be drained
via a needle placed through the posterior fornix of the vagina
name the structure formed by a double layer of peritoneum, extending between the uterus and the lateral pelvic walls and floor?
broad ligament
what is the uterine round ligament a remnant of
the gubernaculum
what is the role of the round ligament of the uterus
maintaining anteflexion of the uterus
what is uterine prolapse
when the uterus descends into the vagina
what can cause uterine prolapse
weakened pelvic support
increased intraabdominal pressure
what is a cystocele
hernial protrusion of bladder into vaginal wall
what is a rectocele
hernial protrusion of rectum into vaginal wall
what is the role of of the external urethral sphincter
final control of urination
what are the components of the fluid secreted by the seminal vesicles
proteins, enzymes, fructose, mucus, vitamin C, flavins, phosphorylcholine and prostaglandin
what is the main function of the fluid secreted by the prostate gland
activating sperm
what are the functions of the fluid/ mucus secreted by the bulbourethral (cowpers) glands
lubricates urethra and helps to neutralise acid in vagina
what is contained in the spermatic cord
ductus (vas) deferens, testicular artery, venous drainage (pampiniform venous plexus), sympathetic
nerve fibres, genital branch of genitofemoral nerve and lymphatics
what is the path of the vas deferens
begins at the tail of the epididymis, ascends through the scrotum posterior to the testis and medial to the epididymis, travels through the abdominal wall as part of the spermatic cord, crosses over the external iliac vessels to enter the pelvis, travels along the lateral wall of the pelvis and ends by joining the duct of the seminal gland to form the ejaculatory duct
where is the occiput in brow presentations
occipito POSTERIOR - head is not flexed when in this position
what way can a baby in the occiptio transverse position be rotated
to occipito anterior via manual rotation or using vaccum extraction/ kielland’s rotational forceps
what are the degrees of perineal tears
1st- skin, superficial
2nd- into perineum posterior to vagina
3rd- into anal sphincter
4th- both sphincters and anal mucosa
what is the posterior fourchette
small transverse fold just behind the vaginal opening where the labia minora meet each other
why is the ischioanal fossa important in women
where posterolateral episiotomies are made
what is the major structure incised in a medial episiotomy
perineal body
what is the path of the pudendal nerve
emerges from the pelvis and courses through the gluteal region through the greater sciatic foramen, below the piriformis muscle. It then turns forward around the sacrospinous ligament and leaves the gluteal region through the lesser sciatic foramen (between sacrotuberous and sacrospinous ligaments).
It is then directed into the pudendal canal, which lies on the obturator fascia above the falciform ridge on the ischial tuberosity.
They pass forward in the fascial canal (Alcock’s) on obturator internus (lateral wall of ischio-anal fossa), with the nerve usually lying inferior to the artery.
where is a needle inserted in a pudendal nerve block
palpate ischial spines vaginally
The pudendal nerve is immediately inferior to the tip of the spine and an anaesthetic needle may be passed through the vaginal wall, or through the overlying skin, aimed just below the ischial spine and at the pudendal nerve
As the fetus’s head is usually stationed within the lesser pelvis at this stage, it is important that the physician’s finger is always positioned between the needle tip and the baby’s head during the procedure.
what is the motor and sensory innervation provided by the pudendal nerve
The pudendal nerve is the main motor innervation to the perineum, as well as providing sensory innervation to most of the skin of the perineum and the external genitalia. It provides innervation to the perineal muscles, the external anal sphincter and external urethral sphincter.
are uterine contractions numbed by a pudendal nerve block
pudendal nerve block provides local anaesthesia over dermatomes S2–S4, which is the majority of the perineum, and the inferior quarter of the vagina. It does not block pain from the superior birth canal (uterine cervix and superior vagina), so the mother is able to feel uterine contractions.
what fetal nerve injuries can occur during birth
The fetal skull has no mastoid processes. These will form at around 4 years, drawn out by sternocleidomastoid as the child lifts its head. At birth there is no protection for the facial nerve (VII) emerging from the stylomastoid foramen and it may be injured during forceps delivery.
