clinical anatomy Flashcards
which bones make up the pelvis
midline sacrum
coccyx
hip bones (ilium, ischium and pubic bone)
functions of the pelvis
support of the upper body when standing and sitting
transference of weight from one long pole to two poles
attachment for muscle of locomotion and abdominal wall
protection of pelvic organs, blood and nerve supply etc
attachment for external genitalia
passage for childbirth
what are the boundaries of the true pelvis
superiorly: pelvic inlet
inferiorly: pelvic outlet
what makes up the pelvic inlet
sacral promontory of S!
alas of the sacrum
arcuate line of the ilium
pectineal line and pubic crest of the pubic bone
what are the borders of the pelvic outlet
the tip of the coccyx posteriorly
the inferior margin of the sacrotuberous ligament posterolaterally
the ischial tuberosities laterally
the pubic arch anteriorly
which diameter is wider at the pelvic inlet
transverse
which diameter is wider at the pelvic outlet
AP
what are the two most important pelvic ligaments
sacrospinous
sacrotuberous
where does the sacrospinous ligament attach
sacrum and ischial spine
where does the sacrotuberous ligament attach
ischial tuberosity and sacrum
features of a male pelvis
thick, robust bone narrow, deep pelvis heart-shaped, narrow pelvic inlet small pelvic outlet narrow subpubic angle round obturator foramen narrow greater sciatic notch
features of a female pelvis
thin, light bone wide, shallow pelvis rounded, wide pelvic inlet large pelvic outlet wide subpubic angle oval obturator foramen 90 degree greater sciatic notch
where do pelvic fractures most commonly occur
weaker areas pubic rami acetabulum sacroiliac joints alae of the ilium
which structures can be damaged in a pelvic fracture
iliac vessel and their branches nerves of the lumbosacral plexus autonomic nerve supply lymphatic drainage muscles (pelvic floor, lateral pelvic walls, thigh, gluteal region, abdominal wall) pelvic organs
palpable bony landmarks of the ilium
ASIS (and inguinal ligament)
iliac crest
PSIS
palpable bony landmarks of the ischium
ischial tuberosities ischiopubic ramus (deep) ischial spines (internal examination)
palpable bony landmarks of the pubic bone
pubic symphysis
pubic tubercle
ischiopubic ramus
palpable bony landmarks of the sacrum
median sacral crest
inferolateral angle
sacral hiatus
sacral promontory (internal examination)
what were roots make up the pudendal nerve
S2-4
what are the modalities of the pudendal nerve
sensory, sympathetic and somatic motor to the area and structures of the perineum
describe the clinically relevant course of the pudendal nerve (and its implication)
the nerve crosses the lateral aspect of the sacrospinous ligament, near its attachment to the ischial spine
injection of the pudendal nerve block near the ischial spine
which fontanelle is largest
anterior
what is the vertex
an area of the fatal skull bounded by the anterior and posterior fontanelles and the parietal eminences
which fontanelles are covered by the temporals muscle
sphenoidal and mastoid fontanelles
what is moulding
change of the shape of the skull during labour
bones pass over each other to allow passage through pelvis
what direction should the baby face when entering the pelvic inlet and why
left or right
the AP diameter of the babies head should line up with the transverse diameter of the pelvis
when descending through the pelvic cavity, what movements should the baby’s head make
rotate and flex
what is the preferred presentation when leaving the pelvic outlet
occipitoanterior
why is there a final rotation after the head has been delivered
to allow the shoulders and rest of the body to be delivered
how long does the anterior fontanelle remain open
18-24 months
when does the posterior fontanelle close
12 months
which fetal skull features are palpable in OA presentation
posterior fontanelle
sagittal suture
vertex
anterior fontanelle
which foetal skull features are palpable in OP presentation
anterior fontanelle
orbital margins
which fossa lies either side of the anal canal
ischio-anal fossa
where does the ischiopubic ramus pass
from the ischial tuberosity to the inferior aspect of the pubic body
which muscle passes though the greater sciatic foramen
piriformis (to attach to the greater trochanter)
which neuromuscular structures pass through the greater sciatic foramen
sciatic nerve
