Perineum and Spaces Flashcards
what is os coxae formed from?
fusion of 3 paired bones and sacrum:
ilium
pubis
ischium
ilium
broad ala “wing”
- body forms upper 2/5ths of acetabulum
- posteriorly ilium articulates with sacrum
Ischium
- body forms posterior-inferior 2/5ths of acetabulum
- short superior ramus and inferior ramus forms the obturator foramen
- rami articulate with the pubis
Pubis
- consists of a short body
- superior and inferior rami (superior rami forms the anterior 1/5th of acetabulum)
Pubis symphysis
- fibrocartilaginous disc that links the two pubis bones
- classically it is the only site of mvmt in the pelvis, especially during pregnancy
sacroiliac joints
synovial joint between sacrum and ilium
- reinforced by anterior, posterior and interosseous sacroiliac ligaments
- additional reinforcement comes from sacrotuberous ligament: which runs from sacrum to the pubic tuberosity
- Mvmt: primarily a gliding motion, but can be rotary: interosseous sacroiliac and sacrotuberous ligaments resist rotary motion
sacrotuberous ligament
sacrum to ischial tuberosity
sacrospinous ligament
from sacrum/coccyx to ischial spine
lumbosacral joint
LV5/SV1 fibrocartilaginous joint (like intervertebral joints)
iliolumbar ligament
bipartite ligament
spans from transverse process LV5 to iliac crest
position of pelvis in normal erect position
- normally tips at 50-60 degrees from the horizontal
- base of sacrum is 4 inches higher than the symphysis
- ASIS and the symphysis pubis lie in the same vertical plane
gynecoid
most common female pelvis
- slightly oval-shaped pelvic inlet, the most circular
platypelloid
least common in both sexes
- exaggerated transverse inlet diameter
“flat” - provides greatest size of pelvic inlet
true conjugate
from sacrovertebral angle to superior margin of the symphysis
also called “anterior-posterior diameter”
diagonal conjugate
similar to true conjugate, however measures from the sacrovertebral angle to the inferior margin of the symphysis
- relates more to the pelvic outlet
transverse diameter
greatest width of the pelvic brim
coccygeus m.
O: ischial spine I:coccyx and lower sacrum n: S4,5 ventral rami A: supports pelvic viscera *** most posterior muscle of pelvic diaphragm.
terminal line
“pelvic brim”- divides pelvis into 2 portions:
- major (false) pelvis: above line
- minor (true) pelvis: below line
- the plane of the line is the superior aperture: pelvic inlet
- the inferior aperture/irregular lower border is the pelvic outlet
sexual dimorphism of pelvis
female pelvis:
- shallower major and minor pelvis
- anterior iliac crests tend to evert
- greater diameter of minor pelvis
- everted sciatic tubers
- broader sacrum with less curve
- superior aperture more oval
- subpubic angle is greater
android
- most common male pelvis (2nd most common in females)
- heart shaped pelvic inlet
anthropoid
- 2nd most common male pelvis (third most common in females)
- exagerated (tall) anterior/posterior inlet
two best shapes for birthing?
gynecoid and platypelloid
oblique diameter
from sacroiliac articulation of one side to iliopectineal (iliopubic) eminence of other side
diameters of superior aperture?
true conjugate
diagonal conjugate
transverse and oblique diameter
broad ligament
ligament found only in females, reaches across pelvis and is folded over uterus
diameters of the inferior aperture?
