The inguinal canal is a passage in the lower anterior abdominal wall that extends from the deep inguinal ring to the superficial inguinal ring. It is about 4cm long and directed downward and medially. The spermatic cord in males or round ligament in females pass through the canal. The walls of the canal have multiple layers including skin, fascia, and muscles. The canal allows communication between intra-abdominal and scrotal contents while preventing herniation. Mechanisms like the flap valve prevent herniation during increases in intra-abdominal pressure. Direct and indirect inguinal hernias can occur through the canal.

1. Inguinal canal – Anatomy

2. InguinalCanal
• This is an oblique intermuscular passage in the lower part of
the anterior abdominal wall , Situated just above the medial
half of the inguinal ligament

3. Location
Inferior part of the anterolateral
abdominal wall

4. Length &direction
• It is about 4cm(1.5 inches) long, and is
directed downwards, forwards and medially
• The inguinal canal extends from the deep inguinal
ring to the superficial inguinal ring

6. Deep inguinalRing
• An oval opening in the fascia
transversalis situated 1.2 cm above the
midinguinal
point, and immediately lateral to the stem
of the inferior epigastric artery

7. Inguinalcanal

8. Superficial inguinalring
• Is a triangular gap in the external oblique
aponeurosis . It is shaped like an obtuse angled
triangle . The base of the triangle is formed by the
pubic crest, the two sides of the triangle from the
lateral or lower and the medial or upper margins
of the opening. It is 2.5 cm long and 1.2 cm
broad at the base these margins are referred as
crura. At and beyond the apex of the triangle 2
crura are united by intercrural fibers

10. BOUNDARIESOF INGUINAL CANAL

11. THEANTERIORWALL
• .In its whole
extent
• Skin
• Superficial fascia
• External
oblique
aponeurosis
•
• In its lateral one-
third
• The fleshy fibres
of the internal
oblique muscle.

12. Posterior wall of the inguinalcanal
• In ~ 75 % of individuals ,the posterior wall(floor) of the canal is
formed laterally by the aponeurosis of tranversalis abdominal
muscle and the tranversalis fascia
• The remaining , the Posterior wall is tranversalis fascia only
• Medially , the Posterior wall is reinforced by the internal
oblique aponeurosis

13. ROOF
• It is formed by the
arched fibres of the
internal oblique and
transverse
abdominis muscles
and aponeurosis

14. FLOOR
• Is formed by the grooved upper surface of the inguinal ligament;
and at the medial end by the lacunae ligament

15. STRUCTURESPASSING THROUGHTHE CANAL

16. • 1.The spermatic cord in males, or the round ligament of the
uterus in females, enters the inguinal canal through the deep
inguinal ring and passes out through the superficial inguinal
ring.
• 2.The ilioinguinal nerve enters the canal through the
interval between the external and internal oblique muscles
and passes out through the superficial inguinalring.

18. • Allow contents of the scrotum to communicate with intra-
abdominal contents
• Prevent mobile intra-abdominal contents (e.g. Intestine) from
entering the scrotum and possibly becoming damaged, while at
the same time permitting blood vessels, nerves, lymphatics, vas
deferens etc. To supply the scrotal contents

19. MECHANISMOF INGUINAL CANAL
• The presence of the inguinal canal is
the cause of weakness in the lower
part of the anterior abdominal wall.
This weakness is compensated by
the following factors

20. Obliquityof the inguinalcanal
• The two inguinal rings do not lie opposite
to each other.
• Therefore, when the intra- abdominal
pressure rises the anterior and posterior
walls of the canal are approximated, thus
obliterating the passage.
• This is known as the flap valve
mechanism.

21. • The superficial inguinal ring is guarded from behind by the
conjoint tendon and by the reflected part of the inguinal canal.
•
• The deep inguinal ring is guarded from the front by the fleshy
fibres of the internal oblique.

22. Shutter mechanism of the internal oblique
• This muscle has a triple relation to the inguinal
canal. It forms the anterior wall, the roof, and the
posterior wall of the canal. When it contracts the
roof is approximated to the floor, like a shutter.

23. Ball valvemechanism
• Contraction of the cremaster helps the
spermatic cord to plug the superficial
inguinal ring

24. Slit valvemechanism
• Contraction of the external oblique
results in approximation of the two
crura of the superficial inguinal
ring .
• The integrity of the superficial
inguinal ring is greatly increased
by the intercrural fibres.

25. Whenever, there is a rise in intra abdominal
pressure as in coughing , sneezing, lifting heavy
weights all these mechanisms come to play, so
that the inguinal canal is obliterated, its openings
are closed, and herniation of abdominal viscera is
prevented.

28. HESSELBACH’STRIANGLE Triangle is an important
structure as it is the site
for direct hernias. The
triangle has the
following borders:
• 1) Medial border of
rectus
abdominus(medially)
• 2) Inguinal
ligament
(inferiorly)
• 3) Inferior
epigastric
vessels(laterally)

29. Hernias- A briefmention
• Hernias are abnormal outpouchings of the
abdominal contents (such as the small intestine)
from the cavity in which they belong.
• There are two main types of hernias that occur at
the inguinal region. Direct hernia and indirect
hernia.

30. Indirect or obliquehernia
• These are the most common inguinal hernias, in this the
contents of the abdomen enter the deep inguinal ring and
traverse the whole length of the inguinal canal to come out
through the superficial inguinal ring

31. Coverings of indirecthernias
• Peritoneum
• Internal spermatic fascia
(from transversalis fascia)
• Cremaster muscle & fascia
(from transversus abdominis
and internal oblique mm.)
• External spermatic fascia
(from external oblique m.)
• Superficial fascia
• Skin

32. Direct Hernias
• Direct hernias occurs lateral to the epigastric vessels. They do
not protrude through any ring, but through an area of
weakness in the posterior wall of the inguinal canal; this area
is likely to be Hesselbach’s Triangle.

33. Coverings of directhernias
• Peritoneum
• Transversalis fascia
• Conjoint tendon
• External oblique
aponeurosis
• Superficial fascia
• Skin