I think its the Erector Spinae muscles that surround the spine. When these contract you get Bilateral extension of the spine, ie back bend. there fore the Rectus Abs need to softern and lengthen. Am I correct???
Rectus abdominus Internal and external obliques Transversus abdominus.
Rectus abdominis
rectus abdominus muscle
It provides an attachment point for the rectus abdominus muscle.
Rectus Abdominus
rectus abdominus
The rectus abdominus is a long, straplike muscle that connects the pubic bones to the rib and sternum.
Rectus abdominus
Transversus Abdominus & Rectus Abdominus
The antagonist muscle of the multifidus is the rectus abdominis. The rectus abdominis is responsible for flexing the lumbar spine, while the multifidus helps to extend and stabilize the spine.
This muscle lays beneath your Rectus Abdominus and it is one of the major muscles that stabilises your spine.
The external oblique muscles are situated on each side of the rectus abdominus. This muscle allows the trunks to be twisted or rotated.