Introduction to the Sacrum Flashcards
At what level of the sacrum is the inferior lateral angle?
at S4 & S5
Name some sacral anterior anatomic landmars
Sacral base
Sacral Promontory
Sacral Apex
What is the coccyx?
the lowest part of the spinal column
consists of 4 vertebra
What separates adjacent sacral segments?
epiphyseal plates that fuse after puberty
Bony articulations of the sacrum
articulates w/ 5th lumbar vertebra superiorly
articulates w/ coccyx inferiorly
Sacral Joints
Right SI joint
Left SI joint
L5-S1 intervertebral disc
Sacrococcygeal joint
Considerations for SI joint after puberty
in males, SIJ ligaments are well-developed & strong
in females, SIJ ligaments are less developed
Considerations for SI joint in 2nd decade of life
ridge develops along iliac surface that interdigitates w/ depression on sacral side to add stability & limits mobility
Considerations for SI joint in 3rd decade of life
crescent shape ridge is more pronounced & decreases ROM
some degenerative changes occur on iliac side in males
Considerations for SI joint in 4th & 5th decades of life
in males, degenerative changes begin on sacral side
SI joint characteristics
L or C shaped with shorter upper arm & longer lower arm
Which direction does the apex point?
points anteriorly
What type of joint is the SI joint?
diarthrodial joint b/c contains synovial fluid & matching articular surfaces
1 side is hyaline cartilage & other side is fibrocartilage
Sacral surface of SI joint
smooth, hyaline cartilage, decreases in width inferiorly & wedged between 2 ilia
Iliac surface of SI joint
smooth anteriorly, is fibrous on posterior side (gives rise to interosseous ligaments), fibrocartilage
Posterior Sacroiliac Ligament
from 3rd & 4th sacral segments & ascents to PSIS & posterior end of iliac crest
thicker
Anterior Sacroiliac Ligament
connects 3rd sacral segment to lateral side of pre-auricular surface
blends w/ iliolumbar ligaments
Interosseous Sacroiliac Ligament
major bond between the bones, filling irregular space
covered posteriorly by posterior sacroiliac ligament