The Sacrum and Coccyx
Superior articular processes of Sacrum
-Articulate with the inferior articular processes of L5 and form the lumbo-sacral junction -
Ala
-Broad, expanded portion of the upper sacral segment
Location of Sacrum
-Directly inferior to the lumbar spine -Between the 2 innominate bones, forming the posterior aspect of the pelvic cavity
Location of Coccyx
-Directly inferior to the sacrum -Most inferior portion of the spinal column
General Description of Sacrum
-Formed by the fusion of the five sacral vertebral segments into a curved, triangular bone.
Vertebral foramen
-Forms a descending tunnel called the sacral canal
Evaluation Criteria, AP Axial Sacrum
-No foreshortening -No overlapping by pubic bones -No rotation, as indicated by symmetric alae -Centered and seen in it's entirety -Tight collimation -No overlapping by fecal material
Anatomical characteristics of the Sacrum
-Only bony anatomy considered to be part of both the axial and appendicular skeleton -Shaped like an inverted triangle -Presents left and right borders which articulate with the innominate bones
Evaluation Criteria, AP obl. SI Joints
-Open sacroiliac joint space with minimal overlapping of the ilium and sacrum
Sacral foramina
-Provide passageways for the sacral nerves through both the anterior and posterior sides of the sacrum
Evaluation Criteria, AP Axial Coccyx
-Segments not superimposed -Short-scale contrast -No rotation -Centered and seen in it's entirety -Tight collimation
Evaluation Criteria, LAT Sacrum and Coccyx
-Short-scale contrast -Use of tight collimation and lead rubber absorber behing the sacrum -Closely superimposed posterior margins of the ischia and ilia
Breathing Instructions LAT Coccyx
-Suspend Respiration
Breathing Instuctions, LAT Sacrum
-Suspend on Expiration
Sacro-coccygeal articulation
-The superior articulating processes on the superior aspect of the coccyx articulates with the inferior segment of the sacrum
CR placement, AP Obl. SI Joints LPO/RPO
1" medial to ASIS
Film size, and Collimation, ALL Sacrum views
10X12 LW B, 8 by 8 collimation
Film size and Collimation, Obl. SI Joints
10X12 LW B, FFC
CR placement, LAT Coccyx
2" inferior, and 3 1/2" posterior to ASIS
CR placement, LAT Sacrum
3 1/2" posterior to ASIS
Number of Sacral Foramina
4 pairs of foramina
Film size, and Collimation, LAT Coccyx
8X10 LW B, 6 by 6 collimation
Film size, Collimation, and CR, AP Axial Coccyx
8X10 LW B, 6 by 6 collimation, Align MSP, 2" superior to symphysis pubis
CR placement, AP Axial Sacrum
Aligned to MSP, and 2" superior to symphysis pubis