gluteal neurovascular bundles
what structure separates the deep and superficial perineal pouches
perineal membrane
why is the perineal membrane stronger in males
to support the penis
where does the perineal membrane attach
ischiopubic rami
perineal body
what is contained in the deep perineal pouch
deep layer of fascia
external urethral sphincter and deep transverse perineal muscle
perineal membrane
what is contained in the superficial perineal pouch
external genitalia
what is an episiotomy
a deliberate incision of the vagina and pelvic floor to prevent vaginal tears extending towards the rectum
where does the episiotomy incision commence
fourchette (small, transverse fold where the labia minora meet)
incision usually goes posterolateral
which muscle forms the lateral wall of the ischia-anal fossa
obturator internus
what does a pudendal nerve block do
local anaesthesia over dermatomes S2-S4
why might the facial nerve be damaged during labour
the fetal skull has no mastoid process, so there is no protection for the facial nerve emerging from the stylomastoid foramen
it can therefore be injured during forceps delivery
how can labour cause Klumpke’s palsy
if the arm is delivered first, and pulled to speed delivery, it can be moved into forced abduction resulting in traction on the lower trunk of the brachial plexus (C8 and T1)
how does Klumpke’s palsy present
loss of function of all small muscles in the hand
clawing of the fingers and sensory loss of the medial aspect of the upper limb
how can labour cause Erb’s palsy
if the head is derived but the shoulders are stuck, pulling on the head can put traction on the upper trunk of the brachial plexus (C5 and C6)
how does Erb’s palsy present
adduction and internal rotation of the arm at the shoulder
extension and pronation at the elbow
sensory loss of the lateral aspect of the upper limb
why might a women have a temporary foot drop after labour
too much time spent in a lithotomy position can cause neuropraxia of the common fibular nerve
what are the primary curvatures of the spine
thorax and sacrum
what are the secondary curvatures of the spine
cervical and lumbar
where does the adult spinal cord end
L1/L2
what anatomical structures does the needle pass through for a spinal anaesthetic
ski SC fat supraspinous ligament interspinous ligament ligamentum flavum epidural space dura mater arachnoid mater in SAS
complications of spinal anaesthetic
post-spinal headache
respiratory arrest if reaches the cervical cord
what is the epidural space
potential space between the dura mater and the overlying bones and ligaments of the vertebral canal
where is the needle inserted for spinal/epidural anaesthetic
L3/4
what is the difference in onset between spinal and epidural anaesthetic
spinal = fast acting epidural = slow acting
nerve supply to the vulva
anterior = L1 via ilioinguinal posterior = S2,3,4 via pudendal
describe the route of the afferents from the body and fundus of the uterus
travel with sympathetic and reach the spinal cord at T10-L2
nerve supply of the vagina
S2,3,4 via pudendal nerve
which vertebral levels must be blocked during the first stage of labour
T10-L1
which vertebral levels must be blocked int he 2nd stage of labour
S2-S5
what position should the patient be in for spinal anaesthetic
head lowered, to curve the lumber spines and increase the IV space
surface anatomy of the point of needle insertion for spinal anaesthetic
the plane between the two superior aspects of the iliac crests passes through the spinous process of L4
what is the function of the darts muscle
to raise the testis closer to the body in cold conditions
what is normal testicular volume
12-25 ml
where does the epididymis lie
posterolateral border of the testis
should the epididymis be palpable
normally it is difficult to palpate
if there is an obstruction it may be palpable
what are the functions of the testis
spermatogenesis
secretion of testosterone
what is the tunica albuginea
a tough fibrous capsule surrounding the testis
what is the tunica vaginalis
a double layer of peritoneum that encloses the testis and epididymis in the scrotum
what is a hydrocele
a collection of fluid between the parietal and visceral layers of the tunica vaginalis
what are the three parts of the epididymis
head, body and tail
where does the epididymis become the vas deferens
