The transversus abdominis, so called for the direction of its fibers, is the innermost of the flat muscles of the abdomen, being placed immediately beneath the internal oblique muscle.
It arises, as fleshy fibers, from the lateral third of the inguinal ligament, from the anterior three-fourths of the inner lip of the iliac crest, from the inner surfaces of the cartilages of the lower six ribs, interdigitating with the diaphragm, and from the lumbodorsal fascia.
The muscle ends in front in a broad aponeurosis, the lower fibers of which curve downward and medialward, and are inserted, together with those of the internal oblique muscle, into the crest of the pubis and pectineal line, forming the inguinal aponeurotic falx. In layperson's terminology, the muscle ends in the middle line of a person's abdomen.
Throughout the rest of its extent the aponeurosis passes horizontally to the middle line, and is inserted into the linea alba; its upper three-fourths lie behind the rectus muscle and blend with the posterior lamella of the aponeurosis of the internal oblique; its lower fourth is in front of the rectus abdominis.
Without a stable spine, one aided by proper contraction of the TVA, the nervous system fails to recruit the muscles in the extremities efficiently, and functional movements cannot be properly performed. The transversus abdominis and the segmental stabilizers (e.g. the multifidi) of the spine are designed to work in tandem.
Popular culture and the pop fitness industry have largely overlooked the aesthetics of a strong TVA, probably because of the lack of economic incentive in doing so. While it is true that the TVA is vital to back and core (anatomy) health, the muscle also has the effect of pulling in what would otherwise be a protruding abdomen (hence its nickname, the “corset muscle”). Training the rectus abdominis muscles alone will not and can not give one a “flat” belly; this effect is achieved only through training the TVA. Thus to the extent that traditional abdominal exercises (e.g. crunches) or more advanced abdominal exercises (e.g. bicycle crunch) tend to “flatten” the belly, this is owed to the tangential training of the TVA inherent in such exercises. Recently the transversus abdominis has become the subject of debate between kinesiologists, strength trainers, and physical therapists. The two positions on the muscle are (1) that the muscle is effective and capable of bracing the human core during extremely heavy lifts and (2) that it is not.
Transabdominal ultrasound measurement of pelvic floor muscle activity when activated directly or via a transversus abdominis muscle contraction.
Nov 01, 2004; Design: Contraction of the transversus abdominus (TrA), pelvic floor muscles (PFM) and both muscle groups together (TrA...