Inferior Epigastric Artery Case File

Inferior Epigastric Artery Case File

Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 17

A 31-year-old woman with one healthy child presents with a 2-year history of an inability to conceive. She states that her menstrual periods began at age 12 and occur at regular 28-day intervals. A biphasic basal body temperature chart is recorded. She denies having any sexually transmitted disease, and a hysterosalpingogram shows patent uterine tubes and a normal uterine cavity. Her husband is 34 years old, and his semen analysis is normal. In the presence of several normal test results for infertility, a laparoscopic examination of the pelvic cavity is scheduled. The physician performing the procedure carefully places the trocar lateral to the rectus abdominis muscle and its sheath to avoid injury to a major artery.

⯈ What artery is being avoided?

⯈ What is the anatomical location of this structure?

ANSWER TO CASE 17:

Inferior Epigastric Artery

Summary: An infertile couple is being evaluated, and several tests for infertility have shown normal results. A laparoscopic examination of the pelvic cavity is performed to rule out the presence of endometriosis. The trocar is specifically placed lateral to the rectus abdominis muscle and its sheath to avoid a major artery.

• Artery that is avoided: Inferior epigastric artery

• Anatomical location of this artery: Posterior to the rectus abdominis within the rectus sheath

CLINICAL CORRELATION

The presence of several normal test results indicates a need to rule out endometriosis in this infertile couple. Endometriosis is defined as ectopic endometrial tissue outside the uterus, typically adherent to the pelvic peritoneum. This tissue responds to a woman’s hormonal cycles in the same way that the lining of the uterus responds. Although the mechanism is not fully understood, endometriosis may cause infertility by inhibiting ovulation, producing adhesions, or interfering with fertilization. Laparoscopic examination of the pelvic cavity is indicated and, if possible at this time, ablation of the endometrial tissue.

APPROACH TO:

Anterior Abdominal Wall

OBJECTIVES

1. Be able to describe the arterial blood supply of the anterior abdominal wall

2. Be able to describe the relation of these vessels to the musculature of the anterior abdominal wall, including the rectus sheath

DEFINITIONS

BIPHASIC BASAL BODY TEMPERATURE CHART: Elevation of the oral temperature during the second half of the menstrual cycle, indicating that the patient has ovulated

HYSTEROSALPINGOGRAM: Radiologic study in which radiopaque dye is injected into the uterine lumen through a transcervical catheter to evaluate the uterine cavity or the patency of the uterine tubes

LAPAROSCOPY: Surgical technique to visualize the peritoneal cavity through a rigid telescopic instrument called a laparoscope

ENDOMETRIOSIS: Condition in which the lining tissue of the uterus, the endometrium, is far outside the uterus, typically in the pelvic cavity or on the abdominal wall

DISCUSSION

The anterior abdominal wall is composed of three paired flat muscles that, in general, arise from bony structures posteriorly and whose fibrous aponeuroses form the rectus sheath and meet to form the linea alba. These muscles are, from superficial to deep: the external abdominal oblique, internal abdominal oblique, and transversus abdominis (Figure 17-1). These muscles are supplied by segmental branches of the thoracic and abdominal aorta: the 10th, 11th, and 12th (subcostal) intercostal

arteries and the 1st or 2nd lumbar arteries. These arteries, their companion veins, and the nerves supplying the muscles are all found in the interval between the internal abdominal oblique and the transversus abdominis muscles, known as the neurovascular plane. Superficial and deep circumflex iliac arteries arise from the femoral and external iliac arteries, respectively; course parallel to the inguinal ligament; and supply the inferior abdominal wall in the inguinal region. The superficial epigastric arteries lie in the superficial fascia between the umbilicus and the pubic bone. The internal thoracic arteries divide into two terminal branches: the superior epigastric and musculophrenic arteries (Figure 17-2).

Figure 17-1. Muscles of the anterior abdominal wall. (Reproduced, with permission, from Lindner HH. Clinical Anatomy. East Norwalk, CT: Appleton & Lange, 1989:291.)

Figure 17-2. Arteries of the anterior abdominal wall. (Reproduced, with permission, from Lindner HH. Clinical Anatomy. East Norwalk, CT: Appleton & Lange, 1989:299.)

