Anatomy Flashcards
The female reproductive system lies both within the _____ and the ______
pelvic cavity and the perineum
What parts of the female reproductive system are in the pelvic cavity?
ovaries, uterine tubes, uterus, superior part of vagina
What parts of the female reproductive system are in the perineum?
inferior part of vagina, perineal muscles, bartholin’s glands (greater vestibular glands), clitoris, labia
What is the perineum?
the area below the pelvic floor, it is a shallow space between the pelvic diaphragm and the skin
What is the only true female reproductive organ?
the ovaries (everything else is secondary/ accessory)
The peritoneum forms the __1__ of the abdominal cavity but ___2___ of pelvic cavity
1) floor
2) roof
As the peritoneum drapes over the reproductive organs it forms two pouches which are?
vesicouterine and rectouterine
What is the clinical significance of the rectouterine pouch? Why is this not quite true?
it is the lowest point of the peritoneal cavity in the upright female patient therefore any excess fluid will collect here, however there are often little lateral extensions that lie either side of the rectum (lateral para-rectal fossa) which are usually slightly deeper and can also collect fluid
The broad ligament of the uterus is a _____1_______ that extends between the ______2_______ and it helps ______3________ and it contains within it the ______4_________
1) double layer of peritoneum
2) sides of the uterus to the lateral walls and floors of the pelvis
3) maintain the uterus in its correct midline position
4) uterine tubes and the proximal part of the round ligament
The round ligament of the uterus is an _____1____ that attaches to the ___2_____ and passes through ____3___ to attach to ____4_____ the proximal part is contained within the _____5_______
1) embryological remnant
2) lateral aspect of the uterus
3) the deep inguinal ring
4) superficial tissue of the female perineum
5) broad ligament
What are the three layers of the uterine body?
perimetrium, myometrium, endometrium
The uterus is generally found in ______ unless _______
pelvic cavity unless pregnant will move up into abdominal cavity at about 12 weeks
Most common position of the uterus is?
anteverted and anteflexed
anteverted: the cervix is tipped anteriorly relative to the axis of the vagina
ante flexed: the uterus is tipped anteriorly relative to the axis of the cervix (the mass of the uterus lies over the bladder)
everything is tipped anteriorly to the next thing
A common normal variation of uterus position?
retroverted and retroflexed
Retroverted: cervix tipped posteriorly relative to the axis of the vagina
Retroflexed: uterus tipped posteriorly relative to the axis of the cervix
The vagina is essentially a ______ and the walls are usually ______
muscular tube
collapsed
the vagina is usually ___ long and extends from _______
7-9cm
superior most aspect of the vaginal part of the cervix of the uterus to the vaginal orifice the opening at the inferior end of the vagina
Fertilisation occurs in the _____ of the uterine tubes
ampulla of the uterine tubes
Parts of the uterine tubes from lateral to medial?
infundibulum, ampulla, isthmus, uterine part
Describe the ampulla of the uterine tubes?
this is the widest and longest part of the tube which begins at the medial end of the infundibulum
this is where fertilisation occurs
Describe the infundibulum of the uterine tubes?
the funnel-shaped distal end of the tube that opens into the peritoneal cavity through the abdominal osmium, the finger like processes of the fimbriated ends of the infundibulum (fimbriae) spread over the medial surface of the ovary
Describe the isthmus of the uterine tubes?
the thick walled part of the tube which enters the uterine horn
What is the ideal position of the uterine tubes? What is the reality?
tubes extend symmetrically posterolaterally to the lateral pelvic walls where they arch anterior and superior to the ovaries in the horizontally disposed broad ligament
in reality the tubes are commonly asymmetrically arranged with one or the other often lying superior and even posterior to the uterus
Explain how the oocyte expelled at ovulation passes into the peritoneal cavity?
because the ovary is suspended in the peritoneal cavity and its surface is not covered by peritoneum the oocyte expelled passes into the peritoneal cavity however its intraperitoneal life is short because it is normally trapped by the fimbriae of the infundibulum of the uterine tube and carried into the ampulla where it may be fertilised
The ovaries are ______ shaped and sized
They are gonads (primary reproductive organs) but also _________
almond
endocrine glands as they secrete oestrogen and progesterone in response to FSH and LH from the anterior pituitary gland
The vagina is a muscular tube whose walls are normally in contact except ____________
superiorly where the cervix holds them apart forming a fornix
Describe the vaginal fornix?