If an arm is delivered first, pulling on that arm to speed delivery could drag it into forced abduction which may put undue traction on the lower trunk of the brachial plexus (C8 and T1). This could cause Klumpke’s palsy, loss of the function of all the small muscles of the hand. There would be clawing of all the fingers and sensory loss on the medial aspect of the upper limb.
If the head is delivered, but the baby is “stuck” by a shoulder, then pulling on the head, particularly at an angle, may force the shoulder and neck apart, putting undue traction on the upper trunk of the brachial plexus (C5 and 6). This could cause Erb’s or “Waiter’s Tip” palsy, where the arm is adducted and internally rotated at the shoulder and the elbow is extended and pronated. Sensory loss is to the lateral aspect of the upper limb
what nerve injuries can be caused to the mother during birth
Keeping a patient in the lithotomy position for too long, with her legs and knees pressed hard up against side-supports, may cause neurapraxia of the common fibular (peroneal) nerve leading to a temporary foot-drop.
what does the needle pass through in a spinal anaesthetic
skin subcutaneous fat supraspinous ligament interspinous ligament ligamentum flavum epidural space (fat and blood vessels) dura arachnoid mater
what is the path of the needle in an epidural
inserted at L3/4 and passes through, or just to the side of the interspinous ligament, and through the ligamentum flavum to enter the epidural “space”. The anaesthetic spreads within the “space” to anaesthetise the emerging nerve roots
what levels is a spinal anaesthetic done
L3/4
where does the spinal cord end
L2
what position is the patient in when getting a spinal anaesthetic
chin to chest to curve lumbar spine and increase intervertebral space
the top of the iliac crest should be palpated – the plane between the two superior aspects of the iliac crests passes through the spinous process of L4. After deep palpation, the dimple between the spinous processes is identified as the point to insert the needle.
what are the potential side effects of a spinal anaesthetic
During a spinal anaesthetic an injection of local anaesthetic will mix with the CSF and rapidly block the nerve roots with which it comes in contact. It may be done for emergency Caesarean section. However, the spinal anaesthetic may cause post-spinal headache, and if it reaches the cervical cord in high enough concentration, may cause respiratory arrest.
what are the potential side effects of an epidural anaesthetic
the anaesthetic must block T10 to L1 in the first stage of labour, but extend to include S2 to S5 in the second stage. Clearly, such a block may well cause temporary, neurological side effects in the bladder and in the lower limbs. The patient may need urinary catheterisation, and be unable to walk
how long does a spinal anaesthetic take to work
10 mins
why must you aspirate before injecting a pudendal nerve block
to make sure not injecting into pudendal vessels (can cause seizures, arrest, local LA toxicity)
when is a spinal anaesthetic CI
obesity (morbid)
bleeding difficulties
infection
spinal surgery
why is hypotension a risk of regional anaesthetics
causes vasodilation
what are the three layers of the pelvic floor
pelvic diaphragm
muscles of perineal pouches (deep transverse perineal muscle, external urethral sphincter, compressor urethrae)
perineal membrane
what is the pelvic diaphragm
deepest layers of pelvic floor
made of levator ani (mostly) and coccygeus
what is the anterior gap between the medial borders of the pelvic diaphragm
urogenital hiatus= passage for urethra and vagina
where does the levator ani attach
puborectalis- pubic bones to around anus
pubococcygeus- pubic bones, creates a midline raphe near coccyx, joins with tendinous arch of levator ani
ilio-coccygeus- ischial spine to midline also joints to fibrous arch
all of these attach to onto perineal body and organs in midline
what is the fibrous arch of the levator ani
a thickened band of the fascia covering the inner aspect of the obturator internus muscle
what are the three parts of the levator ani
Puborectalis