The anterior central region of the abdominal wall is formed by the paired rectus abdominis muscles, which attach to the pubic bone inferiorly and the rib cartilages superiorly, and lie just lateral to the linea alba. Each muscle is subdivided into short belly segments by typically three or more tendinous inscriptions. Each muscle is contained in a fibrous compartment, the rectus sheath, which is formed by the aponeuroses of the three flat abdominal muscles. Enclosing the superior three-fourths of each rectus muscle are anterior and posterior layers to the sheath. In this region, the aponeurosis of the internal abdominal muscle divides, and portions will pass anteriorly and posteriorly to the rectus muscle. It follows that the aponeuroses of the external oblique muscle and the transversus abdominis muscles must pass anteriorly and posteriorly to the rectus, respectively. At about the midpoint between the umbilicus and the pubic bone, the aponeuroses of all three flat abdominal muscles pass anterior to the rectus sheath; therefore, the inferior one-fourth of the rectus muscle has only an anterior rectus sheath. The inferior margin of the posterior rectus sheath can be identified in this region of transition as the arcuate line. The rectus sheath also contains the pyramidalis muscles, superior and inferior epigastric vessels, and terminations of the intercostal nerves that innervate the abdominal muscles. The superior one-fourth of the rectus muscle is supplied by the medial terminal branch of the internal thoracic artery, the superior epigastric artery. The inferior epigastric artery arises from the external iliac artery just before its exit from the abdomen to become the femoral artery. Each artery courses medially, external to the peritoneum, along the posterior surface of the rectus muscles. The superior and inferior epigastric arteries anastomose about halfway between the umbilicus and the xiphoid process.

COMPREHENSION QUESTIONS

17.1 A surgeon entering the abdominal cavity through the abdominal wall will take care to avoid injury to the vessels and nerves within the wall. The main portion of these vessels and nerves will be found immediately deep to which of the following?

A. Skin

B. Superficial fascia

C. External abdominal oblique muscle

D. Internal abdominal oblique muscle

E. Transversus abdominis muscle

17.2 As a surgeon performing an appendectomy, you encounter an artery and vein in the superficial fascia of the lower abdominal wall. These vessels are most likely which of the following?

A. Superficial epigastric artery and vein

B. Superficial circumflex iliac artery and vein

C. Intercostal artery and vein

D. Inferior epigastric artery and vein

E. Superior epigastric artery and vein

17.3 During surgery, you must incise the anterior rectus sheath between the xiphoid process and the umbilicus. In this region, the sheath is derived from the aponeurosis of which of the following?

A. External abdominal oblique only

B. Internal abdominal oblique only

C. External and internal abdominal oblique

D. Internal oblique and transversus abdominis

E. Transversus abdominis only

17.4 During a laparoscopic procedure, you observe the inferior epigastric vessels ascending on the posterior surface of the rectus abdominis muscle. They suddenly disappear from view by passing superior to which of the following?

A. Falx inguinalis

B. Linea semilunaris

C. Falciform ligament

D. Arcuate line

E. Transversalis fascia

ANSWERS

17.1 D. The main course of the intercostal vessels and nerves is deep to the internal abdominal oblique muscle in the neurovascular plane.

17.2 A. The superficial epigastric vessels lie within the superficial fascia.

17.3 C. The superior three-fourths of the anterior rectus sheath is derived from the aponeuroses of the external and internal abdominal oblique muscles.

17.4 D. As the inferior epigastric vessels ascend on the posterior surface of the rectus abdominis muscle, they will pass superiorly to the arcuate line, anteriorly to the posterior rectus sheath.

ANATOMY PEARLS

⯈ The neurovascular plane of the anterolateral abdominal wall lies deep to the internal abdominal oblique muscle.

⯈ Along the superior three-fourths of the rectus muscles, the internal oblique aponeurosis splits to contribute to the anterior and posterior rectus sheath layers.

⯈ The inferior epigastric artery arises from the external iliac artery, lies on the posterior surface of the rectus muscle, and serves as its main blood supply.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:136−137, 146−147. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:186−196, 198−199. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 247, 249, 251.

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