An understanding of the anatomy of the female pelvis and lower abdominal wall is essential for obstetrical practice. There may be marked variation in anatomical structures in individual women, and this is especially true for major blood vessels and nerves.
The anterior abdominal wall confines abdominal viscera, stretches to accommodate the expanding uterus, and provides surgical access to the internal reproductive organs. Thus, a comprehensive knowledge of its layered structure is required to surgically enter the peritoneal cavity.
Langer lines describe the orientation of dermal fibers within the skin. In the anterior abdominal wall, they are arranged transversely. As a result, vertical skin incisions sustain increased lateral tension and thus, in general, develop wider scars. In contrast, low transverse incisions, such as the Pfannenstiel, follow Langer lines and lead to superior cosmetic results.
This layer can be separated into a superficial, predominantly fatty layer—Camper fascia, and a deeper, more membranous layer—Scarpa fascia. These are not discrete layers but instead represent a continuum of the subcutaneous tissue layer.
The fibrous aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles join in the midline to create the rectus sheath (Fig. 2-1). The construction of this sheath varies above and below a demarcation line, termed the arcuate line. Cephalad to this line, the aponeuroses invest the rectus abdominis bellies above and below. Caudal to this line, all aponeuroses lie anterior to the rectus abdominis muscle, and only the thin transversalis fascia and peritoneum lie beneath.
Muscles and blood vessels of the anterior abdominal wall.
In the lower abdomen, transition from the muscular to the fibrous aponeurotic component of the external oblique muscles takes place along a vertical line through the anterosuperior iliac spine. Transition from muscle to aponeurosis for the internal oblique and transversus abdominis muscles takes place more medially. For this reason, muscle fibers of the internal oblique are often noted below the aponeurotic layer of the external oblique during creation of low transverse incisions.
The superficial epigastric, superficial circumflex iliac, and external pudendal arteries arise from the femoral artery just below the inguinal ligament in the region of the femoral triangle (see Fig. 2-1). These vessels supply the skin and subcutaneous layers of the anterior abdominal wall and mons pubis. The superficial epigastric vessels course diagonally toward the umbilicus. During low transverse skin incision creation, the superficial epigastric vessels can usually be identified at a depth halfway between the skin and the rectus fascia, several centimeters from the midline.
External Iliac Artery Branches
The inferior “deep” epigastric vessels...