this is the recess around the cervix and contains anterior, posterior and lateral parts
What is the mons pubis?
this is the rounded fatty eminence anterior to the pubic symphysis, pubic tubercles and superior pubic rami, the eminence is formed by a mass of fatty subcutaneous tissue, the amount of fat increases at puberty and decreases after menopause, the surface of the mons is continuous with anterior abdominal wall and after puberty the mons pubis is covered with coarse pubic hairs
What is the vestibule of the vagina?
the space surrounded by the labia minora into which the orifices of the urethra and vagina and the ducts of the greater and lesser vestibular glands open
The roughly circular body of the female breast rests on a bed of the breast which extends from _______
ribs 2-6
lateral border of sternum to the mid-axillary line
Two thirds of the bed of the breast are formed by the ___1________ and the other third by ______2_____
1) pectoral fascia overlying the pectoralis major
2) fascia covering the serratus anterior
What lies between the fascia and the breast?
the retromammary space
The breasts are attached to the skin via _______
suspensory ligaments
Most lymph (>75%) from the breast drains to the ________________1______________
Lymph from inner breast quadrants can drain to the _______2_________
Lymph from the lower inner breast quadrant can drain to _______3_________
1) ipsilateral axillary lymph nodes and then to the supraclavicular nodes
2) parasternal lymph nodes
3) abdominal lymph nodes
Apart from lymph from the breast, lymph from where else drains to the axillary lymph nodes… why is this relevant?
from the upper lymph
if taking out these nodes due to a cancer then could cause upper limb lymphedema
What are the three surgical levels of axillary nodes?
Level I – inferior and lateral to pectoralis minor
Level II – deep to pectoralis minor
Level III – superior and medial to pectoralis minor
Describe blood supply to the breasts?
branches from the internal thoracic artery from the subclavian
branches from the axillary artery
What is the cervix?
the cylindrical, relatively narrow inferior third of the uterus
Describe the two parts of the cervix?
the supravaginal part which is between the isthmus (isthmus of uterus is the inferior narrow part of uterus) and the vagina
vaginal part which protrudes into the superior most anterior vaginal wall
What is the external and internal cervical os?
The internal os of the cervix is the opening of the cervix that joins the uterus, while the external os of the cervix is the junction between the cervix and the vagina
The pelvic floor is made up of 3 layers which are?
the pelvic diaphragm, the muscles of perineal pouches, the perineal membrane
The pelvic diaphragm is the ______ of the pelvic floor and consists of ___________
deepest (most internal)
two muscles: levator ani and coccygeus
3 parts of levator ani?
iliococcygeus, pubococcygeus, puborectalis
What forms most of the pelvic diaphragm?
levator ani
Levator ani is tonically contracted ___1___ it actively contracts when ___2____
1) most of time
2) coughing, sneezing or vomiting (basically anything that is increasing intrabdominal pressure)
Innervation of levator ani?
pudendal nerve and nerve to levator ani
note there is debate over whether there is a dual nerve supply
What provides additional support to the pelvic diaphragm?
endo-pelvic fascia:
some loose areolar tissue
some fibrous
collagen and elastic fibres
pelvic ligaments: fibrous endo-pelvic fascia uterosacral transverse cervical (cardinal) lateral ligament of bladder lateral rectal ligaments
The deep perineal pouch lies below ____1______ but above the ______2_________
1) the fascia covering the inferior aspect of the pelvic diaphragm
2) above the perineal membrane
What does the deep perineal pouch contain?
Contains part of the urethra (and vagina in females), bulbourethral glands in male, neurovascular bundle for penis/clitoris, extensions of the ischioanal fat pads and muscles (deep transverse perineal muscle in males or smooth muscle in females, both have the external urethral sphincter, compressor urethrae)
What muscles are contained within the deep perineal pouch?
external urethral sphincter, compressor urethrae
in males the deep transverse perineal muscle and in females a smooth muscle (debate around this)
The perineal membrane is ___1______ to deep perineal pouch. It is a ______2__________
It attaches _______3_______
It has openings for ________4________
Together with the perineal body, it is the ___________5___________
1) Superficial
2) Thin sheet of tough, deep fascia
3) laterally to the sides of the pubic arch, closing the urogenital triangle
4) the urethra (and vagina in females)
5) last passive support of the pelvic organs
The superficial perineal pouch lies __1___ the perineal membrane. In females it contains ____2_______
1) below
2) Contains female erectile tissue and associated muscle:
Clitoris and crura – corpus cavernosum
Bulbs of vestibule – paired
Associated muscles – bulbospongiosus and ischiocavernosus
Also contains greater vestibular glands, superficial transverse perineal muscle and branches of internal pudendal vessels and pudendal nerve
What does the superficial perineal pouch contains in males?
