Lower borders of the lower 7 ribs (runs like hands in your pocket)
Insertion/Distal Attachment
Outer lip of the iliac crest; inguinal ligament; anterior layer of the rectus sheath
Action/Relevance
Unilateral: Rotates trunk to side opposite of contractionLaterally flexes trunk to same side of contraction Bilateral: Flexes the trunk4. Compresses the abdomen
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In other words, they are the muscles that give bodybuilders that upper body "V" look.