fetal life and is merely in contact with the posterior aspect of the tunica. An indirect congenital hernia

enters the patent tunica vaginalis.

Figure 72-13. The inguinal (Hesselbach) triangle.

Figure 72-14. The component layers covering the contents of the spermatic cord.

The cord structures enclosed by the coverings described earlier are the ductus (vas) deferens, the

pampiniform venous plexus, the testicular artery, and the genital branch of the genitofemoral nerve, a

branch of the lumbar plexus (Figs. 72-9, 72-11, and 72-15).

Branches of the Lumbar Plexus

The nerves crossing the iliac fossa are some of the most variable in the body. This variability may be

the cause of frequent intraoperative injury to the fragile nerves. The lumbar plexus is formed by roots

from the 12th thoracic nerve and the first through fourth lumbar nerves. Cutaneous territories

innervated by branches of the lumbar plexus are seen in Figure 72-15A. The five terminal branches

commonly encountered in laparoscopic herniorrhaphy can be discerned in many people as they course

across the iliacus muscle covered by peritoneum and the iliac fascia (a portion of the transversalis–

endopelvic fascia). The nerves form within or deep to the psoas major muscle (Fig. 72-15B), often

ramifying with other nerves within or close to the muscle. The nerve branches initially lie within the socalled triangle of pain,13 bordered medially by the psoas muscle, anteriorly and inferiorly by the

iliopubic tract, and laterally by the iliac crest. With the exception of the genital branch of the

genitofemoral nerve, the branches of the lumbar plexus destined for the thigh run beneath the iliopubic

tract.

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Figure 72-15. A: The cutaneous territories innervated by several branches of the lumbar plexus. B: Some of the branches of the

lumbar plexus seen from within the abdomen.

The most anterior of the nerves encountered, the genitofemoral nerve, is also the most variable. This

nerve may occur as a single trunk lying deep to the peritoneum and fascia on the anterior surface of the

psoas muscle. The nerve may also divide into its component genital and femoral branches within the

muscle. The genital branch travels with the spermatic cord, entering at the deep inguinal ring; it

ultimately innervates the cremaster muscle and the lateral scrotum. The femoral branch of the nerve

innervates the skin of the proximal mid-thigh.

The lumbar plexus branch encountered immediately deep to the lateral aspect of the psoas muscle is

the large femoral nerve. Although not routinely encountered during laparoscopy, the femoral nerve has

been injured in some cases.14 The lateral femoral cutaneous nerve crosses the iliac fossa under the iliac

fascia to run deep to the iliopubic tract and the inguinal ligament, which it pierces to enter the thigh.

The iliohypogastric nerve typically arises with the ilioinguinal by a common trunk from the first

lumbar nerve. They may exchange fibers within the muscle, but they usually diverge immediately to

form individual nerves. The iliohypogastric nerve crosses the iliac fossa just inferior to the kidney and

pierces the transversus abdominis. The subsequent course of the nerve carries it between the transversus

and the internal abdominal oblique until it pierces the aponeuroses of both obliques just above the

external inguinal ring.

The ilioinguinal nerve normally crosses the iliac fossa just inferior to the iliohypogastric nerve. In its

typical further course, the nerve pierces the transversus abdominis and internal abdominal oblique

above the iliac crest and eventually enters the inguinal canal. The nerve may run more diagonally

through the iliac fossa and then pierce the iliopubic tract to reach the inguinal canal.15 This path “can

obviously render the nerve more vulnerable to iatrogenic injury.”

Vasculature of the Abdominal Wall and Deep Inguinal Region

The vasculature of the deep inguinal region and anterior abdominal wall has been analyzed by surgeons

for well over 100 years. The importance and variability of these vessels have been underscored by the

ominous mnemonics used to refer to them – “crown of death” (corona mortis) and “triangle of doom.”