Contains root of penis:
Bulb – corpus spongiosum, crura paired – corpus cavernosum
Associated muscles – bulbospongiosus and ischiocavernosus
Also contains proximal spongy (penile) urethra, superficial transverse perineal muscle and branches of internal pudendal vessels and pudendal nerve
List the layers of the pelvic floor from deep to superficial?
pelvic diaphragm, deep perineal pouch, perineal membrane, superficial perineal pouch (first with erectile tissue then with the muscles of the superficial perineal pouch lying over them)
Injury to the pelvic floor related to obstetrics and gynaecology can occur because of?
pregnancy (increased pressure)
childbirth (stretching or tearing of the actual muscles or alternatively the pudendal nerve is damaged so muscles can’t be supplied properly)
What is the perineal body?
this is an important structure in support of the pelvic floor
its is where all the layers of the pelvic floor are linked and a number of muscles converge so provides a lot of support
Urinary continence depends on?
external urethral sphincter, compressor urethrae, levator ani
Faecal continence depends on?
Contraction of puborectalis muscle (part of levator ani) decreases the anorectal angle, acting like a sphincter. When the rectal ampulla is relaxed & filled with faeces, voluntary contraction of this muscle will help to maintain continence.
Describe how urinary continence is achieved?
As the bladder fills, this is sensed by stretch receptors at the end of visceral afferent nerve fibres
This information is relayed to the CNS via S2,S3,S4 spinal cord levels
There is a reflex at this point to empty the bladder by stimulation of the detrusor muscle and inhibition of the internal sphincter muscle
However in those infants who have been “potty trained” along with children and adults, the brain overrides this reflex; action potentials within inhibitory nerve fibres from the cortex pass inferiorly and inhibit this reflex. We can also voluntarily contract the external sphincter and levator ani muscles.
Describe what happens when it is appropriate to micturate?
Once it is appropriate to micturate:
The cerebral inhibition of this reflex is lifted and there is a co-ordinated contraction/relaxation of various muscles:
The detrusor muscle contracts (parasympathetic)
The internal urethral sphincter (parasympathetic), external urethral sphincter and levator ani muscles relax (somatic motor)
The anterolateral abdominal wall muscles contract to increase intra-abdominal pressure and force urine out of the external urethral orifice (somatic motor nerve fibres)
The external urethral sphincter and the levator muscles are supplied by?
branches of the pudendal nerve S2,3 and 4
and nerve to levator ani
Describe the prostatic urethra, the membranous urethra and the spongy urethra?
The prostatic urethra is the part that passes through the prostate and runs to the membranous urethra. The membranous urethra is the part passing through the perineal membrane that contains the striated muscle of the external urethral sphincter, which surrounds the urethra and is supplied by perineal branches of the pudendal nerve S2,3,4. The spongy urethra passes through the bulb of the penis and then into its corpus spongiosum.
What is the longest part of the male urethra?
the spongy urethra
Describe the male urethra?
internal urethral sphincter prostatic urethra membranous urethra and external urethral sphincter spongy urethra (penile urethra)
What are the borders of the urogenital triangle?
Borders: Theoretical line joining the two anterior ends of the ischial tuberosities, the pubic symphysis and the two ischiopubic rami
Describe the route of sperm once it leaves the testes?
From the testes the sperm passes into the epididymis into the vas deferens which passes superiorly within the spermatic cord to the deep inguinal ring. At the deep inguinal ring the vas deferens turns medially into the pelvis. The vas deferens joins with the duct of the seminal vesicle to form the ejaculatory duct which opens into the prostatic urethra. The prostatic urethra also contains prostatic ducts through which the glandular secretions from the prostate drain into the prostatic urethra.
Describe the location of the prostate gland?
