this chapter discuss the surgical anatomy of inguinal canal of laparoscopic view

1. Surgical Anatomy of Inguinal canal
The anatomy of the inguinal region is not constant. Moreover,
the normal relationship of structures may be distorted by the very
process of herniation such that the appearance of surgery may vary
considerably from one patient to another. Nevertheless, an
appreciation of the usual anatomy of this region is fundamental to
successful hernia surgery, which is seen as a restitution of normal
abdominal wall morphology (Thomas, 1997).
General Description of the Anterior Abdominal Wall:
The anterior abdominal wall may be considered to have two
parts: an anterolateral portion composed of the external oblique,
internal oblique, and transversus abdominis muscles, and a midline
portion composed of the rectus abdominis and pyramidalis muscle
(Skandalakis, 2004).
Anterolateral portion:
The three flat muscles mentioned above are arranged so that
their fibers are roughly paralleled as they approach their insertion on
the rectus sheath (Condon, 1995).
Midline portion:
The linea Alba is a tendineous raphe extending from the
xiphoid process to the symphysis pubis and pubic crest. It lies
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Surgical Anatomy of Inguinal Canal

2. between the two recti and is formed by the interlacing and
decussating aponeurotic fibers of external oblique, internal oblique
and transversus abdominis. It is visible only in the lean and muscular
as a slight groove in the anterior abdominal wall. A fibrous cicatrix,
the umbilicus, lies a little below the midpoint of the linea Alba, and is
covered by an adherent area of skin. Below the umbilicus, the linea
Alba narrows progressively as the rectus muscles lie closer together.
Above the umbilicus, the rectus muscles diverge from one other and
the linea alba is correspondingly broader The linea alba has two
attachments at its lower end; its superficial fibers are attached to the
symphysis pubis, and its deeper fibers form a triangular lamella that
is attached behind rectus abdominis to the posterior surface of the
pubic crest on each side. This posterior attachment of linea Alba is
named the 'adminiculum lineae albae'. The linea alba is crossed from
side to side by few minute vessels (Cormack et al, 1994).
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Surgical Anatomy of Inguinal Canal

3. Figure (1) Normal anatomy of posterior wall of inguinal canal
(Skandalakis, 2004).
Internal and External Oblique Muscles :
The two most superficial abdominal wall muscles, namely, the
internal oblique muscle and external oblique muscle constitute the
anterior and lateral abdominal wall They probably only play a role in
modifying the direction of a hernial bulge, and are not felt to be
relevant in the etiology of inguinofemoral herniation. The lower most
part of the aponeurosis of the external oblique muscle forms the
inguinal (or Poupart's) ligament, which extends from the anterior
superior iliac spine laterally to the pubic tubercle medially. Medially,
some of its fibers rotate to insert into Cooper's ligament, forming the
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Surgical Anatomy of Inguinal Canal

4. lacunar ligament (of Gimbernat), but the distinction appears to be
clinically irrelevant (Desmond, 1997).
Transversus Abdominis Muscle:
The transversus abdominis muscle takes its origin from" lower
six ribs, the lumbodorsal fascia, the iliac crest, the iliopubic tract, and
the iliopsoas fascia. These fibers pass transversely around the lateral
abdomen to the midline. Lateral to the rectus abdominis, the fibers of
the transversus abdominis inserts into a tendinous aponeurosis. The
lower fibers cross downward And medially to form an aponeurotic
arch, which inserts at the pubic tubercle and the medial side of
Cooper's ligament, thus forming the superior, margin of the inguinal
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Surgical Anatomy of Inguinal Canal

5. Figure (2) Inguinal and femoral regions (Ferner and Staubesand, l974)
ring. Occasionally, these fibers join with parallel lower fibers of the
internal oblique muscle as they insert on the pubic tubercle and the
superior ramus of the pubis to form the so-called conjoined tendon.
This combination, however, has been found in only 3% to 5% of
cases. In fact, McVay and others have contended that the conjoined
tendon does not exist and is only an artifact of the dissection
(Desmond, 1997).
Direct and indirect herniation is prevented by an important
physiologic system known as the shutter mechanism. It is activated
by the simultaneous contraction of the internal oblique muscle and
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Surgical Anatomy of Inguinal Canal

6. transversus abdominis to approximate the transversus abdominis
aponeurotic arch to the iliopubic tract and the inguinal ligament, thus
reinforcing the posterior wall of the inguinal canal. In approximately
25% of individuals, the arch cannot descend enough to reach the
inguinal ligament. Sometimes, the arch is highly located or poorly
developed. In these cases, part of the deep wall lacks the
reinforcement of the aponeurotic arch and is supported only by the
fascia transversalis in the area of Hesselbach's triangle (Condon,
1995).
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Surgical Anatomy of Inguinal Canal

