Ach: Lower Abdominal Cavity I Flashcards
What forms the pelvic brim?
- sacral promontory and ala
- pectineal line
- symphysis pubis
What forms the false pelvis?
part of the abdominal cavity that supports abdominal organs
What forms the true pelvis?
- Pelvic inlet
- pelvic outlet (coccyx, ischial tuberosities, pubic arch)
- pelvic cavity (space between inlet and outlet)
What forms the sacrococcygeal joint?
cartilagenous intervertebral joint (S5-C1)
What forms the symphysis pubis?
fibrocartilagenous joint between bodies of two pubic bones
What forms the lumbosacral joint?
typical cartilagenous intervertebral joint between L5-S1
What forms the sacroiliac joint?
synovial joint between articular surfaces of ilium and sacrum
What is the interosseous sacroiliac ligament?
Suspends sacrum between two iliac bones
transfers weight from axial to appendicular skeleton
Resists forward rotation of the upper sacrum
What is the difference between the posterior and anterior sacroiliac ligaments?
Anterior = thin, not well defined
posterior= 2 parts, very strong
What forms the sacrotuberous ligament?
from the ischial tuberosity to lower sacrum and coccyx
What does hte sacrotuberous ligament do?
resists backward rotation of the lower sacrum
Where is the sacrospinous ligament?
It extends from the ischial spine to the lower sacrum and coccyx
What does the sacrospinous ligament do?
resists backward rotation of the lower sacrum
What is the difference between the pelvises of males and females?
M- heavy, thick, more prominent bone markings,
F- wider, shallower, larger superior and inferior pelvic apertures, ROUNDER and WIDER pubic arch
pelvic inlet is heart shaped in M but OVAL in F
Antrhopoid pelvis
ape like 23%
platypelloid pelvis
flat 2%
android pelvis
M 32%
gynecoid pelvis
F 43%
What can cause dystocia (difficult labor)?
deformities of the pelvis
What is the true conjugate diameter?
Sacral promontory to point just below the superior margin of the pubic symphysis (11 cm)
The shortest diameter through which the head must pass (radiographic films)
What is the diagonal conjugate?
sacral promontory to lower border of pubic symphysis (11.5 cm) (easily measured and assessed)
What is the obstetric conjugate?
sacral promontory to thickest part of pubic bone (10 cm)
What forms the pelvic walls?
- obturator internus
2. piriformis
What forms the pelvic floor? What does it support?
The pelvic diaphgram
supports the pelvic viscera
Where is the pelvic diaphragm located?
Stretches across the pelvis like a hammock
Suspended from the iliacus fascia
Divides the cavity into the pelvis above and the perineum below
What are the two divisions of the pelvic diaphgragm?
- levator ani (anterior)
2. coccygeus (posterior)
What are the actions of the pelvic diaphragm
Support pelvic floor and organs that pierce it
Resists outward thrust accompanying increases in intra-abdominal pressure (forced expiration and coughing)
Assists in defecation