The prostate gland lies at the base of the bladder, around the urethra, anterior to the rectum
What ligaments in the pelvis form the greater and lesser sciatic foramen?
the sacrospinous and sacrotuberous ligaments
What almost completely fills the obturator foramen of the pelvis? What is the gap for?
Obturator membrane is a thickened membrane fascia that almost completely fills the obturator foramen of the pelvis
Obturator canal found at anterior superior aspect of obturator membrane and allows passage of the obturator neurovascular bundle
What are the attachment points of the levator ani muscle?
The levator ani attaches to the bodies of the pubic bone anteriorly, the ischial spines posteriorly and a thickening in the obturator internus muscle fascia called the tendinous arch of levator ani between the two bony sites on each side
What muscle forms most of the fleshy part of the lateral pelvic wall?
the obturator internus
Where does the obturator internus muscle originate from and where does it attach to?
it originates from the obturator membrane (which covers the obturator foramen) and the tendon passes through the lesser sciatic foramen between the two gemelli muscles (superior and inferior) to attach to the greater trochanter of the femur
The majority of arteries of the pelvis and perineum arise from ___1_____ the exceptions to this are _______2_____
1) the internal iliac artery
2) gonadal artery ie the ovarian or testicular artery (which arises around about L2 vertebral level from the abdominal aorta) and the superior rectal artery which is a branch/ continuation of the inferior mesenteric artery
The internal iliac artery usually splits into two main divisions ____1___ which is visceral in nature and the ___2____ which is parietal
1) anterior
2) posterior
Where do the gluteal arteries arise from?
the gluteal arteries inferior and superior usually arise from the posterior division
a relatively common anatomical variation however is that the inferior gluteal artery comes from the anterior division
Is there a lot of variation in arteries of the pelvis or is it fairly constant across individuals?
lots of variation
List some branches of the anterior division of the internal iliac artery in females?
obturator artery number of superior vesical arteries internal pudendal middle rectal uterine artery which gives off the vaginal artery, the vaginal artery gives off some inferior vesical arteries to the bladder
How could you identify the obturator artery?
obturator artery is one of the first branches of the anterior division of the internal iliac artery
it will always be heading off to the lateral pelvic wall and going through the obturator membrane to the anterior pelvic wall
What is the vaginal artery a branch of?
the uterine artery
In females where do the superior and inferior vesical arteries come from?
superior vesical arteries come off the anterior division of the internal iliac artery
inferior vesical arteries come off the vaginal artery
What are two arterial anastomoses in the female pelvis?
An anastomosis occurs between the uterine artery and the ovarian artery
An anastomosis occurs between the uterine artery and the vaginal artery (although vaginal artery is a branch of uterine they still extensively anastamose)
What is closely related to the uterine artery?
the ureter, which runs under it hence have to be careful in surgeries
What is the main artery of the perineum?
the internal pudendal artery
What are the branches of the internal pudendal artery in females?
gives off the inferior rectal artery, the perineal artery (which gives off some posterior labial arteries) and then terminates as the dorsal artery of the clitoris
How does the external iliac artery contribute to the blood supply of the female perineum?
the external pudendal artery (which is a branch of external iliac) gives off anterior labial arteries
Describe the main differences in the blood supply to the male pelvis vs female?
the inferior vesical artery is a big branch of the anterior division as opposed to in females where it is small branches off the vaginal artery
instead of uterine artery there is an artery to the vas deferens which usually comes off the inferior vesical arteries
Describe the blood supply to the male perineum?
Internal pudendal supplies most of the perineum
inferior rectal will branch from the pudendal
Perineal artery and posterior scrotal artery and deep artery of the penis are branches of the internal pudendal artery, the internal pudendal terminates as the dorsal artery of the penis
There is a branch that comes from the external iliac and that is the anterior scrotal artery
Most of the veins from the pelvis and perineum eventually drain into the ___1____ however some will drain via ___2____
1) external iliac into the systemic venous system
2) superior rectal vein into the hepatic portal system
In the pelvis the veins form a number of __1_____ of Most of the veins from the pelvis and perineum eventually drain into the ___2____ however some will drain via ___3____
1) venous plexuses
2) external iliac into the systemic venous system
3) superior rectal vein into the hepatic portal system
What is the significance of the lateral sacral nerves venous drainage?
