Lecture Note on the Inguinal Canal

INGUINAL REGION

The inguinal region, or groin, extends between the ASIS and pubic tubercle. It is an important

area anatomically and clinically: anatomically because it is a region where structures

exit and enter the abdominal cavity and clinically because the pathways of exit and entrance are

potential sites of herniation.

Although the testis is located in the perineum postnatally, the male gonad originally forms in the

abdomen. Its relocation (migration) out of the abdomen into the perineum through the inguinal

canal accounts for many of the structural features of the region. Traditionally, the testis and

scrotum are dissected and studied in relation to the anterior abdominal wall and the inguinal

region. For this reason, male anatomy receives greater emphasis in this section.

INGUINAL LIGAMENT AND ILIOPUBIC TRACT

Thickened fibrous bands, or retinacula, occur in relationship to many joints that have a wide

range of movement to retain structures against the skeleton during the various positions of the

joint. The inguinal ligament and iliopubic tract, extending from the ASIS to the pubic tubercle,

constitute a bilaminar anterior (flexor) retinaculum of the hip joint. The retinaculum spans the

subinguinal space, through which pass the flexors of the hip and neurovascular structures serving

much of the lower limb. These fibrous bands are the thickened inferolateral-most portions of the

external oblique and aponeurosis and inferior margin of the transversalis fascia. They are major

landmarks of the region.

The inguinal ligament is a dense band constituting the inferiormost part of the external oblique

aponeurosis. Although most fibers of the ligament’s medial end insert into the pubic tubercle,

some follow other courses:

, • Some of the deeper fibers pass posteriorly to attach to the superior pubic ramus lateral to the

tubercle, forming the arching lacunar ligament (of Gimbernat), which forms the medial boundary

of the subinguinal space. The most lateral of these fibers continue to run along the pecten pubis

as the pectineal ligament (of Cooper).

• Some of the more superior fibers fan upward, bypassing the pubic tubercle and crossing the

linea alba to blend with the lower fibers of the contralateral external oblique aponeurosis. These

fibers form the reflected inguinal ligament.

The iliopubic tract is the thickened inferior margin of the transversalis fascia, which appears as a

fibrous band running parallel and posterior (deep) to the inguinal ligament. The iliopubic tract,

seen in the place of the inguinal ligament when the inguinal region is viewed from its internal

(posterior) aspect (e.g., during laparoscopy), reinforces the posterior wall and floor of the

inguinal canal as it bridges the structures traversing the subinguinal space.

The inguinal ligament and iliopubic tract span an area of innate weakness in the body wall in the

inguinal region or groin called the myopectineal orifice. This weak area, occurring in relation to

structures traversing the body wall, is the site of direct and indirect inguinal and femoral hernias.

INGUINAL CANAL

The inguinal canal is formed in relation to the relocation of the testis during fetal development.

The inguinal canal in adults is an oblique passage approximately 4 cm long directed

inferomedially through the inferior part of the anterolateral abdominal wall. It lies parallel and

superior to the medial half of the inguinal ligament. The main occupant of the inguinal canal is

the spermatic cord in males and the round ligament of the uterus in females. These are

functionally and developmentally distinct structures that occur in the same location. The inguinal