1. INGUINAL CANAL
Dr.LUBNA NAZLI
ASST. PROF. ANATOMY
RAK MHSU
Dt. 12/11/2007
Mon 8.30 a.m-9.30 am

2. Objectives
Definition
Inlet & its relations
Outlet & its relations
Boundaries
Contents
Defensive mechanism
Applied anatomy (hernias)

3. Before we start, lets look at :
Ant abdominal wall: It has 8 layers
1. Skin
2. Superficial fascia
3. Ext oblique muscle
4. Int oblique muscle
5. Transversus abdominis
6. Fascia transversalis
7. Extra peritoneal tissue
8. Parietal peritoneum

4. The normal structure of the
abdominal wall

5. Ext oblique
• ORIGIN
lower eight ribs
• INSERTION
Outer anterior half of iliac
crest, inguinal lig, public
tubercle and crest, and
aponeurosis of anterior rectus
sheath
• ACTION
Supports abdominal wall,
assists forced expiration, aids
raising intraabdominal
pressure and, with muscles of
opposite side, abducts and
rotates trunk
• NERVE
Anterior primary rami (T7-12)

6. Int oblique
• ORIGIN
Lumbar fascia, anterior two
thirds of iliac crest and lateral
two thirds of inguinal ligament
• INSERTION
Costal margin, aponeurosis of
rectus sheath (anterior and
posterior ), conjoint tendon to
pubic crest and pectineal line
• ACTION
Supports abdominal wall,
Conjoint tendon supports
posterior wall of inguinal canal
• NERVE
Anterior primary rami (T7-12)
(conjoint tendon ilioinguinal
nerve (L1))

7. Transversus abdominus
• ORIGIN
Costal margin, lumbar fascia,
anterior two thirds of iliac crest
and lateral half of inguinal
ligament
• INSERTION
Aponeurosis of posterior and
anterior rectus sheath and
conjoint tendon to pubic crest
and pectineal line
• ACTION
Supports abdominal wall, aids
forced expiration and raising
intra-abdominal pressure.
Conjoint tendon supports
posterior wall of inguinal canal
• NERVE
Anterior primary rami (T7-12).
Conjoint tendon ilioinguinal
nerve (L1)

8. Inguinal canal
Definition :
• It is a musculoaponeurotic tunnel extending from
superficial inguinal ring to the deep inguinal ring.
• The inguinal canal is about 4 cm long and is
directed obliquely and inferomedially through the
inferior part of the anterolateral abdominal wall.
• The canal lies parallel to the medial half of the
inguinal ligament.

10. Inguinal ligament:
• This ligament extends from the anterior
superior iliac spine to the pubic tubercle. It
is the lower free edge of the external
oblique aponeurosis.

11. Inlet of inguinal canal
• The inguinal canal has openings
• the deep and superficial inguinal rings.
The deep inguinal ring is the entrance to the inguinal canal.
• It is an oval gap in the transversalis fascia.
• It is about 1.25 cm superior to the middle of the inguinal
ligament.
• From the deep inguinal ring the vas deferens (or round
ligament of the uterus in the female), and gonadal
vessels pass to enter the inguinal canal.
• The transversalis fascia continues into the canal, forming
the innermost covering (internal fascia) of the structures
traversing the inguinal canal.

13. Outlet
• The superficial, or external inguinal ring is the
exit from the inguinal canal.
• It is a slitlike opening in the aponeurosis of the
external oblique muscle, superolateral to the
pubic tubercle.
• The medial and lateral margins of the superficial
ring formed by the split in the aponeurosis are
caller crura.
• The lateral crus is attached to the pubic tubercle
and the medial crus is attached to the pubic
crest.

15. • The anterior wall of the canal is formed mainly
by the aponeurosis of the external oblique with
the lateral part of the wall being reinforced by
fibres of the internal oblique.
• The posterior wall is formed by transversalis
fascia with the medial part of the wall being
reinforced by the conjoint tendon ( the merging
of the internal oblique and transversus
abdominal aponeurosis into a common tendon).

16. • The roof of the inguinal canal is formed by
the arching fibres of the internal oblique
and transverse abdominal muscles.
• The floor is formed by the superior surface
of the inguinal ligament. It is reinforced in
the medial part by the lacunar ligament (a
reflected part or extension from the deep
aspect of the inguinal ligament to the
pectineal line of the superior pubic ramus).

17. Contents
• The main content of the inguinal canal is
the spermatic cord in males and the round
ligament of the uterus in females.
• The canal also transmits the blood and
lymphatic vessels and the ilioinguinal
nerve L1.

18. Defensive mechanism(shutter
mechanism)
• The canal passes obliquely through the three
anterior abdominal muscles so the two rings are
at different positions. When intra abdominal
pressure is increased the canal closes like a flap
valve.
• The canal is protected by two of the anterior
abdominal muscles. The superficial ring is
protected posteriorly by the conjoint tendon. The
deep ring is posterior to the muscular fibres of
internal oblique.

19. • Arched fibres of internal oblique and
transversus act like demisphincters and
obliterate the canal by bringing the roof in
contact with the floor.
• Cremasteric plug: The cremaster muscle
contracts and pulls the testis towards the
superficial ring closing the outlet like a ball
valve.

20. Applied anatomy
• A hernia is a protrusion of tissue (usually parietal
peritoneum and viscera such as fat,gut or
omentum) through or alongside an opening in
the abdomen that is designed to allow a normal
structure to enter or exit.
Example: the deep inguinal ring may allow a
hernia to appear alongside the spermatic cord,
or in the femoral canal a hernia alongside the
lymphatics.

21. TYPES OF HERNIAS
• Indirect hernias arise
lateral to the inferior
epigastric vessels.
• Direct hernias arise
medial to the inferior
epigastric vessels

22. Other types of hernias ??

23. Causes ?

24. Indirect or oblique hernias
• This is the most common of all abdominal
hernias. It leaves the abdominal cavity lateral to
the inferior epigastric vessels and enters the
deep inguinal ring.
• The hernial sac is formed by a persistent
processus vaginalis and is surrounded by all
three fascial coverings of the spermatic cord.
• The hernia traverses the entire inguinal canal. It
exits through the superficial inguinal ring and
commonly enters the scrotum.

25. Indirect or oblique hernia entering
the scrotum

26. Direct hernias
• This is also known as acquired inguinal hernia.
• It is common in elderly men. The sac leaves the
abdominal cavity medial to the inferior epigastric
artery.
• It protrudes through an area of relative
weakness in the posterior wall of the inguinal
canal. The hernial sac is formed by transversalis
fascia. It lies outside the processus vaginalis,
which is usually obliterated, parallel to the
spermatic cord and outside the inner one or two
fascial coverings of the cord.

27. Direct hernias
• It does not traverse the entire inguinal canal.
• The hernia protrudes through the inguinal
triangle of Hesselbach that lies between the
inferior epigastric artery superolaterally, the
rectus abdominis medially and the inguinal
ligament inferiorly.
• It emerges through or around the conjoint
tendon to reach the superficial inguinal ring,
gaining an outer covering of external spermatic
fascia inside or parallel to that on the cord. It
almost never enters the scrotum.