they have a connection of the internal venous plexus of the vertebral column, internal collateral pathway to SVC or IVC and also provides a route or pathway for metastases
The obturator nerve is formed from the lumbar plexus from nerve routes ________
L2 L3 and L4
The sciatic nerve passes out of the pelvic cavity via the ____________
greater sciatic foramen
Describe the pelvic splanchnic nerves?
they come from the anterior rami of S2,3 and 4 and carry parasympathetic innervation
Is it easy to predict the lymphatic drainage of the pelvis?
no theres lots of variation
In general what is the pathway of lymph from the superior pelvic viscera?
external iliac nodes first
then to common iliac, then aortic, then thoracic duct, then venous system
In general what is the pathway of lymph from the inferior pelvic viscera?
internal iliac nodes, then to common iliac, aortic, thoracic duct, venous system
In general where does lymph from the superficial perineum drain?
to the superficial inguinal nodes
What is important to note about lymphatic drainage of the testes or ovaries?
the ovaries / testes are going to drain straight towards the lumbar/ aortic/ caval lymph nodes because they originated on the posterior abdominal wall hence everything related to them e.g. arteries, lymphatics, veins is related to posterior abdominal wall
These structures can say with certainty where they will drain
But with rest of organs the pattern isn’t particularly predictable
Describe where the superior, middle and inferior rectal arteries come from?
the superior rectal artery is a branch of the inferior mesenteric artery
the middle rectal artery is a branch of the anterior division of the internal iliac artery
the inferior rectal artery is a branch of the internal pudendal artery
Describe the route of the pudendal nerve?
comes from S2,3 and 4 anterior rami, it then passes posteriorly through the greater sciatic foramen before looping back through the lesser sciatic foramen
List the components of fluid secreted by the seminal vesicle?
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 (Cowper’s) glands?
Lubricates urethra and helps to neutralise acid in urethra
What structures are located in the spermatic cord?
ductus (vans) deferens, testicular artery, venous drainage (pampiniform venous plexus), sympathetic nerve fibres, genital branch of genitofemoral nerve and lympahtics
How can you hold the pelvis in the correct anatomical position?
ASIS and pubic tubercle should be in the same plane
Explain the arcuate line?
Above arcuate line the aponeuroses of the external oblique, the internal oblique, and the transversalis muscles invest the rectus muscle both anteriorly and posteriorly, below the arcuate line the aponeuroses remain intact anteriorly, but only the weak transversalis fascia and peritoneum separate the muscle mass from the abdominal viscera posteriorly
What does the hip bone consist of? What is it sometimes called and why?
consists of ilium, ischium and pubis
sometimes called the innominate bone which means no name as initially it wasn’t given its own name
The pelvic inlet is formed by _______
sacral promontory, ilium, superior pubic ramus, pubic symphysis
The pelvic outlet is formed by ________
pubic symphysis, ischiopubic ramus, ischial tuberosities, sacrotuberous ligaments, coccyx
The pelvic cavity lies between ________
the pelvic inlet and the pelvic floor
Describe the true pelvis vs the false pelvis ?
the true pelvis runs from pelvic inlet to pelvic floor and involves the pelvic organs and functions for childbirth
the false pelvis is the area of the pelvis above the pelvic inlet (mainly ilium) which supports abdominal organs
List all the points of the pelvis that should be palpable on patients?
iliac crest, PSIS, ischial tuberosity, coccyx, sacrum, ASIS, pubic tubercle, pubic symphysis
Internally on a vaginal exam what bony landmarks can be palpated and where?
sacral promontory
also the ischial spines- located at 4 oclock and 8 oclock
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 sacroiliac joint?
Diarthrodial
this means the most anterior part is synovial but the posterior part is a syndemoses and is a type of fibrous joint
2 main functions of the sacrospinous and sacrotuberous ligaments of the pelvis?
1) protection against sudden weight transfer (if weight of body comes down quickly the pelvis and sacrum want to rotate anteriorly and inferiorly which would cause the sacrum and coccyx to rise up but these ligaments stop them being pulled too far up)
2) the presence of these 2 ligaments also forms the greater and lesser sciatic foraminae
Describe the differences between the male and females pelvis?
The AP (anteroposterior) and transverse diameters of the female pelvis are larger than the male, both at the pelvic inlet and outlet
The subpubic angle (and pubic arch) in the female is wider than the male
The pelvic cavity is more shallow in the female
Bones of male pelvis are heavier
Sacral promontory much more prominent in male (so male inlet more heart shape vs a more round oval inlet in the female)
The greater sciatic notch/ foramen in female is much bigger than in males
What does moulding in reference to the fetal skull mean?
