Intro to Sacrum DSA Flashcards
Landmarks of the anterior sacrum?
Anterior Sacral Foramina
Sacral Promintory
Transverse lines
Sacral Apex
Base
Sacral Ala
Landmarks of the posterior Sacrum?
auricular surface of the SI joints.
spinous processes of S1-S5
Posterior Sacral Foramen.
Inferior Lateral Angle
Sacral canal (near the base) –> goes all the way to the sacral hiatus
What are the lines of the posterior sacrum?
`Median Sacral Crest
Intermediate Sacral Crest
Lateral Sacral Crest
what are the edges of the sacral hiatus called?
Sacral Comu
Coccyx has what muscular attachments?
Coccygeus M.,
Gluteus Maximus M.
Levator Ani
How is the sacrum formed?
what bones are part of the sacrum?
when does the arch/costal part fuse?
what about this and the rest of the sacrum?
when do the plates fuse and in what direction?
What about the dura, where is that at?
formed by the union of 5 modified vertebrae (35 ossification centers)
Costal elements, vertebral arch, Centrum, lateral epiphysis
bony arch + costal part between 2 and 5
they unite with the centrum at age 8.
epiphyseal plates fuse after puberty, beginning with lowest segments and working up.
the dura attaches at the OA/AA and it comes down through the whole spinal column and attaches at the posterior portion of the body of S2!
What are the bony articulations of the sacrum?
5th lumbar (superiorly)
coccyx (inferiorly)
Innominate bones (Auricular surface)
What are the joints of the sacrum?
Right and left SI joints
L5-S1 intervertebral disc
Sacrococcygeal joint.
After puberty, what happens to the SI joint in males? females?
2nd decade?
3rd decade? what about males?
4th decade? Males?
Males = well developed and strong
females = less developed allowing mobility for childbirth
second decade = crescent shaped ridge develops along the iliac surface that interdigitates with the depression on the sacral side.. adding stability and limiting mobility
the ridge becomes more pronounced decreasing ROM… males might have degenerative changes
males: degenerative changes on the sacral side.. also can see fibrous ankylosis that may further limit it.
Where is the SI joint located?
about at S2
Where is the apex of the SI joint?
what kind of joint is it?
at the anterior aspect, where the two “arms” meet up.
diarthrodial joint –> because synovial fluid and matching articular surfaces
it’s different than any other joint because it’s hyaline cartilage and the other part is fibrocartilage.
What’s to note about the iliac surface of the SI joint?
it’s fibrous posteriorly, giving rise to the interosseous ligaments
fibrocartilage
What are the ligaments of the SI joint?
posteriorly what does it blend with?
anteriorly what does it blend with?
posterior sacroiliac ligament –> inferior fibers from the 3rd and fourth sacral sacral segments, ascend to the PSIS and posterior end of the internal lip of the iliac crest.
STL and the thoracolumbar fascia.
Anterior Sacroiliac ligament –> connects the 3rd sacral segment to the lateral side of the pre-auricular sulcus.
blends with the iliolumbar ligament.
what’s thicker, anterior or posterior sacroiliac ligament?
posterior
Interosseous sacroiliac ligament?
major bond between the bones, filling the irregular space posterosuperior to the joint
these are the straps going from the SI joint to the sacrum posteriorly