- transverse: between the inner surfaces of the ischial tuberosity
- anterior sagittal - from transverse diameter to the symphysis
- posterior sagittal: from transverse diameter to the sacrococcygeal junction
obturator internus muscle
- covers obturator foramen O: inner surface of obturator membrane I: greater trochanter of femur N: n. to obturator internus A: external rotation of thigh
- note: leaves the pelvis as a tendon that passes around the margin of the lesser sciatic notch
- covered by a heavy fascia called the obturator fascia from which levator ani muscle arises
boundaries of anal triangle?
anterior: posterior edge or urogenital diaphragm
posterior: boundaries of perineum (coccyx and caudal sacrum)
lateral: ischiopubic rami and obturator internus m. below
superior: roof of triangle is formed by interior aspect of pelvic diaphragm
inferior: skin and superficial fascia of perineum
pelvic diaphragm
supports pelvic viscera
- perineum below pelvic floor
- incomplete to allow passage of urethra and vagina
contains Levator ani m. and coccygeus m.
urogenital diaphragm
supports midline structures such as urethra, vagina and prostrate
three parts of levator ani muscle?
- iliococcygeus
- pubococcygeus
- puborectalis
all innervated by perineal branches of S3,4
action is to support pelvic viscera
pubococcygeus m.
O: pubis
I: coccyx
N: Perineal branches S3,4
a: supports pelvic viscera
middle muscle
iliococcygeus m.
O: arcus tendineus
I: coccyx
N: perineal branches of S3,4
A: supports pelvic viscera
*** most posterior muscle, just above coccygeus muscle
puborectalis m.
O: pubis I: puborectalis muscle from opposite side on posterior side of rectum N: perineal branches of S3,4 *** maintains anal rectal junction * most anterior muscle
coccygeus m.
O: ischial spine I:coccyx and lower sacrum n: S4,5 ventral rami A: supports pelvic viscera *** most posterior muscle of pelvic diaphragm.
pelvic peritoneum
- does not contact floor and walls of pelvis
- draped over superior aspects of pelvic structures and forms distinctive folds and pouches
- rectouterine/vesicouterine pouch in females
- rectovesical pouch in males
retrovesicle pouch
- pouch formed in males between rectum and the bladder
moving external to internal in the perineum…
skin superficial fascia Camper’s fascia Colle’s (Scarpa’s) fascia sup. perineal space (& contents) perineal membrane deep perineal space (& contents) sup. fascia of UG diaphragm ischioanal fossa pelvic diaphragm (levator ani m.) extraperitoneal CT peritoneum peritoneal space in pelvis
broad ligament
ligament found only in females, reaches across pelvis and is folded over uterus
what does anal triangle contain?
external anal sphincter
internal pudendal vessels:
- inferior rectal aa.
- perineal aa.
- deep and dorsal aa. of the penis/clitoris
nerves:
- pudendal n (S2-4): inferior rectal nn, perineal nn, dorsal n. to penis
- perineal branch of S4
divisions of perineum?
line connecting the ischail tuberosities:
- anal triangle
- urogenital triangle
boundaries of anal triangle?
anterior: posterior edge or urogenital diaphragm
posterior: boundaries of perineum (coccyx and caudal sacrum)
lateral: ischiopubic rami and obturator internus m. below
superior: roof of triangle is formed by interior aspect of pelvic diaphragm
inferior: skin and superficial fascia of perineum
urogenital diaphragm
stretches anteriorly between the two ischiopubic rami creating the UG and anal regions of the perineum
- made of sphincter urethrae (urethrovaginalis in females), compressor urethrae and deep transverse perineal m.
sphincter urethrae m.
called urethrovaginalis m. in females
surrounds membranoud urethrae
compressor urethrae m.
extends laterally from sphincter
deep transverse m.
posterior to sphincter urethrae m.
transverse perineal ligament
where fascia on superior and inferior surfaces of muscles of urogenital diaphragm fuse
- anteriorly does not extend to pubis, the deep dorsal v. or penis and the clitoris of the female enter through this gap.
