Functional Anatomy of the Pelvis Flashcards
what type of joint are the SI joints
atypical joint surfaces
Diarthrosis- true synovial joint with joint cavity, synovial fluid and joint capsule
how many joints make up the pelvis
3
what type of joint SI
diarthrosis
Is the SI a synovial joint
yes
what type of cartilage is associated with the pubic symphasis
fibrocartilagenous
what level is the upper half of the SI joint
S1
what level is the lower half of the SI Joint
S2-3
what type of cartilage is the sacral surface made of and what color is it?
hyaline cartilage and Blue
what type of cartilage is the iliac surface made of and what color
fibrocartilage and yellow
is the groove for the sacral surface convex or concave
concave
iliac surface concave or convex?
convex
what is the point of intrinsic ligaments at the SI joint
limit movement and provide support
the posterior sacral ligament is composed of two parts, an interosseos and dorsal ligament. what are their function?
interosseos- massive major posterior stabilizer
Dorsal ligament- smaller, not as critical for stability, from sacrum to the PSIS and iliac tuberosity, limits nutation, dorsal rami run between interosseous and posterior sacroiliac ligaments
T/F the anterior sacroiliac ligament is thin; thickening of the anterior joint capsule
T
T/F joint capsule is well developed posteriorly
F, well developed anterior not posteriorly
what two ligaments make up the extrinsic ligaments
sacrotuberous and sacospinous ligaments
where is the sacrotuberous ligament
inferior portion of the sacrum to the ischial tuberosity. limits POSTERIOR movement of SACRAL APEX
where is the sacrospinous ligament
inferior lateral edge of the sacrum and the upper edge of the coccyx to the ischial spine.
limits POSTERIOR movement of the SACRAL APEX
what kind of joint is the pubic symphysis
amphiarthrosis, interpubic fibrocartilaginous disc
what muscles directly cross the SI joint?
none
what muscles may load the joint
erector spinae QL Psoas iliacus piriformis gluteals
what is the keystone effect
sacrum forms keystone of an arch suspended by strong sacroiliac ligaments
inferior displacement resisted by wedge shape of the sacrum
posterior displacement resisted by sacroiliac ligaments
anterior displacement resisted by sacroiliac ligaments and pubic symphysis
what is the self locking mechanism
[FORM CLOSURE]
wedge shape of sacrum, interlocking grooce (sacrum) and ridge (ilium), S shaped joint surfaces
[FORCE CLOSURE]
tension in muscles, ligaments, and thoracolumbar fascia aids in stabilizing the SI joints. (creates L to M pressure from the ilia to sacrum compressing SI joints) (clutch)
what are the dynamics of the pelvis
transmits forces between LE and axial skeleton.
Shock absorber- slides and pivots to absorb and adapt to forces generated between trunk and LE during locomotion.
decreases stress to lumbar spine and opposite SI joint