7. Cephalad to a line located approximately midway between the
umbilicus and the symphysis pubis (called the linea semicircularis of
Douglas), the aponeurotic fibers of the transversus abdominis pass
posterior to the rectus abdominis, thus contributing to the posterior
rectus sheath, whereas caudal to that level, they usually cross
anteriorly as part of the anterior rectus sheath. Consequently, only the
fascia transversalis and the peritoneum make up the posterior portion
of the rectus abdominis sheath caudal to the linea semicircularis. In a
minor number of cases, the aponeurotic lower portion of the
transversus abdominis does not end at the rectus abdominis sheath
but curves down to insert in to the superior ramus of the pubis. This
slip is defined by some as the falx inguinalis. According to others,
however, the term falx inguinalis should be reserved to indicate the
ligament of Henle, which is a vertical extension of the tendon of
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Surgical Anatomy of Inguinal Canal

8. rectus muscle (observed in 30% to 50% of patients) that attaches to
the symphysis pubis and Cooper's ligament (Condon, 1995).
Figure (3) External oblique muscle and aponeurosis (skin and layers of superficial
fascia removed). (Skandalakis, 2004).
The Anatomical Entities of the Groin:
Superficial fascia:
This fascia (described here only for the male) is divided into a
superficial part (Camper's) and a deep part (Scarpa's). The superficial
part extends upward on the abdominal wall and downward over the
pubis, scrotum, perineum, thigh and buttocks. The deep part extends
from the abdominal wall to the penis (Buck's fascia), the scrotum
(dartos), and the perineum (Colles1
fascia) (Skandalakis, 2004).
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Surgical Anatomy of Inguinal Canal

9. Aponeurosis of the external oblique muscle:
Below the arcuate line (Linea Semicircularis of Douglas Which
marks the level at which the rectus sheath lose its posterior wall), this
aponeurosis joins with the aponeuroses of the internal oblique and
transversus abdominis muscles to form the anterior layer of the rectus
sheath. This aponeurosis forms or contributes to three anatomical
entities in the inguinal canal.
• Inguinal ligament (Poupart's)
• Lacunar ligament (Gimbernat's)
• Reflected part of inguinal ligament (Colles's)
(Included sometimes in the pectineal ligament (Cooper's),
which is also formed from tendinous fibers of the internal oblique,
transversus, and pectineus muscles) (Condon, 1995).
Figure (4) Parasagittal section through right mid-inguinal region, illustrating
separation of musculoaponeurotic lamina into anterior and posterior inguinal
walls. (Skandalakis, 2004).
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Surgical Anatomy of Inguinal Canal

10. Inguinal Ligament (Poupart's):
The inguinal ligament is the thick, inrolled lower border of the
aponeurosis of external oblique and stretches from the Anterior
superior iliac spine laterally, to the pubic tubercle medially. Its
grooved abdominal surface forms the floor of inguinal canal. The
lateral half is rounded and lies more obliquely than the medial half.
The latter gradually widens towards its attachment to the pubis,
where it becomes more Horizontal and supports the spermatic cord.
At the medial end, some fibers do not attach to the pubic tubercle but
extend in two directions). Some expand posteriorly and laterally to
attach to the pictineal line, forming the lacunar ligament complex.
Other fibers pass upwards and medially behind the superficial
inguinal ring and external oblique to join the rectus sheath and the
linea Alba. These constitute the reflected part of the inguinal
ligament. Fibers from either side decussate in the linea Alba, similary
to the aponeurosis of the abdominal muscles (Condon, 1995).
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Surgical Anatomy of Inguinal Canal

11. Figure (5) "Conjoined area (Skandalakis, 2004).
Lacunar ligament (Gimbernat's):
The lacunar ligament is a thick triangular band of tissue lying
mainly posterior to the medial end of the inguinal ligament. It
measures 2 cm from base to apex and is a little larger in the male. It
is formed from fibres of the medial end of the inguinal ligament and
fibres from the fascia lata of the thigh, which join the medial end of
the inguinal ligament from below. The inguinal fibres run posteriorly
and laterally to the medial end of the pectineal line and are
continuous with the pectineal fascia they form a near horizontal,
triangular sheet with a curved medial border. This edge forms the
medial border of the femoral canal. The apex of the triangle is
attached to the pubic tubercle. A strong fibrous band, the pectineal
ligament of Astley Cooper, extends laterally along the pectineal line
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Surgical Anatomy of Inguinal Canal

12. from the pectineal attachment. The fibers from the fascia lata join the
inferoposterior border of the inguinal ligament, which, in
combination with fibers from the transversalis fascia, fuses with the
pectineal fascia as it joins the thickened periosteum of the pectineal
line. This portion of the lacunar ligament forms the lower extension
of the medial border of the femoral canal and femoral sheath (Lytle,
1979).
Pectineal Ligament (Cooper's):
This is a thick, strong tendineous band formed principally by
tendinous fibers of the lacunar ligament and aponeurotic fibers of the
internal oblique, transversus abdominis, and pectineus muscles and,
with variations, the inguinal falx. It is fused to the periosteum of the
ilium. The tendinous fibers are lined internally by transversalis fascia
(Skandalakis, 2004)
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Surgical Anatomy of Inguinal Canal

