Rectus Abdominis (REK-tus ab-DOM-i-nus)
Internal Oblique (o-BLEEK)
External Oblique (o-BLEEK)
Transversus Abdominis
This is a long flat muscle that is divided into four bellies by horizontal fibrous bands, giving it a “washboard” appearance. It originates bilaterally from the pubic symphysis and pubic crest, inserting on the xyphoid process (at the bottom of the sternum) and, more laterally, the cartilage of the fifth, sixth, and seventh ribs.
Contracting the rectus abdominis flexes the trunk forward, or, if the insertion is fixed, lifts the pelvis. This is demonstrated in Uttanasana and Tolasana, respectively. Tightness in this muscle limits the depth of back bends such as Urdhva Danurasana and Purvottanasana.
Contracting the rectus abdominis also compresses the abdominal contents, producing an “air bag” effect, which is thought to prevent hyperextension of the lumbar spine, protecting it when extended (as in back bends).
This is a sheet-like muscle with fibers running opposite to the internal oblique. It is the larger of the two obliques and lies superficial. Its anterior fibers are more superior, originating from the front of the ribs, crossing diagonally forward and downward, and inserting on the linea alba. Its lateral fibers are more posterior, originating from the back of the ribs, crossing downward and forward, and inserting on the structures at the front of the pelvis.
Contraction of the external oblique draws the shoulder forward. This action combines with contraction of the contralateral (other side) internal oblique, accentuating twisting poses. Tightness in this muscle limits these postures. Contraction assists in compressing the abdominal contents and contributes to the “air bag” effect, protecting the lumbar spine.
This is a thin sheet-like muscle located on the side of the trunk. Its fibers cross diagonally upward and forward from the iliac crest, inserting on the lower ribs and the linea alba (a band of fibrous tissue running down the front of the abdomen).
Contraction of the internal oblique draws the opposite shoulder forward and bends the trunk laterally. This action accentuates twisting postures such as Parivrtta Trikonasana. Contracting the internal oblique also contributes to the “air bag” effect described for the rectus abdominis.
The transversus abdominis is the deepest of the abdominal muscles. Its fibers run horizontally, originating on the iliac crest, the inguinal ligament, and the thoracolumbar fascia and inserting on the lower costal cartilages. Contracting the transversus abdominis compresses the abdomen and tones the abdominal organs. This muscle is important for Udyana Bandha and Nali. Awaken and strengthen it in Navasana.
Symphysis pubis and pubic crest.
Lower borders of the lateral third of the inguinal ligament, iliac crest, thoracolumbar fascia, and linea alba.
Ribs 5 through 12 and lower section of the latissimus dorsi.
Zyphoid process, costal cartilages 5, 6, and 7.
Linea alba and ribs 9 through 12.
Linea alba, inguinal ligament, and anterior half of the iliac crest.
Origin: Iliac crest, inguinal ligament, and thoracolumbar fascia.
Insertion: Lower costal cartilages.
Intercostal nerves (thoracic nerves 7 through 12), iliohypogastric and ilioinguinal nerves (thoracic nerve 12 and lumbar nerve 1).
Chakra illuminated: Third.
Erector spinae and quadratus lumborum.
Same-side muscles are rotational antagonists.
Each other (for abdominal compression).
Opposite-side muscles are rotational synergists. They can assist each other, turning the body.
Flexes the trunk and compresses the abdomen.
Contracting the rectus abdominis draws the trunk forward and deepens Prasarita Padottanasana. Contracting the iliopsoas and quadriceps accentuates this action.
The rectus abdominis awakens in Navasana.
1) External Oblique: Unilateral (one-sided) contraction rotates the same-side shoulder forward and laterally flexes the trunk.
Bilateral contraction flexes the trunk and compresses the abdomen.
2) Internal Oblique: Unilateral contraction rotates the contralateral (opposite side) shoulder forward and laterally flexes the trunk.
Bilateral contraction flexes the trunk and compresses the abdomen.
The upper-side internal oblique and the lower-side external oblique contract in Utthita Trikonasana, turning the trunk. Their opposites are lengthened by this action.
Contracting the abdominal muscles compresses the abdominal organs and provides additional support to the muscles surrounding the lumbar spine. This mechanism comes into play when we lift a heavy object and in “valsalva.” This concept can be applied during Yoga postures. Only light contraction is necessary to benefit from this action.
Light contraction of the abdominals in back bends also opposes hyperextension of the lumbar spine and tones the abdominals (through eccentric contraction). Contracting the abdominals in this way activates Udyana Bandha (in the region of the solar plexus), illuminating the third Chakra.
Twisting postures create a “wringing” effect on the abdominal organs. This helps to flush the liver and other organs, directing blood and lymphatic fluid into the larger vessels of the cardiovascular system, eliminating toxins.
The abdominal muscles are the core prime movers in the twisting postures. Combine them with other muscular synergists of the twist. For example, in twisting Siddhasana, the sternocleidomastoid, latissimus dorsi, and triceps of one side assist the biceps and hamstrings of the other side to accentuate the twist.
Combine the actions of various muscles to create synergy in your posture. Contract the posture’s synergists to lengthen the antagonists.
These illustrations demonstrate that contracting the rectus abdominis, iliopsoas, quadriceps, deltoids, and biceps in Prasarita Padottanasana stretch the erector spinae, hamstring, and gastrocnemius muscles.
Prasarita Padotanasana–synergists
Prasarita Padotanasana–antagonists