at the inferior pole of the testis the tail of the epididymis becomes the vas
where does the vas deferens lie in relation to the epididymis
medial on the posterior aspect of the testis
describe the course of the vas deferens from the scrotum into the pelvis
ascends within scrotum, through the spermatic cord to enter superficial inguinal ring
though inguinal canal and exits via the deep inguinal ring, lateral to the inferior epigastric artery
passed above and medial to the ureter as it descends into pelvis to meet seminal vesicle to form ejaculatory duct
blood supply to the vas
artery to the vas, derived from the superior vesical artery
which ducts lie laterally to the urethral crest
many prostatic ducts
seminal colliculus/veru montanum
what is the seminal colliculus
opening of the ejaculatory ducts
prostatic bloody supply
branches of the inferior vesical artery
drained by a plexus of prostatic veins to internal iliac
how can tumour spread from the prostate
through an anastomosis between the prostatic venous plexus and valveless veins of the internal vertebral plexus
course of sperm
pass through vas, expelled into prostatic urethra along with secretions from seminal vesicles and prostate
propelled along membranous urethra, then penile (spongy) urethra
function of seminal vesicles
produce semen into ejaculatory duct supply fructose secrete prostaglandins (motility) secrete fibrinogen (clot precursor)
function of prostate gland
produces alkaline fluid (neutralised vaginal acidity)
produces clotting enzymes to clot semen within female
function of bulbourethral glands
secrete mucus to act as lubricant
what structures form the root of the penis proximally and the body of the penis distally
corpus spongiosum
corpora cavernosum
where is the bulb of the penis attached
perineal membrane
which muscle surrounds the corpus spongiosum
bulbospongiosus
why does the corpus spongiosum have a thin surrounding fascia
to prevent occlusion of the urethra
where do the corpora cavernosum attach
ischiopubic rami
which muscle surrounds the corpora cavernosum
ischiocavernosus
what does the expression ‘point and shoot’ mean
point
parasympathetic control blocks sympathetic vasoconstriction and allow increased blood flow to form erection
shoot
sympathetic control of muscles involved in ejaculation
where do the testicular/ovarian arteries arise
L2 aorta
where does lymph from the testis drain
para-aortic nodes
why is testicular and ovarian pain referred to the peri-umbilical region
the autonomic nerve supply is derived from T10 and T11, the area that supplies the skin around the umbilicus
where does the right testicular (and ovarian) vein drain to
IVC
where does the left testicular (and ovarian) vein drain to
left renal vein
varicocele is more common in which testis
left
what are the 9 abdominal regions
epigastrium left and right hypochondrium peri-umbilical left and right lumbar/loin suprapubic left and right inguinal
at what stage gestation does the uterine fundus become palpable
12 weeks
the inguinal ligament is formed from the aponeurosis of which muscle
external oblique
which hormone allows the female pelvic ligaments to relax during childbirth
relaxin
why might the fundal height start to decrease from around 36 weeks gestation
the fetal head starts to descend into the pelvis
how does symphysiofundal height relate to gestation
gestation = symphysiofundal height +/- 3 cm
which two incisions can be used to access the pelvis
midline vertical
lower transverse
the midline vertical incision is made through which structure
give an advantage and disadvantage of this type of access
linea alba
relatively avascular to rapid, bloodless access is achieved and it can be easily extended
lack of vascularity means healing is difficult and there is increased risk of wound dehiscence and hernia formation
what type of surgery is a midline vertical incision more commonly used and why
gynaecological oncology operations
allows for wide surgical access
what are the benefits of a lower transverse incision over a midline incision
better cosmetic outcome
less pain
lower incidence of hernia formation
what are the disadvantages of lower transverse incision
access is slower
blood loss is greater
nerve injury is more frequent
what type of surgery is a lower transverse incision often used for
c-section
what structures are incised during a c-section
