Clinical Anatomy 22:639 (2009)
Letters to the Editor
What Are the Actual Boundaries of
Inguinal Canal?
To the Editor, Clinical Anatomy:
Many textbooks of anatomy define the inguinal
canal as an oblique intermuscular passage situated
in the lower part of the anterior abdominal wall. Precisely, it is situated above the medial third of the inguinal ligament. It extends from the deep inguinal
ring to the superficial inguinal ring. The anterior
boundary of the inguinal canal is formed by the aponeurosis of the external oblique muscle throughout
its length and by the fleshy part of the internal
oblique in the lateral third. The posterior boundary is
formed by the transversalis fascia throughout and
the conjoint tendon in the medial part. The roof is
formed by the arching fibers of the internal oblique,
and the floor is formed by the inguinal ligament.
According to the widely used textbooks of anatomy
(Snell, 2000; Drake et al., 2005; Moore and Dalley,
2006), the inguinal canal contains the ilioinguinal
nerve and the spermatic cord in males and the round
ligament of the uterus in females. According to the
textbook explanations, the inguinal canal is the path
occupied by the gubernaculum during the descent of
the gonad, importantly the testis in males. The gubernaculum is a mesenchymal band that extends from
the lower pole of the developing gonad to the genital
swellings. In the developing male, it will carry with it
the layers of anterior abdominal wall, namely the
transversalis fascia (which forms the internal spermatic fascia), the internal oblique (as the cremasteric
fascia and muscle), and the external oblique aponeurosis (as the external spermatic fascia). When the testis passes through the inguinal canal, it ‘‘drags’’ the
ductus deferens, testicular artery, pampiniform
plexus of veins, lymphatics, and nerve plexuses of the
testis through the inguinal canal. These structures will
form the spermatic cord.
It can be argued that the inguinal canal is the tubular canal present in the internal spermatic fascia
because internal spermatic fascia is the innermost
tube that contains the contents of the spermatic
cord. In fact, the internal spermatic fascia and the
cremaster muscle should be included in the boundaries of inguinal canal. When the contents of an indirect hernia push into the inguinal canal, they get into
the canal formed by the fascia transversalis (internal
spermatic fascia) at the deep inguinal ring. This
canal continues into the scrotum. Textbooks of anatomy do not mention the internal spermatic fascia
and cremaster muscle as the contents of spermatic
cord. They are the coverings of the spermatic cord.
It is my strong opinion that the definition of the inguinal canal as an oblique intermuscular passage
that extends from deep inguinal ring to superficial inguinal ring is misleading. It would be better to define
inguinal canal as a ‘‘canal formed by the fascia transversalis’’ in the lower part of the anterior abdominal
wall. If we must retain the existing explanation of the
inguinal canal, we must add the internal spermatic
fascia and cremaster muscle in all the boundaries
(roof, floor, anterior, and posterior) of inguinal canal
because they surround the spermatic cord as a tube.
Satheesha Nayak B*
Department of Anatomy
Melaka Manipal Medical College
International Centre for Health Sciences, Manipal
Karnataka, India
REFERENCES
Drake RL, Vogl W, Mitchell AW. 2005. Gray’s Anatomy for Students.
1st Ed. Philadelphia: Elsevier Churchill Livingstone. p 258–262.
Moore KL, Dalley AF. 2006. Clinically Oriented Anatomy. 5th Ed.
Baltimore: Lippincott Williams & Wilkins. p 215–222.
Snell RS. 2000. Clinical Anatomy for Medical Students. 6th Ed.
Baltimore: Lippincott Williams & Wilkins. p 149–153.
*Correspondence to: Satheesha Nayak B, Associate Professor of
Anatomy, Melaka Manipal Medical College, Manipal Campus,
International Centre for Health Sciences, Madhav Nagar, Manipal,
Udupi 576 104, Karnataka, India.
E-mail: nayaksathish@yahoo.com
Received 18 March 2009; Accepted 22 March 2009
Published online 6 May 2009 in Wiley InterScience (www.
interscience.wiley.com). DOI 10.1002/ca.20806
C 2009
V
Wiley-Liss, Inc.