Regional morphology of the transversus abdominis and obliquus internus and externus abdominis muscles

Variations in the Pattern of Formation of the Abdominis Rectus Muscle Sheath among Kenyans

“…Their location deep to the rectus abdominis coupled by the fact that the PWRS is not firmly attached to the RA may be a biomechanical adaptation. As evidenced by physiological studies, these fascicles of TA are recruited before other muscles of anterior abdominal wall during truncal flexion and respiration (Hodges et al, 1997;Urquart et al, 2005b). Contraction of TA therefore increases the separation between the PWRS and the RA.…”

Role of intra-abdominal pressure in the unloading and stabilization of the human spine during static lifting tasks

“…For the reference cases in which no coactivity was assumed in concurrence with IAP, the IAP was assumed to be generated solely by TA coactivity. In this case, fascicles of TA were considered to be oriented in the transverse plane without having any axial compressive force penalty despite the fact that some of its fascicles especially in the middle and lower regions are somewhat oblique [72]. Other abdominal muscles (RA, EO, and IO) were all modeled by a single fascicle.…”

“…Fascicles of IO are suggested to be primarily oriented transversely in which case, similar to TA, they would not cause appreciable flexor moment and axial compression penalties on the spine [20,22]. Although this might be true for IO fascicles at lower regions [56,72] the remaining fascicles attaching iliac crest and rib cage are oriented obliquely at $50-75°to the horizontal plane [69,72] which can generate considerable flexor moment and axial compression on the spine. Those fascicles of IO which are oriented more transversely may redirect their force to the RA sheath via linea semilunaris to enhance their effective moment arm [47].…”

Ultrasound assessment of transversus abdominis muscle contraction ratio during abdominal hollowing: a useful tool to distinguish between patients with chronic low back pain and healthy controls?

“…The rationale behind the treatment concept is that the segmental stability of the lumbar spine is controlled by deep-lying muscles, such as multifidi and transversus abdominis (TrA) that have an anatomical connection to the lumbar spine [43]. The relationship between anatomical structure and function has been described by Panjabi [32]: stability in a lumbar segment requires a coordinated interaction between the passive subsystem (osteoligamentous structures), the active subsystem (muscles) and the neural subsystem (central and peripheral nervous systems controlling the muscles).…”