Human Movement Science & Functional Anatomy of the:
by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS
Transverse Abdominis via Grey's Anatomy: 20th Edition - http://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Transversus_abdominis.png/396px-Transversus_abdominis.png
Transverse Abdominis (TVA):
- Lateral Attachment: The lateral raphe of the thoracolumbar fascia between the iliac crest and 12th rib, extending superiorly to the internal aspects of the lower six costal cartilages (interdigitating with the diaphragm),and inferiorly along the anterior two-thirds of the inner lip to the lateral third of the inguinal ligament (13).
- Medial Attachment: "...is a complex and variable bilaminar aponeurosis (13)." The lower fibers extend inferiorly blending with the internal obliques to form the conjoint tendon which attaches to the pubic crest behind the superficial inguinal ring, the remaining fibers below the umbilicus blend with the abdominal fascia, passing in front of the the rectus abdominis to invest in the linea alba. Above the level of the umbilicus the abdominal fascia is bilaminar passing both anterior and posterior to the rectus abdominis (enveloping the rectus abdominis) - the fibers of the TVA invest in the posterior fascia and linea alba via two separate layers of muscle with distinct fiber directions running oblique inferior and oblique superior. The inferiorly turned fibers run continuous with the superiorly turned fibers on the contralateral side and visa-versa (13).
- The transverse abdominis lays between the internal obliques superficially and the parietal peritoneum inferiorly (abutting the visceral peritoneum and internal organs) (15). It is not likely possible to differentiate the fibers of the internal obliques and transverse abdominis during palpation - adding to the difficulty of this palpation is the thicker, striated fibers of the external obliques lying superficially.
- Nerve: Intercostal nerves via nerve roots T7 through T12, iliohypogastric and ilioinguinal nerves via nerve root L1.
- .Stabilization of lumbar spine, sacroiliac joint