Pelvis and Perineum Flashcards
What are the functions of the bony pelvis?
- Protect the abdominal and pelvic viscera
- Transfers body weight
- Withstands compression
- Serves as attachment point for muscles
When do the ilium, ischium and pubis fuse?
puberty
Review bony landmarks of pelvis
pg. 1
What is the fibrocartilage connection connecting pubis bones called?
pubic symphysis
What is the pubic arched formed by?
inferior pubic rami and ischial rami from both sides
T/F: ASIS and pubic symphysis are in the same horizontal plane
False, they re in the same vertical plane
Which structure is open to the abdominal cavity?
pelvic inlet
What does the pelvic brim consist of?
sacral promontory and ala, ilial arcuate line, superior pubic ramus, and pubic symphysis
How is the pelvic outlet closed off?
by the funnel-shaped pelvic diaphragm
What is the pelvic outlet bounded by?
pubic arch, ischial tuberosities, sacrotuberous lig., tip of coccyx
Which pelvis (greater or lesser) is also known as the false pelvis, and which is the true pelvis?
greater = false lesser = true
Which pelvis (greater or lesser) contains some abdominal contents?
greater/false
Which structure is contained between the pelvic inlet and pelvic outlet?
lesser pelvis
What are the differences between male and female pelvic bones?
Male = 60 degree subpubic angle, thicker, heavier, narrow/deep lesser pelvis
Female= 90 degree subpubic angle, wide/shallow and larger pelvic inlet/outet, round or oval pelvic inlet
Which type of compression causes fractures to pubic rami?
anteroposterior compression
Which type of compression causes fractures to acetabula and ilia?
lateral compression
Can a pelvic ligament cause a fracture?
yes, as it is torn away from the bone
What type of joint is located posteriorly between tuberosities of sacroiliac bones?
syndesmosis
What type of joint is located anteriorly between auricular surfaces of sacroiliac bones?
synovial joint
What ligament is the thin anterior part of capsule called?
anterior sacroiliac lig.
What are the features of the interosseous sacroiliac lig.?
broad, fibrous connections between tuberosities - primarily responsible for weight transfer
What direction are the fibers of the posterior sacroiliac lig. oriented?
obliquely, superolaterally
What are the functions of the sacrotuberous and sacrospinous ligaments?
- limit upward mvmt of inferior part of sacrum
- resist sacral rotational mvmt during periods of sudden weight gain
Which direction are the facet joints in the lumbosacral joint oriented?
posteromedially, which helps L5 from sliding anteriorly
Is the fibrocartilagenous disc of the pubic symphysis thicker in males or females?
females
How much (in %) does the pelvic diameter increase during parturition?
10-15%, change is in transverse axis and NOT A-P
What primarily closes the obturator foramen?
Obturator membrane
Which foramen does the obturator internus m. travel through to reach the greater trochanter?
lesser sciatic foramen
What is the action of the obturator internus?
lateral rotation, hold head of femur in acetabulum
Which foramen does the piriformis m. exit the pelvis by?
greater sciatic foramen
The nerves of the sacral plexus cross the _________ (internal or external) surface of this muscle
internal
What is the action of the piriformis m.?
lateral rotation and abduction, and holds femur in acetabulum
What muscle groups form the pelvic diaphragm?
levator ani mm. and coccygeus m.
What is the function of the levator ani m.?
forms a muscular sling to support abdominopelvic viscera and resists increases in intra-abdominal pressure
what is the action (not function) of the levator ani m.?
raises pelvic floor and compresses abdominopelvic contents
Which muscle forms the narrow medial part of levator ani mm. ?
puborectalis m.
What does the puborectalis m. form, surround, and create?
- forms a U-shaped sling around anorectal junction
- surrounds the urogenital hiatus
- creates the puborectal sling at anorectal junction- the anorectal flexure
What is the main intermediate part of the levator ani m.?
pubococcygeus m.
Which levator ani m. is thin and aponeurotic?
iliococcygeus m.
Which ligament does the coccygeus m. lie across?
pelvic surface of the sacrospinous lig.
What is the innervation of the coccygeus?
VPR of S4-S5
What are the differences between parietal and visceral pelvic fascia?
parietal = membranous overlying muscles visceral = adventitial ensheathing pelvic organs
What makes up the tendinous arch of pelvic fascia in males?
puboprostatic and sacrogenital ligs.
What makes up the tendinous arch of pelvic fascia in females?
pubovesical and uterosacral ligs.
What separates the pelvic cavity from the perineum?
pelvic diaphragm
What are the general borders of the perineum?
mons pubis (anteriorly) medial surfaces of proximal thigh (laterally) gluteal fold and intergluteal cleft (posteriorly)
Which anatomical triangle contains the external genitalia?
urogenital triangle
what covers the urogenital triangle, spanning the pubic arch?
perineal membrane
What structures perforate through the urogenital triangle?
urethra (in both sexes) and the vagina (in females)
What is the central point of the perineum called?
perineal body, post to vag and ant to anus
Which muscles attach to the perineal body?
- superficial transverse perineal m.
- deep transverse perineal m.
- external anal sphincter
- bulbospongiosus
How could damage to the perineal body affect females?
prolapse of the vagiinnnee