The primary blood supply to the deep anterior wall is from the inferior epigastric artery. This artery is a

branch of the external iliac artery. In many cases, an artery called the “aberrant” obturator artery arises

from the inferior epigastric, which joins the “normal” obturator artery and thereby forms a circle – the

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corona mortis – before entering the obturator foramen. Injury to the circle, usually sustained while the

surgeon is working in the area of the Cooper ligament, causes copious bleeding. Recent studies have

indicated that aberrant obturator vessels are present in between 60% and 90% of the whole pelves

studied.16,17

The veins in this area are also prone to injury because many, especially the iliopubic veins and

obturator veins and their tributaries, may be much larger than their accompanying arteries. One

network of veins in the area is situated on the inferior deep surface of the rectus muscles. The veins of

this network, which anastomose with the pubic branches discussed earlier, have been called the rectusial

veins.18

The vessels in the vascular compartment of the deep inguinal region are the external iliac artery and

vein. They arise within a triangular area bordered laterally by the gonadal vessels and medially by the

ductus deferens. The primary continuations of the external iliac vessels are the femoral artery and vein.

The inferior epigastric artery is a branch of the external iliac. The obturator artery may arise from

either of these arteries as a replacement or accessory to the obturator branch of the internal iliac artery.

A final vessel to consider in this review is the deep circumflex iliac artery (Fig. 72-10). The origin of

this artery is extremely variable, but its course is predictable along the iliopubic tract. It pierces the

transversalis fascia and runs along the iliac fossa to anastomose eventually with a deep lumbar artery.

Because the deep circumflex artery runs along the iliopubic tract, it can inadvertently be stapled or

otherwise injured during laparoscopic herniorrhaphy.

Pelvic Floor and Obturator Muscles

The pelvic musculature normally affords remarkable support to the structures within the true pelvis.

Although a myoaponeurotic hammock-like sheet forms the pelvic diaphragm, obturator muscles and

membrane, and urogenital diaphragm, herniation of fat or viscera through or around any of these layers

occurs. The potential for hernia formation is increased because of the openings through which many

structures exit or enter the pelvis.

The Latin term obturator is translated as “stopper for a bottle.” The aptly named obturator internus,

along with its membrane and the obturator externus, closes off nearly all the large obturator foramen.

The small superolateral aperture through which the obturator vessels and nerve pass is the site where

obturator hernias form. The obturator internus arises from the deep surface of parts of all three pelvic

bones. The muscle fibers converge on a tendon, which leaves the pelvis through the lesser sciatic

foramen to insert on the greater trochanter. The dense internal obturator fascia covers the muscle and is

thickened to form the arcuate ligament, from which the levator ani muscles (the pelvic diaphragm) are

in part suspended. The obturator internus fascia splits to enclose the pudendal vessels in the pudendal

canal. The external obturator muscle arises from the pelvic bones surrounding the obturator foramen

and from the anterior portion of the obturator membrane. The external obturator muscle is supplied by

the obturator nerve and vessels.

The component muscles of the bowl-shaped pelvic diaphragm, the pubococcygeus, iliococcygeus, and

puborectalis, along with the coccygeus form the floor of the pelvis. The pubococcygeus arises from the

posterior aspect of the pubis and the thickened portion of the internal obturator fascia, called the

tendinous arch (Fig. 72-16), that spans the distance between the pubis and ischial spine. The

puborectalis, the midportion of the diaphragm, arises from the pubis and loops around the rectum as the

puborectal sling. The iliococcygeus is suspended at its origin from the tendinous arch and inserts on the

coccyx. The coccygeus muscle completes the diaphragm posteriorly, arising from the ischial spine and

inserting on the sides of the coccyx.

The area remaining between the sacrum and the greater sciatic foramen is filled for the most part by

the piriformis muscle. The piriformis arises from the anterior surface of the second through fourth sacral

vertebrae and the sacrotuberous ligament. This muscle exits the pelvis through the greater sciatic

foramen, which is thereby divided into suprapiriform and infrapiriform portions (Figs. 72-16 and 72-

17). The superior gluteal nerves and vessels pass through the suprapiriform foramen, whereas the

inferior gluteal nerves and vessels in company with the sciatic nerve pass through the infrapiriform

foramen.

The most pronounced deficit in the pelvic diaphragm is situated anteriorly, where an aperture must

allow the urogenital structures to pass out of the pelvis. This area is reinforced by the urogenital

diaphragm, a structure primarily consisting of the superficial and deep transverse perineal muscles. The

deep transverse perineal muscle is enclosed by a weak superior fascia and a sturdier inferior perineal

fascia. The urogenital diaphragm recently has been shown to be more funnel shaped than sandwichlike,

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