Sacrum Flashcards
What is the typical number of segments that unite to form the adult sacrum?
5
What is the generic size of the first sacral vertebral body from the base view?
transversely broad
What is the generic shape of the first sacral vertebral body from the base view?
reniform or kidney-shaped
What characteristics of S1 vertebral body and pedicle are similar to L5?
- On base view, the S1 TVP and costal element originate from the vertebral body, pedicle, and lamina-pedicle junction to form the sacral ala.
- In addition, the vertebral body of S1 is more wedge-shaped on lateral view with a much greater anterior height than posterior height.
How many synovial joint surfaces are present at the S1 vertebral body?
none
What is the outline of the S1 vertebral foramen and the sacral spinal canal from the base view?
triangular
Which is the greatest diameter of the vertebral foramen of the sacrum?
transverse
What part of the PNS is present in the S1 vertebral foramen?
cauda equina
What forms the sacral ala?
- costal element: anterior 2/3
- true transverse process: posterior 1/3
What is the joint classification for the spongy bone-intervertebral disc articulation?
cartilaginous (amphiarthrosis) symphysis
What is the joint classification for the longitudinal lig. attachments?
fibrous (amphiarthrosis) syndesmosis
How many fibrous (amphiarthrosis) syndesmosis joint surfaces are present on the S1 vertebral body?
4
What fibrous (amphiarthrosis) syndesmosis joint surfaces are present on the S1 vertebral body?
- superior and inferior anterior longitudinal lig. attachment sites
- superior and inferior posterior longitudinal lig. attachment sites
How many joint surfaces are present on the vertebral body of S1?
5
How many cartilaginous (amphiarthrosis) symphysis joint surfaces on present on the S1 vertebral body?
1
What muscle may attach to the S1 vertebral body?
psoas major
What is the orientation of the pedicle of S1?
primarily posterior
At what location on S1 vertebral body will the pedicle attach?
to the upper third or half of the vertebral body
What surface feature is located at the upper margin of the pedicle?
superior vertebral notch
Which spinal nerve will be accommodated on the superior vertebral notch of S1?
L5 spinal nerve
Which spinal nerve will be accommodated on the inferior vertebral notch of S1?
S1 spinal nerve
What is the reported angulation of the S1 articular facets?
they lie vertically in the coronal plane
What is the joint classification for the S1 zygapophysis?
synovial plane (diarthrosis arthrodia)
How many zygapophyseal joints are present on the S1 vertebra?
2
What is the position of the sacral zygapophysis in children?
lies in the coronal plane
What is the position of the sacral zygapophysis in adults?
lies in the coronal plane for L5/S1
What is the orientation of the S1 superior articular facet?
- backward, upward, medial (BUM)
- typically concave
What is the name given to the projection on the S1 superior articular process?
mammillary process
What muscles will attach to the sacral mammillary processes?
multifidis
From anterior view, the intervertebral discs of sacrum will be replaced by what feature?
transverse ridges