Organization of the Pelvis and Perineum Flashcards
What space is located below the pelvic brim and is where the fetus can get caught between bony landmarks?
true pelvis
The (…) is situated above the pelvic brim, and bounded on either side by the ilium, while in the front it is incomplete
greater pelvis (false pelvis; pelvis major)
The (…) is situated below and behind the pelvic brim, and is divided into an inlet and outlet part
lesser pelvis (true pelvis; pelvis minor)
What is the anterior boundary of the pelvic inlet?
symphysis pubis (pubic symphysis)
What is the posterior boundary of the pelvic inlet?
- promontory of sacrum
- ala of sacrum
What is the lateral boundary of the pelvic inlet?
iliopectineal (arcuate) lines
What are the boundaries of the pelvic inlet?
- anteriorly: pubic symphysis
- posteriorly: promontory of sacrum; ala of sacrum
- laterally: iliopectineal (arcuate) line
What is the anterior boundary of the pelvic outlet?
symphysis pubis (pubic symphysis)
What is the posterior boundary of the pelvic outlet?
coccyx
What is the anterolateral boundary of the pelvic outlet?
- ischiopubic ramus
- ischial tuberosities
What is the posterolateral boundary of the pelvic outlet?
sacrotuberous ligament
What are the boundaries of the pelvic outlet?
- anteriorly: pubic symphysis
- posteriorly: coccyx
- anterolaterally: ischiopubic ramus; ischial tuberosities
- posterolaterally: sacrotuberous ligament
When looking from above, are you viewing the pelvic inlet or outlet?
pelvic inlet
When looking from below, such as in childbirth, are you viewing the pelvic inlet or outlet?
pelvic outlet
The pelvic inlet (superior pelvic aperture) is bounded by the (…)
linea terminalis of the pelvis
What forms the linea terminalis?
- pubic symphysis anteriorly
- posterior border of pubic crest
- pecten pubis (continuation of pubic ramus)
- arcuate line of ilium
- anterior board of ala of sacrum
- sacral promontory
What is important in females and childbirth (labor and delivery)?
the true pelvis
The (…) is in a steep oblique plane, which pushes the axis of the pelvis to be curved
pelvic inlet
What connects the vertebral column to the femurs?
the pelvic girdle
What does this describe:
- transfers weight from axial skeleton to lower appendicular skeleton
- withstand compression
- house and protect pelvic viscera
pelvic girdle
What are the 3 bones of the pelvic girdle?
- right hip bone
- left hip bone
- sacrum
The right and left hip bones are comprised of 3 separate bones, the (…), that fuse during puberty
- ischium
- ilium
- pubis
The hip bones are connected via the (…)
pubic symphysis
The hip bones and sacrum are connected via the (…), which is the posterior connection to the axial/appendicular skeleton
sacro-iliac joints
The sacrum is formed by the fusion of (…) sacral vertebrae
5
What forms the superior, posterior, and anterior part of the acetabulum?
- superior: body of ilium
- posterior: body of ischium
- anterior: superior pubic ramus
What type of joint is the hip joint and what is that area called?
- ball and socket joint
- called the acetabulum (not fossa)
The pubic arch is formed by (…)
the ischiopubic rami and the pubic symphysis
What is the distance between ischial tuberosities called?
subpubic angle
What is the general difference in the bony pelvis between males and females?
males: thick and heavy
females: thin and light
What is the difference in the pelvic inlet between males and females?
males: heart-shaped
females: oval
What is the difference in the pelvic outlet between males and females?
males: small
females: large
What is the difference in the pubic arch and subpubic angle between males and females?
males: narrow (<70°)
females: wide (>80°)
What is the difference in the greater pelvis (pelvis major) between males and females?
males: deep
females: shallow
What is the difference in the lesser pelvis (pelvis minor) between males and females?
males: narrow and deep
females: wide and shallow
What is the difference in the obturator foramen between males and females?
males: round
females: oval
What is the difference in the acetabulum between males and females?
males: large
females: small
What divides the true and false pelvis?
pelvic inlet
What is the greater (false) pelvis bounded by?
- anterior: abdominal wall
- posterior: L5/S1 vertebrae
- lateral: ala of ilium
What is the lesser (true) pelvis bounded by?
pelvic surfaces of the hip bones, sacrum, and coccyx
The (…) is found superior to the pelvic inlet; the (…) is found between pelvic inlet and outlet
- greater (false) pelvis
- lesser (true) pelvis
What does the lesser pelvis house?
pelvic viscera
What is the inferior extent of the lesser pelvis?
pelvic diaphragm
What are the primary joints of the pelvis?