“Moulding” refers to the movement of one bone over another to allow the foetal head to pass through the pelvis during labour.
What is meant by the vertex of the fetal skull?
The vertex is an area of the foetal skull: outlined by the anterior and posterior fontanelles and the parietal eminences
IN FETUS
The occipitofrontal diameter is_____ than the biparietal diameter (i.e. the foetal head is _________)
longer
longer than it is wide
At the pelvic inlet, _______1_______
In the fetal skull the _________2_________________
The foetus should ideally enter the pelvic cavity facing _______3__________
1) the transverse diameter of the pelvis is wider than the AP diameter
2) occipitofrontal diameter is longer than the biparietal diameter
3) either to the right or left (transverse) direction
What are the longest diameters of the pelvic inlet and outlet?
at the pelvic inlet the transverse diameter is longer
at the pelvic outlet the anterior posterior diameter is longer
While descending through the pelvic cavity, the foetal head should _____________
rotate
be in a flexed position, i.e. chin on chest
The baby should ideally leave the pelvic cavity ___1_____
During delivery the fetal head should be in ___2____
1) in an occipitoanterior (OA) position (posterior part of babys skull touching mums anterior part)
2) extension
Describe an overview of the rotations a baby should make during delivery?
at the pelvic inlet, the foetal head should be transverse
as it descends through the pelvic cavity, the foetal head should rotate and it should be flexed
at the pelvic outlet, the foetal head should ideally lie occipitoanterior (OA) and extension of the head on the neck should occur
once baby’s head delivered there needs to be a further rotation to deliver the shoulders (as these will need to be in anteroposterior axis which is longer)
Once the baby’s head has delivered ____________
there is a further rotation so that the shoulders and the rest of baby can then be delivered
Explain how pain is transmitted the superior aspect of pelvic organs touching the peritoneum?
(superior is touching the peritoneum because this drapes over) Superior part of pelvic organs that are touching the peritoneum are carried by visceral afferents, travel with sympathetic fibres and enter spinal cord between T11 and L2 (because this is where sympathetic innervation is supplied to this area), pain sensation is still being carried in the visceral afferents they are just travelling alongside them. Pain is perceived as suprapubic.
Explain how pain is transmitted the inferior aspect of pelvic organs not touching the peritoneum?
(inferior aren’t touching peritoneum) they cant see the sympathetics so they travel alongside the parasympathetics that they can see, they just run alongside, still visceral afferents, because its parasympathetics they enter spinal cord at S2,S3 and S4, so pain is perceived in S2,3,4 perineum.
Explain how pain is transmitted from structures crossing from pelvis to perineum above the levator ani?
visceral afferents
Run alongside parasympathetics
spinal cord levels S2, S3 and S4
pain perceived in the perineum but less localised
Explain how pain is transmitted from structures crossing from pelvis to perineum below the levator ani in the perineum?
somatic sensory
pudendal nerve
spinal cord levels S2, S3 and S4
localised pain within perineum
Pain sensation supply from pelvic organs touching peritoneum e.g. uterine tubes, ovaries and uterus ____1______
Pain sensation from pelvic organs inferior to peritoneum e.g. cervix and superior vagina __2______
Pain sensation from structures within the perineum ____3_____
1) visceral afferents T11-L2
2) visceral afferents S2-S4
3) pudendal nerve back to S2-S4
What are the two important spinal cord levels involved in pain to the female reproductive system?
T11-L2
S2-S4
Explain difference between speed of effect and length of effect with spinal and epidural anaesthetic?
Epidural space has more tissue for anaesthetic to diffuse through
So spinal anaesthetic is faster acting but epidural is longer lasting
So spinal used more for emergency sections vs epidural for labour pain
Why is epidural or spinal anaesthetic injected into about level L3-L4?
Anaesthetic is injected into L3-L4 (L5) region because there is no risk of getting spinal cord which ends at L2 but still access to CSF which ends at S2. The spinal cord is solid so very likely to damage it but if cauda equina all the nerve roots are movable so put aside as needle brushes past. Don’t want to inject much lower as the bones of the sacrum are fused.
