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CHAPTER 1  Surgical Anatomy of the Female Pelvis

or inscriptions. These are fibrous interruptions within the muscle that firmly attach it to the rectus abdomi- nis sheath. In general, they are confined to the region above the umbilicus, but they can be found below it. At these fibrous interruptions, the rectus sheath is attached to the rectus muscle and thus the two structures are dif- ficult to separate (e.g., during a Pfannenstiel incision). The pyramidalis muscles arise from the pubic bones anterior to the rectus abdominis and insert into the mid- line linea alba several centimeters above the symphysis. Their development varies considerably among individu- als. Their strong attachment to the midline makes separa- tion here difficult by blunt dissection. Flank Muscles Lateral to the rectus abdominis muscles lie the broad, flat muscles of the flank. Their aponeurotic insertions join to form the rectus sheath, which covers the rectus abdominis muscles. Because of its importance, the rec- tus sheath is further discussed below. The most superficial of these muscles is the external oblique. Its fibers run obliquely anteriorly and inferi- orly from their proximal origin on the lower eight (5 through 12) ribs to the broad distal insertions of their aponeuroses on the iliac crest, pubic tubercle, and linea alba. The inferior margin of the external oblique apo- neurosis is thickened, and its free posterior edge forms the inguinal ligament. The fibers of the internal oblique muscle fan out superiorly and medially from their origin in the anterior two thirds of the iliac crest, the lateral part of the inguinal ligament, and the thoracolumbar fascia to their distal attachments on the inferior borders

TABLE 1.1 Abdominal Wall Layers Skin Subcutaneous tissue Fatty layer (Camper fascia) Membranous layer (Scarpa fascia) Musculoaponeurotic layer

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Rectus Abdominis and Pyramidalis Muscles Each paired rectus abdominis muscle originates from the sternum and cartilages of ribs 5 through 7 and inserts into the anterior surface of the pubic bone. Each muscle has three to four tendinous intersections Arcuate line—lower limit of the posterior layer, approximately one third of the distance from the umbilicus to the pubic crest. Below this line, posterior surface of rectus abdominis muscles in contact with transversalis fascia Transversalis fascia Preperitoneal fat Peritoneum Rectus sheath—formed by aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles (flank muscles). Invests rectus abdominis and pyramidalis muscles (ver- tical muscles). Fuse in the midline at the linea alba and laterally at the linea semilunaris. Anterior layer—formed by external oblique and internal oblique (split) aponeuroses Posterior layer—formed by internal oblique (split) and transver- sus abdominis aponeuroses

External oblique

External oblique

Internal oblique

Anterior sup. iliac spine

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Inguinal ligament Superficial inguinal ring

Pyramidalis

FIGURE 1.1  External oblique, internal oblique, and pyramidalis muscles. (The original illustration is in the Max Brödel Archives in the Department of Art as Applied to Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. Used with permission.)

Round lig.

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