superior fascia of UG diaphragm
from transversalis fascia
inferior fascia of UG diaphragm
known as perineal membrane
superficial perineal space
deep to skin, inferior to perineal membrane Colle’s fascia
Components of sexual apparatus:
- erectile bodies
- musculature
- vessels
- nerves
deep perineal space
space between inferior and superior fascia
- contains muscles of UG diaphragm, vessels and nerves
moving external to internal in the perineum…
skin superficial fascia Camper’s fascia Colle’s (Scarpa’s) fascia sup. perineal space (& contents) perineal membrane deep perineal space (& contents) sup. fascia of UG diaphragm ischioanal fossa pelvic diaphragm (levator ani m.) extraperitoneal CT peritoneum peritoneal space in pelvis
Ischioanal fossa
- fossa is filled with adipose tissues
- Boundaries:
superior: levator ani and pelvic diaphragm
inferior: skin of perineum
Posterior: right and left ischioanal fossa
anterior: components of external anal sphincter and UG diaphragm fuse to prevent communication
–. anterior recesses: extend anteriorly between the levator ani and UG diaphragm
what does anal triangle contain?
external anal sphincter
internal pudendal vessels:
- inferior rectal aa.
- perineal aa.
- deep and dorsal aa. of the penis/clitoris
nerves:
- pudendal n (S2-4): inferior rectal nn, perineal nn, dorsal n. to penis
- perineal branch of S4
external anal sphincter
- voluntary muscle surrounding the anal canal
- divided into superificial, subcutaneous and deep
internal pudendal vessels
branch of the internal iliac
leaves the pelvis through the greater sciatic foramen
- crosses the ischial spine and passes through the lesser sciatic foramen jin the pudendal canal
pudendal canal
fascial canal created by the splitting of the obturator fascia
inferior rectal aa
first branch of pudendal vessel after entering the pudendal canal
supplies the sphincter, anal canal and skin of anus
perineal aa.
arise near the posterior edge of the UG diaphragm
- branches from transverse perineal aa. and posterior scrotal (labial aa.)
deep and dorsal aa. of the penis (clitoris)
terminal branches of the internal pudendal aa.
run superior to the UG diaphragm
pudendal n.
S2-4 follows same course as the internal pudendal aa. branches are: inferior rectal nn. perineal nn. dorsal n. of the penis
perineal branch of S4
cutaneous distribution to the skin of the posterior anal triangle
- may contribute to innervate external sphincter
- innervates lateral most aspect of anal and UG regions down onto medial thigh
boundaries of male UG triangle
anterior: pubis
lateral: ischiopubic rami
posterior: dorsal edge of UG diaphragm
superior: pubo-coccygeal portion of levator ani muscles
UG diaphragm
- voluntary muscular sheet between ischiopubic rami: from the pubis to ischial tuberosities:
- sphincter urethrae m. forms anterior portion and deep transverse perineal m. forms posterior portion
- does not extend anteriorly to pubis, but rather anterior gap is filled with transverse perineal ligament where the deep dorsal vein to penis travels through
- bulbourethral glands and muscles of diaphragm are sandwiched between faschial sheath layers to form the deep perineal space.
superficial perineal fascia
- Colle’s fascia
- most superficial fascia layer of UG diaphragm
- forms superficial penile fascia = Darto’s fascia (superficial fascia of scrotum )
Darto’s fascia
superficial fascia of scrotum
formed from Colle’s fascia
deep perineal fascia
- intimately surrounds the cavernous bodies
- forms deep penile fascia (Buck’s fascia)
creates potential space b/w superficial and deep penile fascia
Buck’s fascia
deep fascia of penis
transverse perineal a.
supplies are of central tendon
- comes from perineal a.
posterior scrotal (labial) a.
runs into the scrotum (labia) in the superficial perineal space
- comes from perineal a.
artery of the bulb
branch from internal pudendal a.
- supplies bulbourethra gland and bulb of corpus spongiosum
urethral a.
branch of internal pudendal a.
- enters spongy body to supply urethra dn the glans
deep arter of penis
terminal branch of internal pudendal a. that supplies cavernous body
dorsal artery of the penis
terminal branch of internal pudendal a. that supplies dorsal surface of penis
deep dorsal vein of penis/clitoris
single large midline v. deep to deep fascia
perineal branches of the pudendal nerve?
- posterior scrotal (labial) n.
- deep branches
- dorsal n. of the penis or clitoris
