The Round Ligament of the Uterus (Ligamentum Teres Uteri)
The correct answer is e. Lig. teres uteri (round ligament of the uterus), which is the ligament that traverses the inguinal canal and has traditionally been described as terminating in the labium majus, though modern anatomical studies challenge the exact location of its distal insertion.
Anatomical Basis
The female inguinal canal primarily contains the round ligament of the uterus as its main structure, analogous to the spermatic cord in males 1
The round ligament originates from the anterosuperior aspect of the uterus near the tubo-uterine junction and passes under the broad ligament before entering the inguinal canal 2
In female embryological development, the gubernaculum persists as the ovarian round ligament (which becomes the round ligament of the uterus), unlike in males where it guides testicular descent 3, 1
Important Anatomical Controversy
The classical teaching that the round ligament terminates in the labium majus has been challenged by modern anatomical research:
A 2018 cadaveric study of 19 round ligaments found that none terminated in the labia majora 2
Instead, distal attachments were found: after the external inguinal ring (52.6%), before the internal inguinal ring (26.3%), and under the pubic bone (22.1%) 2
A 1991 post-mortem study of 10 females (ages 0-11 years) confirmed the round ligament ended just outside the external ring in all cases, with neither attachment nor extension to the labium 4
A 1997 study of 248 female children with inguinal hernias found the ligament terminated in the hernia sac rather than the labium majus 5
Clinical Significance
The round ligament contains smooth muscle fibers and loose subcutaneous tissue, which can give rise to pathology such as leiomyomas or endometriosis within the canal of Nuck 6, 7
Inguinal hernias are much less common in females than males, with more than 90% of pediatric inguinal hernias occurring in boys 1
Why Other Options Are Incorrect
Lig. suspensorium ovarii (suspensory ligament of ovary): Contains ovarian vessels but does not traverse the inguinal canal 5
Lig. ovarii proprium (ovarian ligament): Connects ovary to uterus, remains intra-abdominal 3
Lig. cardinale (cardinal ligament): Provides lateral support to cervix and upper vagina, does not enter inguinal canal 3
Lig. sacrouterina (uterosacral ligament): Extends from cervix to sacrum posteriorly, remains in pelvis 3, 8