Human Movement Science & Functional Anatomy of the:

Internal Obliques

by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS


Fiber arrangement of external obliques, internal obliques, and transverse abdominis -


Internal Obliques:


  • Origin: Inner surface of ribs 6-12 - interdigitating with the diaphragm, deep layers of the thoracolumbar fascia, anterior 3/4 of the internal lip, 2/3 or the intermediate line, and portion of the iliac crest near the anterior superior spine, and the inguinal ligament.
  • Insertion:  The crest of the pubis, medial part of the pectineal line, linea alba by means of an aponeurosis, medial border of 10 through 12th rib.

    • This internal obliques lay between the external obliques superficially, and the transverse abdominus and peritoneum deep to it.  The fascia of the internal obliques invests with the external oblique to run superficially as the rectus sheath into the linea alba.  It is difficult to differentiate the fibers of the internal obliques, whose fibers run from lateral/inferior to medial/superior, from those of the external obliques and transverse abdominis during palpation.

  • Nerve: segmentally innervated from T7 - T12, L1.
  • Action:

    • Ipsilateral rotator of the spine

    • Posterior pelvic tilt (this may contribute to sacral nutation).
    • Unilaterally the internal oblique may contribute to lateral flexion.
    • By pulling the ribcage inferior and compressing the abdominal contents this muscle aids in forceful respiration.

        Note: some text differentiate fibers of the internal obliques and state the lower