The “core” or “core abdominals” are two buzz words found particularly in the fitness industry. However, the core abdominal muscles are more than the “six-pack abs” that are discussed in mainstream media.
The abdominals are made up of three “flat layers” and one “strap” portion.
The three flat layers make up the sides of the torso and with their fascia wrap around the spine. These include:
• transversus abdominis (innermost)
• internal oblique, and
• external oblique (outermost)
The strap portion that runs vertically, called the right and left rectus abdominis, is encased within the fascia/connective tissue of the flat layers.
The deepest layer of the abdominal muscles, or transversus abdominis, is the layer that is referred to as the core abdominals. The attachments of this muscle include the iliac crest, inguinal ligament, thoracolumbar fascia, costal cartilages 7-12, xyphoid process, linea alba, pubic crest, and pectin pubis. The muscle fibres of this layer run in horizontal plane (or in medical terms, a transverse plane). Due to the orientation of the muscle fibres, the actions of the core abdominals include compression of the ribs and viscera (like a girdle or corset), as well as thoracic, lumbar and pelvic stability.