skin superficial fascia rectus sheath (rectus muscles are separated) parietal peritoneum visceral peritoneum uterus amniotic sac
how is risk of damage to the bladder rescued during c-section
the patient is catheterised to reduce the size of the bladder
what is the surface marking of the inferior epigastric artery
immediately medial to the deep inguinal ring at the midpoint of the inguinal ligament
the artery passes obliquely up the abdomen towards a point about 2-3 cm lateral to the umbilicus
blood supply to the uterus
uterine arteries, branches of the internal iliac
uterine arteries anastomose with ovarian arteries which tend to supply the fundus
what are likely sites of spread of ovarian cancer
GI tract
bladder
liver
spleen
which nodes are likely to be involved in lymphatic spread of ovarian cancer
pelvic nodes
para-aortic nodes
at which two sites does lymph from the pelvis converge
para-aortic or lumbar nodes
what is the cisterns chyli
convergence of the lumbar lymph trunks that continues as the thoracic duct
lymph drainage of rectum
sacral and internal iliac
lymph drainage of anal canal
internal iliac (lower canal to superficial inguinal)
lymph drainage of bladder
internal and external iliac
lymph drainage of prostate and proximal urethra
internal iliac
lymph drainage of distal, penile urethra, penis and clitoris
superficial inguinal
lymph drainage of testis and ovaries
para-aortic
lymph drainage of uterine tube, uterine fundus and upper uterine body
para-aortic
lymph drainage of lower uterus, cervix and proximal vagina
internal and external iliac and sacral
lymph drainage of distal vagina and vulva
superficial inguinal
nerve supply of detrusor muscle
parasympathetics derived from the pelvic splanchnic nerves (s2,3,4)
nerve supply to urethral smooth muscle
sympathetic nerves derived from the spinal cord at T10 to L2
descends to bladder via the hypogastric nerves
nerve supply of pelvic floor
pudendal nerve S2,3,4
what sensation maintains the micturition reflex and which nerve senses it
sensation of urine in the urethra is sensed by the pudendal nerve
which surfaces of the bladder are covered by peritoneum
posterior and superior
which structures are given the collective name ‘vulva’
female urogenital triangle structures mons pubis labia minora and majora vestibule vaginal orifice orifices of the vestibular glands clitoris
what type of epithelium lines the vagina
stratified squamous
blood suupply to the vagina and urethra
variable branches from the uterine, vaginal and internal pudendal arteries
venous drainage of the urethra and vagina
vaginal plexus, draining to the internal iliac veins
structures supporting the cervix and upper vagina
uterosacral, transverse cervical and pubocervical ligaments
structures supporting the middle vagina
pelvic fascia
structures supporting the lower vagina
levator ani muscles and perineal body
‘double fold of peritoneum extending laterally from uterus to the pelvic side wall’
broad ligament
attachments of the transverse cervical ligaments
cervix and upper to vagina to the lateral walls of the pelvis
loss of support of the cervix and upper vagina results in…
uterine and vaginal vault prolapse
loss of support of the middle vagina results in…
cystocele and rectocele
loss of support of the low vagina results in…
stress urinary incontinence
what are the 3 parts of levator ani
puborectalis
pubococcygeus
iliococcygeus
what factors contribute to damage to pelvic floor supports
increase intra-abdominal pressure (obesity, chronic cough, constipation, intra-abdominal mass)
pelvic floor muscle trauma and denervation (obstetric trauma, pelvic fracture or surgery, congenital)
connective tissue disorder (age related, oestrogen deficiency)
attachments of coccygeus
ischial spine and inferior end of sacrum and coccyx
attachments of puborectalis
body of pubis and perineal body
attachments of pubococcygeus
pubic bone, tendinous arch of obturator fascia
vagina, perineal body, rectum and coccyx
attachments of iliococcygeus
ischial spine and perineal body/coccyx
why is puborectalis involved in maintaining faecal continence
it creates a sling around the rectum, creating an angle between the rectum and canal
nerve supply of elevator ani
nerve to levator ani (S4)
branches of pudendal nerve (S2,3,4)
which vessels pass through the obturator foramen
obturator artery
obturator vein
obturator nerve
