Please kindly provide me with what these abbreviations in multifidus fascicles mean: SIPS in “MFtstL1SIPSPar” and which Ligament in “ MFtsL3LigamentPar”. Also, is there a difference between S1 and sacrum in “ MFmL3S1Par” and “ MFmL4SacrumPar” so that’s why they are named differently (though S1 is the same is sacrum anatomically).
The SIPS is short for Sacro Iliac Posterior Spine and refers to the insertion of the fascicle. In our model the sacrum is one segment and not divided in S1-S3 so the Sacrum/S1 naming refers to the same segment but different locations on it. The L3Ligament fascicle is named that way because it originates from L3 and inserts on the posterior sacro illiac ligament on the sacrum - so it is not a ligament but inserts at a location one.