4. INGUINAL CANAL
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.
Length and direction: It is about 4 cm long, and is
directed downwards, forwards and medially.
The inguinal canal extends from:-
The deep inguinal ring to the superficial inguinal ring.
5. .
• The deep inguinal ring is an oval opening in the
fascia transversalis, situated 1.2 cm above the
midinguinal point.
• The superficial inguinal ring is a triangular gap in
the external oblique aponeurosis.
• The base is formed by the pubic crest. Lateral/
lower margin, medial/ upper margin of the
triangle.
• It is 2.5 cm long and 1.2 cm broad at the base.
These margins are referred to as crura.
6. (a) Superficial and deep inguinal rings, (b) formation of the roof of inguinal
canal, and (c) anterior and posterior walls of inguinal canal
9. (a) Superficial and deep inguinal rings, (b) formation of the roof of inguinal
canal, and (c) anterior and posterior walls of inguinal canal
10. Structures passing through the inguinal canal
In males
• Spermatic cord
• Ilioinguinal nerve
In females
• Round ligament of uterus
• Ilioinguinal nerve
Sex Difference
The inguinal canal is larger in
males than in females
11. Constituents of the Spermatic Cord
1. The ductus deferens.
2. The testicular and cremasteric arteries, and the artery of
the ductus deferens.
3. The pampiniform plexus of veins.
4. Lymph vessels from the testis
5. The genital branch of the genitofemoral nerve, and the
plexus of sympathetic nerves around the artery to the
ductus deferens and visceral afferent nerve fibres.
6. Remains of the processus vaginalis.
13. Coverings of Spermatic Cord
1. The external spermatic fascia
• derived from the external oblique
2.The cremasteric fascia and muscles:-
• derived from the internal oblique & transversus abdominis
3. The internal spermatic fascia:-
• derived from the fascia transversalis
• Covers the cord in its whole length
15. MECHANISM OF INGUINAL CANAL
• The presence of the inguinal canal is a cause of
weakness in the lower part of the anterior
abdominal wall.
• This weakness is compensated by :-
1. Obliquity of the inguinal canal: the two rings do not
lie opposite to each other. When the intra
abdominal pressure rises the anterior & posterior
walls of the canal are approximated, thus
obliterating the passage.
Known as FLAP VALVE mechanism
16. 2. The superficial inguinal ring is guarded from behind
by the conjoint tendon
3. The deep inguinal ring is guarded from the front by
the fleshy fibres of the internal oblique
4. 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.
17. 5. Contraction of the cremaster helps the spermatic
cord to plug the superficial inguinal ring (ball valve
mechanism).
6. Contraction of the external oblique and its
intercrural fibres results in approximation of the
two crura of the superficial inguinal ring (slit valve
mechanism).
When there is rise in intra abdominal pressure as in
coughing, sneezing, lifting heavy weights all these
mechanisms come into play, so that the inguinal
canal is obliterated, its openings are closed and
herniation of abdominal viscera is prevented.
18. CLINICAL ANATOMY
Hernia is a protrusion of any of the abdominal contents
through any of its walls. This is called external hernia.
At times the intestine or omentum protrudes into the
“no entry” zone within the abdominal cavity itself. The
condition is called as internal hernia.
19. Hernia consists of sac, contents and coverings.
1. Sac is the protrusion of the
peritoneum
• neck, the narrowed part;
• body,
• bigger part.
2. Contents are mostly long
mobile, keen to move out,
coils of small intestine or any
other viscera
3. Coverings: layers of
abdominal wall which are
covering the hernial sac.
20. Complications
1. Irreducibility:- the loop of the intestine herniates
out but comes back to the abdomen. Sometime,
the loop goes out but does not return, leading to
irreducible hernia.
2. Obstruction:- the loop may get narrow, so that
contents of the loop cannot move, leading to
obstruction.
3. Strangulation:- when the arterial supply is
blocked, the loop gets necrosed.
25. Femoral hernia
it occurs more in female, due to larger pelvis, smaller blood vessels & larger femoral
canal
26. Inguinal hernia: protrusion of the loop of intestine through the
inguinal wall or inguinal canal.
Indirect/ oblique inguinal hernia
when the protrusion occurs
through the deep inguinal
ring, inguinal canal,
superficial inguinal ring into
the scrotum.
Occurs in male infants,
children &
has narrow neck of the
hernial sac
Direct inguinal hernia
when the protrusion occurs
through the weak posterior
wall of the inguinal canal/
triangle of Hesselbach
Occurs in much older men
Has wider neck of hernial sac
Divided into medial & lateral
parts by the passage of
obliterated umbilical artery
27. • Epigastric hernia:
• It occurs through the
upper part of wide linea
alba
• Divartication of recti:
• Occurs in multiparous
(given birth more than
once) female, with
weak anterolateral
abdominal muscles