- sacroiliac joint
- pubic symphysis
- lumbosacral joint
- sacrococcygeal joint
What are the three ligaments of the sacroiliac joint?
- anterior sacroiliac ligament
- interosseous sacroiliac ligament
- posterior sacroiliac ligament
What ligament is formed on the anterior capsule of the sacroiliac joint by the articulation between the auricle surfaces of the ilium and sacrum and is considered a synovial joint?
anterior sacroiliac ligament
What is formed of the posterior portion of the sacroiliac joint by the articulation of the tuberosities of the ilium and sacrum and is considered a syndesmosis joint?
posterior sacroiliac ligament
What ligament is responsible for transfer of weight of the upper body to the ilium and then the femurs during standing?
interosseus sacroiliac ligament
What does symphysis mean?
not a lot of movement, pretty fixed
What are the pelvic ligaments that stabilize the pelvic joints?
- pubic ligaments
- sacrococcygeal ligaments
- sacroiliac ligaments (anterior, posterior, interosseus)
- sacrotuberous ligament
- sacrospinous ligament
What ligament(s) resists the inferior sacrum being rotated superiorly?
the sacrotuberous and sacrospinous ligaments
What provides an exit from the pelvic cavity?
- greater sciatic foramen
- lesser sciatic foramen
- obturator canal
What ligament attaches the sacrum to the ischial tuberosity?
sacrotuberous ligament
What ligament attaches the sacrum to the ischial spine?
sacrospinous ligament
The sacrotuberous ligament is a strong ligament that forms the (…); the sacrospinous ligament is a strong ligament that forms the (…)
- lesser sciatic foramen
- greater sciatic foramen
What ligament provides so support to the pelvis?
inguinal ligament
Which ligament is longer, the sacrotuberous or sacrospinous ligament?
the sacrotuberous ligament
What forms the anterior, posterior, lateral, superior, and inferior walls of the pelvic cavity?
- anterior: pubic rami, pubic symphysis
- posterior: sacrum, coccyx, piriformis m
- lateral: obturator internus m
- superior(roof): open to ‘abdominal cavity’
- inferior(floor): pelvic diaphragm (levator ani + coccygeus m)
The obturator hole is blocked by the (…) except for a small hole, the (…)
- obturator internus m
- obturator canal
What are the muscles of the pelvic diaphragm?
- levator ani
- coccygeus m
What muscles are included in the levator ani group?
- iliococcygeus m
- pubococcygeus m
- puborectalis m
What are the attachments for the levator ani muscles?
- anterior: pubis
- anterolateral: tendinous arch
- posterior: ischial spine, anococcygeal body, perineal body, walls of pelvic organs
What are the actions of the pelvic diaphragm muscles?
- support pelvic viscera
- raise and lower pelvic floor, aids in defecation and urination
What are the muscles, from anterior to posterior that run through pelvic diaphragm?
- puborectalis m
- pubococcygeus m
- iliococcygeus m
- obturator fascia
- piriformis m
- coccygeus m
- obturator internus m
- tendinous arch
What muscles attach to the greater trochanter of the femur?
- obturator internus
- piriformis
What innervates the obturator internus?
nerve to obturator internus
What innervates the piriformis m?
anterior rami of S1-S2
What innervates the levator ani muscles?
- anterior rami of S3-S4
- perineal nerve
What innervates the coccygeus muscle?
anterior rami of S4-S5
What muscles rotate extended thigh laterally and abducts flexed thigh at hip?
- obturator internus
- piriformis m (also stabilizes hip joint)
What supports pelvic viscera and raises pelvic floor?
levator ani
What supports pelvic viscera and draws coccyx forward?
coccygeus
What muscle is more important and bigger than the obturator internus?
piriformis
All pelvic viscera are subperitoneal except for the (…) which are intraperitoneal
- uterine tubes
The (…) is not firmly bound to the suprapubic crest, allowing the (…) to expand between the peritoneum and anterior abdominal wall as it fills
- peritoneum
- bladder
The (…) is connective tissue that occupies the space between the membranous peritoneum and the muscular pelvic walls and floor not occupied by the pelvic organs
pelvic fascia