Functional Anatomy of the Pelvis

Question 1

what type of joint are the SI joints

Answer 1

atypical joint surfaces

Diarthrosis- true synovial joint with joint cavity, synovial fluid and joint capsule

Question 2

how many joints make up the pelvis

Answer 2

3

Question 3

what type of joint SI

Answer 3

diarthrosis

Question 4

Is the SI a synovial joint

Answer 4

yes

Question 5

what type of cartilage is associated with the pubic symphasis

Answer 5

fibrocartilagenous

Question 6

what level is the upper half of the SI joint

Answer 6

S1

Question 7

what level is the lower half of the SI Joint

Answer 7

S2-3

Question 8

what type of cartilage is the sacral surface made of and what color is it?

Answer 8

hyaline cartilage and Blue

Question 9

what type of cartilage is the iliac surface made of and what color

Answer 9

fibrocartilage and yellow

Question 10

is the groove for the sacral surface convex or concave

Answer 10

concave

Question 11

iliac surface concave or convex?

Answer 11

convex

Question 12

what is the point of intrinsic ligaments at the SI joint

Answer 12

limit movement and provide support

Question 13

the posterior sacral ligament is composed of two parts, an interosseos and dorsal ligament. what are their function?

Answer 13

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

Question 14

T/F the anterior sacroiliac ligament is thin; thickening of the anterior joint capsule

Answer 14

T

Question 15

T/F joint capsule is well developed posteriorly

Answer 15

F, well developed anterior not posteriorly

Question 16

what two ligaments make up the extrinsic ligaments

Answer 16

sacrotuberous and sacospinous ligaments

Question 17

where is the sacrotuberous ligament

Answer 17

inferior portion of the sacrum to the ischial tuberosity. limits POSTERIOR movement of SACRAL APEX

Question 18

where is the sacrospinous ligament

Answer 18

inferior lateral edge of the sacrum and the upper edge of the coccyx to the ischial spine.
limits POSTERIOR movement of the SACRAL APEX

Question 19

what kind of joint is the pubic symphysis

Answer 19

amphiarthrosis, interpubic fibrocartilaginous disc

Question 20

what muscles directly cross the SI joint?

Answer 20

none

Question 21

what muscles may load the joint

Answer 21

erector spinae
QL
Psoas
iliacus
piriformis
gluteals

Question 22

what is the keystone effect

Answer 22

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

Question 23

what is the self locking mechanism

Answer 23

[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)

Question 24

what are the dynamics of the pelvis

Answer 24

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