Illustraion from Gray's Anatomy of the Abdominal Fascia, External Obliques, Iliac Crest, and Latissimus Dorsi (Lateral View)

External Obliques - By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (Image: Gray's Anatomy, Plate 392, Public Domain,


What’s in a name?

  • External (adj.) - early 15c., from Middle French externe or directly from Latin externus "outside, outward" (Etymology Online)
  • Oblique (adj.) - early 15c., from Middle French oblique (14c.) and directly from Latin obliquus "slanting, sidelong, indirect," from ob "against" (see ob-) + root of licinus "bent upward" (see limb (n.1)). As a type of muscles, in reference to the axis of the body, 1610s (adj.), 1800 (n.). (Etymology Online)
    • "the most external muscle that runs slanting"

Attachments and Innervation

  • Origin: The external surfaces of ribs 5 - 9, interdigitating with the serratus anterior, and the external surfaces of ribs 10 - 12 interdigitating with the latissimus dorsi (1-3).
  • Insertion: The medial fibers invest in the abdominal fascia (running superficial to the rectus abdominis) terminating at the linea alba (a tendinous raphe that extends from the xyphoid process to pubis) (1-5). The more lateral fibers invest in the inguinal ligament from pubic tubercle to the anterior superior iliac spine (ASIS), and external lip of the anterior half of the iliac crest (1-5). The insertion of the external obliques is primarily tendinous and is known as the aponeurosis of the external obliques (4).
  • Nerve: Segmentally innervated by branches of