Pubococcygeus
Iliococcygeus
what innervates the levator ani
pudendal and nerve to levator ani
when is the pevlic floor contracted
tonically contracted most of the time
actively contracts during coughing, sneezing, vomiting etc
other than muscles wheat else supports the pelvic organs
endo-pelvic fascia
- connective tissue
- some loose areolar tissue
- some fibrous (collagen and elastic)
pelvic pigaments -fibrous endopelvic fascia -uterosacral -transverse cervical (cardinal) lateral ligament of the bladder -lateral rectal ligaments
what is the cardinal pelvic ligament
transverse cervical
what are where is the deep perineal pouch
lies between fascia convering inferior aspect of pelvic diaphragm and the perineal membrane
contains:
- urethra
- vagina
- bulbourethral glands in males
- neurovascular bundle for penis/ clitoris
- extensions of ischioanal fat pads and muscles
what is the difference in the deep transverse perineal muscle in males and females
males- skeletal
females- smooth
what muscles assists the external urethral sphincter
compressor urethrae
what is the perineal membrane
thin sheet of tough deep fascia
superficial to the perineal pouch
attaches laterally to the sides of the pubic arch, closes urogenital triangle
has opening for the urethra and vagina in females)
what is the role of the perineal membrane
(with perineal body) is last passive support of the pelvic organs
wheres is the superficial perineal pouch
below the perineal membrane
what does the superficial perineal pouch contain in men
root of penis:
- bulb-> corpus spingiosum
- crura -> coprus cavernosum
- associated muscles: bulbospongiosus and ischiocavernosus
proximal spongy urethra
superficial transverse perineal muscle
branches of internal pudendal vessels
pudendal nerve
what type of tissue ans the bulb and crura
erectile
what forms the coprus cavernosum and spongiosum
spongiosum= bulb cavernosum= crura
which muscle of superficial perineal pouch doesnt insert into perineal body
ischiocavernosum
what does the superficial perineal pouch contain in females
Clitoris and crura – corpus cavernosum
Bulbs of vestibule – paired
Associated muscles – bulbospongiosus and ischiocavernosus
greater vestibular glands (bartholins- unlike male cowpers which are in deep perineal pouch)
superficial transverse perineal muscle
branches of internal pudendal vessels and pudendal nerve
what are the functions of the pelvic floor
supports pelvic floor
helps maintain continence
what muscles maintain urinary continence
External urethral sphincter, compressor urethrae, levator ani, smooth muscle in urethral wall, urinary bladder neck support
what muscles contain faecal continence
Tonic contraction of puborectalis bends the anorectum anteriorly
Active contraction maintains continence after rectal filling
anal sphincters
muscles of pelvic floor
what can cause injury to pelvic floor
pregnancy child birth chronic constipation obesity heavy lifting chronic cough or sneeze previous injury to pelvis/pelvic floor menpause
what is a vaginal prolapse
herniation of urethra, bladder, cervix, uterus, rectum or rectouterine pouch through supporting fascia
presents as lump in vagina
what are the types of vaginal prolapse
Cystocele- bladder protruding into anterior vaginal wall
Enterocele- bowel protruding into posterior vaginal wall
Urethrocele- urethra protruding into anterior vaginal wall
rectocele- rectum protuding into posterior vaginal wall
how does a uterine prolapse present
dragging sensation
feeling of lump
urinary incontinence
what are the degress of uterine prolapse
1st- cervix into upper vagina
2nd – cervix lower into vagina but still above the opening
3rd - cervix into open environment
4th - uterus and cervix outwith vagina
what are vaginal prolapses repaired
Sacrospinous fixation:
Sutures placed in sacrospinous ligament, just medial to the ischial spine
To repair cervical/vault descent
Performed vaginally
Risk of injury to pudendal NVB and sciatic nerve
Incontinence surgery: Trans-obturator approach Mesh through obturator canal Space in obturator foramen for passage of obturator NVB Create a sling around the urethra Incisions through vagina & groin
