Transversus abdominis muscle
Encyclopedia
The transversus abdominis muscle, also known as the transverse abdominus, transversalis muscle and transverse abdominal muscle, is a muscle layer of the anterior and lateral abdominal wall which is deep to (layered below) the internal oblique muscle. It is thought to be a major muscle of the functional core
of the human body, although some argue that due to its small cross-sectional area, it cannot generate the forces required to be a prime core stabilizer.
, 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.
and pectineal line
, forming the inguinal aponeurotic falx, also called the conjoint tendon. 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.
and the ilioinguinal nerve
.
, the aponeurosis of the Transversus abdominis or the outer end of the linea semicircularis and other slender slips are occasionally found. The nerves associated with the transverse abdominus are the intercostal, iliohypogastric, and the ilioinguinal.
. The TVA also (involuntarily) contracts during many lifts; it is the body's natural weight-lifting belt, stabilizing the spine and pelvis during lifting movements. It has been estimated that the contraction of the TVA and other muscles reduces the vertical pressure on the intervertebral discs by as much as 40%. Failure to engage the TVA during higher intensity lifts is dangerous and encourages injury to the spine. The TVA acts as a girdle or corset by creating hoop tension around the midsection.
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.
While it is true that the TVA is vital to back
and core
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 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.
Core (anatomy)
In anatomy, the core refers, in its most general of definitions, to the body minus the legs and arms. Functional movements are highly dependent on the core, and lack of core development can result in a predisposition to injury...
of the human body, although some argue that due to its small cross-sectional area, it cannot generate the forces required to be a prime core stabilizer.
Structure
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.Origin
It arises, as fleshy fibers, from the lateral third of the inguinal ligamentInguinal ligament
The inguinal ligament is a band running from the pubic tubercle to the anterior superior iliac spine. Its anatomy is very important for operating on hernia patients.-Anatomy:...
, 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.
Insertion
The muscle ends anteriorly in a broad aponeurosis, the lower fibers of which curve inferomedially (medially and downward), and are inserted, together with those of the internal oblique muscle, into the crest of the pubisPubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
and pectineal line
Pectineal line
On the posterior surface of the femur, the intermediate ridge or pectineal line is continued to the base of the lesser trochanter and gives attachment to the pectineus muscle....
, forming the inguinal aponeurotic falx, also called the conjoint tendon. 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
Linea alba
The linea alba is a fibrous structure that runs down the midline of the abdomen in humans and other vertebrates. The name means white line and the linea alba is indeed white, being composed mostly of collagen connective tissue....
; 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.
Layman's description
- The transverse abs run from our sides (lateral) to the front (anterior), its fibers running horizontally (transverse).
- The lateral beginnings of the muscle (origin) run from the front of the inside part of the hip bone http://education.yahoo.com/reference/gray/subjects/subject?id=57#p234 (anterior iliac crestIliac crest-External links: - "Superficial muscles of the gluteal region and posterior thigh." - "Anterior Abdominal Wall: Osteology and Surface Anatomy " - "The Back, Posterior View" * *...
and inguinal ligamentInguinal ligamentThe inguinal ligament is a band running from the pubic tubercle to the anterior superior iliac spine. Its anatomy is very important for operating on hernia patients.-Anatomy:...
) to the last rib of the rib cage. It also is connected to the diaphragm which helps with inhalation.
- The muscle runs transverse and is the deepest of the major abdominal muscles (the others being the rectus abdominis, and the internal and external obliques).
- It ends (the muscle insertion) by joining with the large vertical abdominal muscle in the middle (the linea albaLinea albaThe linea alba is a fibrous structure that runs down the midline of the abdomen in humans and other vertebrates. The name means white line and the linea alba is indeed white, being composed mostly of collagen connective tissue....
), where the fibers begin to curve downward and upward depending on what direction it has to go to meet the linea albaLinea albaThe linea alba is a fibrous structure that runs down the midline of the abdomen in humans and other vertebrates. The name means white line and the linea alba is indeed white, being composed mostly of collagen connective tissue....
, and below the sternum it combines with next most superficial muscle (the internal oblique). This insertion runs down by the belly button where it passes over the thick abdomen muscle (the "6/8-pack") and all the ab muscle fibers join together.
Innervation
The transversus abdominis is innervated by the lower intercostal nerves (thoracoabdominal, nerve root T7-T11), as well as the iliohypogastric nerveIliohypogastric nerve
The iliohypogastric nerve is the superior branch of the anterior ramus of spinal nerve L1 after this nerve receives fibers from T12 . The inferior branch is the ilioinguinal nerve....
and the ilioinguinal nerve
Ilioinguinal nerve
The ilioinguinal nerve is a branch of the first lumbar nerve . It separates from the first lumbar nerve along with the larger iliohypogastric nerve....
.
Actions
The transversus abdominis (TVA) helps to compress the ribs and viscera, providing thoracic and pelvic stability. This is explained further here. The transversus abdominis also helps pregnant women deliver their child.Variations
It may be more or less fused with the Obliquus internus or absent. The spermatic cord may pierce its lower border. Slender muscle slips from the ileopectineal line to transversalis fasciaTransversalis fascia
The transversalis fascia is a thin aponeurotic membrane which lies between the inner surface of the Transversus abdominis and the extraperitoneal fascia....
, the aponeurosis of the Transversus abdominis or the outer end of the linea semicircularis and other slender slips are occasionally found. The nerves associated with the transverse abdominus are the intercostal, iliohypogastric, and the ilioinguinal.
Exercise
The most well known method of strengthening the TVA is the vacuum exerciseVacuum exercise
The vacuum exercise is an exercise which involves contracting some internal abdominal muscles, primarily the Transversus abdominis muscle, and not as much the diaphragm, the "six pack" muscles or "abs" which are trained through crunches, leg raises, or other core exercises.Repetitions of the...
. The TVA also (involuntarily) contracts during many lifts; it is the body's natural weight-lifting belt, stabilizing the spine and pelvis during lifting movements. It has been estimated that the contraction of the TVA and other muscles reduces the vertical pressure on the intervertebral discs by as much as 40%. Failure to engage the TVA during higher intensity lifts is dangerous and encourages injury to the spine. The TVA acts as a girdle or corset by creating hoop tension around the midsection.
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.
While it is true that the TVA is vital to back
Back
- People :* Adam Back, British cryptographer* Charles Back, South African winemaker* Chris Back , Australian politician* Ernst Emil Alexander Back , German physicist* Frédéric Back , Canadian animator...
and core
Core (anatomy)
In anatomy, the core refers, in its most general of definitions, to the body minus the legs and arms. Functional movements are highly dependent on the core, and lack of core development can result in a predisposition to injury...
health, the muscle also has the effect of pulling in what would otherwise be a protruding abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
(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 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.