SIDE STRAIN ANATOMYThe abdominal wall is composed primarily of three muscles
from exterior to interior they are:
• the external oblique
• the internal oblique and
• the transversus abdominis
They all comprise a muscular origin and a more tendinous or, more specifically, aponeurotic insertion
Anteriorly they attach to the rectus abdominis muscle
Posteriorly they attach to the quadratus lumborum muscle and
Inferiorly via aponeurosis to the inguinal ligament and pubis
Depending on the particular muscle, there are also attachments to the undersurface of the ribs below rib 9 and to the iliac blade
SIDE STRAIN INJURYSide strain injury is a tear predominantly involving the internal oblique muscle most commonly from the undersurface of rib 10 or 11 (red area on image)
A similar but different type of injury can be a tear from the iliac crest
Tears of the aponeurotic insertion are biomechanically different, see under the heading Athletic Pubalgia