Joints and articulations of the pelvis Flashcards
What are the articulations of the pelvis?
pubic symphysis
sacroiliac joint
What type of joint is the pubic symphysis?
Non-synovial, amphiarthroidal joint.
Bony surfaces covered with a thin layer of hyaline cartilage. with a thicker fibrocartilage in between
What stabilizes the pubic symphysis?
superior and inferior pubic ligaments
What type of joint is the sacroiliac joint?
are true synovial joints
How does the sacroiliac joint start out?
L-shaped joint surfaces start out relatively flat but become molded to each other, with distinct elevations and depressions, as we age.
What is the symmetry in both left and right sacroiliac joints?
joint shapes vary considerably among individuals, but are often similar from left to right in a single individual.
What does assynnetry of the right and left sacroiliac joint may lead to?
sacroiliac joint disfunction (SJD
what s rotation of the sacroiliac joint?
nutation
What type of mobility does the sacroiliac joint have?
slightly mobile, allowing very limited translation and somewhat more rotation—just a few degrees
What does the posterior rotation of the sacroiliac joint do?
carries the promontory posteriorly and the coccyx anteriorly,
What does the posterior rotation of the sacroiliac joint do to the diameters of the pelvic inlet & outlet?
increases the diameter of the pelvic inlet but decreases the diameter of the pelvic outlet.
baby’s head engages pelvis
What does anterior rotation of the sacroiliac joint does?
carries the promontory anteriorly and the coccyx posteriorly
What does the anterior rotation of the sacroiliac joint do to the diameters of the pelvic inlet & outlet?
decreases the diameter of the pelvic inlet but increases the diameter of the pelvic outlet.
baby’s head crowns
Where is the coccyx from the point of rotation?
farther from the axis of rotation than the promontory. Hence it is more mobile (also because of movement between sacrum and coccyx). This is useful, because at its widest, the pelvic outlet is quite a bit smaller than the pelvic inlet at its narrowest!
What is the function of relaxin?
During pregnancy, the hormone relaxin causes the ligaments of the sacroiliac joint and pubic symphysis to loosen, allowing extra mobility.
