Rectus Abdominis and Pyramidalis

This course describes the anatomy and integrated function of the rectus abdominis and pyramidalis muscle (a.k.a. the abdominal muscle, abdominis muscle, abs, rectus muscle, 6-pack muscles, or six-pack muscle). The rectus abdominis originates on the pubic symphysis and inserts on the costal cartilages of the fifth through seventh ribs and the xiphoid process of the sternum. The pyramidalis originates on the ramus of the pubis and inserts into the linea alba, but the pyramidalis is absent in about 20% of the population. The rectus abdominis is composed of a fairly even distribution of type I muscle fibers and type II muscle fibers; however, a larger proportion of type II fibers is more common. The rectus abdominis and pyramidalis cross the torso and pelvis, influencing motion of the pelvis, thoracic spine, lumbar spine, and ribs. The rectus abdominis is the primary lumbar flexor, will contribute to a posterior pelvic tilt, and potentially lateral flexion of the spine. This course also describes the role of the rectus abdominis muscle in facet joint arthrokinematics, fascial integration (integration of abdominal wall muscles), postural dysfunction, and subsystem integration. Sports medicine professionals (personal trainers, fitness instructors, physical therapists, massage therapists, chiropractors, occupational therapists, athletic trainers, etc.) must be aware of the integrated function of the rectus abdominis for the detailed analysis of human movement, and the development of sophisticated exercise programs and therapeutic (rehabilitation) interventions. Further, this course is essential knowledge for future courses discussing injury prevention and physical rehabilitation (e.g. “weak core,” abdominal wall pain, diastasis recti, hip flexor strain, sports hernias, groin injury, anterior pubic ligament injury, low back pain), the synergistic function of the rectus abdominis and pyramidalis (e.g. lumbar flexion with the external obliques, internal obliques, and psoas), and rectus abdominis muscle specific exercises and techniques for enhancing sports performance (e.g. ensuring ideal rectus abdominis length for optimal core stability, strength, power, hypertrophy, etc.).

Brookbush Institute’s most recommended techniques for the Rectus Abdominis (see videos below):

• Activation: Ball Crunch
• Activation: Kneeling Static Chop
• Reactive Activation: Crunch and Catch
• Integration: Anterior Oblique Subsystem Integration Step-Up to Chest Press

Caption: Cadaver dissection of the rectus abdominis