When inserting an epidural anaesthetic what layers does the needle pass through?
supraspinous ligament
interspinous ligament
ligamentum flavum
epidural space (fat and veins)
When inserting a spinal anaesthetic what layers does the needle pass through?
supraspinous ligament interspinous ligament ligamentum flavum epidural space (fat and veins) dura mater arachnoid mater finally reaches subarachnoid space (contains CSF)
Explain how you can tell that a spinal anaesthetic is working?
sympathetic fibres supply all arterioles so if inject into lower back there will be a blockade of sympathetic tone to all arterioles in the lower limb so will be massive vasodilation and skin will become flushed, warmer and be reduced sweating
(NOTE there is also a potential therefore for hypotension although usually drugs are given to stop this)
Explain the anatomy of a pudendal nerve block?
The pudendal nerve crosses the lateral aspect of the sacrospinous ligament
The ischial spine can be used as a landmark (4 and 8 oclock positions) in vaginal exam and basically use a flexible needle sheath and then insert needle into vagina
What is an episiotomy?
If during delivery think baby is going to tear pelvic floor muscles then make an incision because this is easier to repair than a tear
Can direct the tear away from the external anal sphincter . Direct tears towards ischioanal fossa so avoiding the rectum
The external obliques attach between ____________
The fibres run in a ___________
lower ribs and iliac crest, pubic tubercle and linea alba
Superolateral to inferomedial direction
The internal obliques attach between ____________
The fibres run in a _________
Attach between lower ribs, thoracolumbar fascia, iliac crest and linea alba
inferolateral to superiomedial directions
Transversus abdominus attach between ________
the fibres run in a _________
Attach between lower ribs, thoracolumbar fascia, iliac crest and linea alba
transverse direction
Why are there tendinous intersections between each rectus abdominus muscle?
it improves mechanical efficiency
Describe the linea alba and its attachments?
linea alba (white line)
formed by the interweaving of the muscle aponeuroses
Runs from the xiphoid process to the pubic symphysis
Defect/ opening for the umbilical ring for where fetal vessels were
The rectus sheath is found ________ and is ________ which ________
immediately deep to superficial fascia
combined aponeuroses of anterolateral abdominal wall muscles
surrounds rectus abdominus muslces
Where is the arcuate line found?
a third of the way between the umbilicus and pubic symphysis
What is the significance of the arcuate line?
From arcuate line inferiorly all the aponeuroses of the tendons combine anterior to the rectus abdominus muscles, so there is no tough rectus sheath posteriorly.
Above the arcuate line there is aponeurosis anterior and posterior.
List the layers of the anterolateral abdominal wall?
parietal peritoneum extra peritoneal fat transversalis fascia transversus abdominus internal oblique external oblique deep fascia superficial fascia skin
Describe how the dermatome map and peripheral nerve distribution is almost identical in the anterolateral abdominal wall?
there is no plexus formation so they are almost identical
there is a small difference because at L1 there is a split into iliohypogastric and ilioinguinal
Describe the nerve supply to the anterolateral abdominal wall?
enter from lateral direction
7th-11th intercostal nerves
become thoracoabdominal nerves- anterior rami
subcostal (T12) - anterior rami
iliohypogastric (L1)- from the lumbar plexus
ilioinguinal (L1)- from the lumbar plexus
Blood supply to the anterior abdominal wall is by?
superior epigastric arteries
inferior epigastric arteries
Describe blood supply to the lateral abdominal wall?
intercostal and subcostal arteries
continuations of posterior intercostal arteries (which come from the thoracic aorta)
emerge at lateral aspect
The superior epigastric arteries are a continuation of the ____________ they emerge at ______________ and lie ___________
internal thoracic artery
emerge at superior aspect of abdominal wall
posterior to the rectus abdominus
The inferior epigastric arteries are a branch of ________ they emerge _____________ and lie ______________
external iliac artery
inferior aspect of abdominal wall
posterior to rectus abdominus- they are part of the rectus sheath but the rectus sheath isnt very important at this point
What artery is important when thinking about making incisions for O and G surgery?
inferior epigastric
How can you be sure to avoid the inferior epigastric artery?
it emerges just medial to the deep inguinal ring (which is halfway between ASIS and pubic tubercle) then passes in a superomedial direction posterior to rectus abdominus
so want to put a port lateral to the deep inguinal ring
