How many bones are associated with the pelvic joint?
3; 2 SI joints and a pubic symphysis
what is the function of the pelvic joint?
same as a typical vertebral functional unit
probably the least understood and most controversial function of any area in the musculoskeletal system
what kind of joint is the pelvis?
mobile synovial
what is the importance of the SI joint being a mobile synovial joint?
statics and dynamics of posture and gait
provide support for the trunk, guide movement and help absorb the compressive forces associated with locomotion and weight bearing
Which joint is often ignored by other health care practitioners as an insignificant feature of musculoskeletal problems?
pelvis
What do the contours of the pelvis develop into?
interlocking elevations and depressions that produce a keystone effect of the sacrum
what does the keystone effect of the sacrum do?
effectively distributes axial compressive forces through the pelvic mechanism
describe where the forces of the lower extremities go
they divide and head up toward the spine and anteriorly toward the pubic symphysis
also downward forces of gravity on the spine split to both sides
what does the SI joint look like when you are first born?
at birth, the joints are underdeveloped, smooth and flat
after you start walking, what happens to the SI joint?
the joints begin to take on their adult characteristics
what happens during the teen years to the SI joint?
begin to roughen and develop their characteristic grooves and ridges
what happens in the latera years of a male pelvis?
they will have interarticular adhesions across the SIjoints and will have lost SI joint motions
what does ankylosing spondilitis do to the SI joint?
causes complete fusion of the joint
likes the anterior longitudinal ligament, SI joint involvement complaints of SI joint pain and less ability to flex and extend
if it is not treated, it could go throughout the whole spine
tends to affect people in their twenties
fairly common, radiographic:involvemtn of lumbar and SI joints
describe the features of a gynecoid pelvis
inlet: round
sacrosciatic notch: average size
sacrum: average
subpubic arch: inclination well curved
describe the features of an android pelvis
inlet: triangular
sacrosciatic notch: narrow
sacrum: forward
subpubic arch: inclination straight
posterior sacroiliac ligaments
sacrum to the iliac tuberostiy ad posterior superior iliac spine (PSIS)
continue laterally with the sacrotuberous ligament and medially with thoracolumbar fascia
sacrotuberous ligament
lower portion of the sacrum obliquely downward to the ischial tuberostiy
continues caudally with the tendon of the long head of the biceps femoris
anterior sacroiliac ligament
numerous bands from lateral edge of the sacrum to the auricular surface of the ilium
sacrospinous ligament
from the lower lateral edge of the sacrum and the upper edge of the coccyx to the ischial spine
describe the motions during locomotion of the SI joint
flex/extend in unison with the corresponding hip joint
movements of flexion/extension in one joint are mirrored by the opposite movement at the other joint
recent models have stressed the SI joint’s important role in what?
maintaining stability during the transfer of forces between the lower exremity and the spine
nutation
as the left innominate moves posteriorly/inferiorly, the left sacral base moves anteriorly/inferiorly
counter nutation
as the right innominate moves anteriorly/superiorly, the sacral base moves posteriorly/superiorly
Gyroscopic movements
The proposed axes of motion in the SI articulation
Figure 8 movement
what muscles are the SI joint crossed by?
NONE
What muscles contribute to the strength of the joint capsule and ligaments of the SI joint?
quadratus lumborum, erector spinae, gluteus maximus, gluteus minimus, piriformis, iliacus, latissimus dorsi
what so the muscles of the SI joint contain?
fibrous expansions that blend with the anteiror and posterior SI joint ligaments
when the pelvis goes anterior and superior, what plane of motion did it subluxate?
+X
when the pelvis goes posterior and inferior, what plane of motion did it subluxate?
-X
when the pelvis goes external, what plane of motion did it subluxate?
L: -Y
R:+Y
when the pelvis goes internal, what plane of motion did it subluxate?
L: +Y
R: -Y
if the sacrum listing is SAL, what is the orthogonal listing?
+Z
if the sacrum listing is SAR, what is the orthogonal listing?
-Z
if the sacral subluxation is base posterior, what is the orthogonal listing?
-X (extension)
if the sacral subluxation is apex posterior, what is the orthogonal listing?
+X (flexion)
if the sacral subluxation is P-L, what is the orthogonal listing?
+Y
if the sacral subluxation is P-R, what is the orthogonal listing?
-Y
describe apex posterior
flexion malposition
nutation
describe base posterior
extension malposition
counternutation
Ankylosing spondylitis likes which joint?
SI joint
What does ankylosing spondylitis do?
Completely fuses the joint, likes the ALL
tends to affect people in their 20s
What happens if ankylosing spondylitis is not treated?
Could go throughout the whole spine