13. .
Figure (6) Iliopectineal arch. (Skandalakis, 2004).
The Inguinal Canal:
The canal is an oblique intermuscular space that extends from
the deep to superficial inguinal rings and transmits the spermatic cord
in males, and round ligament in females. Most of the canal consists
of the aponeurosis of the external oblique as it curves inwards to
form the inguinal ligament. In the lateral portion of the canal, the
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Surgical Anatomy of Inguinal Canal

14. lower fibers of internal oblique also contribute as they pass up and
over the cord, forming, with transversus abdominis, the roof of the
canal. The deep aspect, or posterior wall, of the canal, comprises the
transversalis fascia, which is strengthened medially by the falx
inguinalis or edge of rectus, more laterally there is support from the
transversus abdominis arch and its aponeurosis. The weak area
between the supporting ligamentous structures is at risk of direct
herniation. The inferior border of the canal is formed by the rolled
fibers of inguinal ligament medially, and then the pectineus fascia
and the insertion of the lacunar ligament (Thomas, 1997).
Superficial inguinal ring:
The superficial inguinal ring is a hiatus in the aponeurosis of
external oblique, just above and laterals to the crest of the pubis. The
ring is actually triangular, and its apex points along the line of the
deep fibers of the aponeurosis. Although it varies in size, it does not
usually extend laterally beyond the medial one-third of the inguinal
ligament. The base lies along the crest of the pubis and its sides are
the crura of the opening the aponeurosis. The lateral cru is the
stronger and is reinforced by fibers of the inguinal ligament inserted
into the pubic tubercle. The medial crus is thin. The fibers attach to
the front of the symphysis pubis and interlace with fibers from the
opposite side in the external layer of the investing fascia of external
oblique, some fibers arch above the apex of the superficial inguinal
ring as intercrural fibres. In the male, the lateral crus is curved to
form a groove, in which the spermatic cord passes. Fibers from the
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Surgical Anatomy of Inguinal Canal

15. aponeurosis of external oblique and overlying fascia continue
downwards from the crura of the ring, and form a delicate tubular
prolongation of fibrous tissue around the spermatic cord and testes.
This is the external spermatic fascia and constitutes the outermost
covering of the cord. The superficial inguinal ring is only a distinct
aperture when the continuity of this fascia with the aponeurosis
interrupted. The ring is smaller in females (Rizk, 1980).
Deep inguinal ring:
The deep inguinal ring is situated in the transversalis fascia,
midway between the anterior superior iliac spine and the symphysis
pubis 1.25 cm above the inguinal ligament. It is oval, with an almost
vertical long axis. Its size varies between individuals, and it is always
much larger in males. It is related above to the arched lower margin
of transversus abdominis, and medially to the inferior epigastric
vessels. Traction on the fascial ring exerted by internal oblique may
constitute a valve-like safety mechanism when intra-abdominal
pressure is increased (Rizk, 1980).
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Surgical Anatomy of Inguinal Canal

16. (Ferner and Staubesand, l974)
Figure (7) Inguinal region
The inferior epigastric vessels are important posterior relations
of the medial end of the canal. They lie on the transversalis fascia as
they ascend obliquely behind the conjoint tendon into the posterior
portion of the rectus sheath. The inguinal triangle lies in the posterior
wall of the canal. It is bounded inferiorly by the medial half of the
inguinal ligament, medially by the lower lateral border of rectus
abdominis and laterally by the inferior epigastric artery. It overlies
the medial inguinal fossa and, in part, the supravesical fossa (Lytle,
1979).
The spermatic cord:
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Surgical Anatomy of Inguinal Canal

17. In men the vas deferens, testicular artery and vein, cremasteric
blood vessels and lymphatics traverse the abdominal wall picking up
musculo-fascial coverings to emerge at the superficial inguinal ring
as the spermatic cord. The transversalis fascia contributes the internal
spermatic fascia, the transversus and internal oblique form the
cremasteric muscle layer, and the external oblique forms the external
spermatic fascia.
The cord also contains the genital branch of the genitofemoral
nerve, which supplies cremasteric muscle and is sensory to the tunica
vaginalis and spermatic fasciae. The ilio-inguinal nerve emerges from
the lower border of the internal oblique muscle and runs deep to the
external oblique aponeurosis on the front of the cord to emerge from
the superficial ring (Thomas, 1997).
Maintenance of the blood supply to the testicle is clearly of
importance if the complication of testicular atrophy is to be avoided.
The principle blood supply of the testicle is from the testicular artery,
which arises from the aorta or renal artery, but the testicle also
receives important contribution from both the cremasteric artery,
which arises from the inferior epigastric artery, and the artery to the
vas deferens, a branch of the superior vesicle artery. A rich collateral
circulation exists with other perineal structures such as the prostate
and scrotum (Heifetz, 1997).
In order to minimize the risk of atrophy, this collateral
circulation must be conserved by ensuring that the testicle is never
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Surgical Anatomy of Inguinal Canal

18. mobilized from the scrotum. In the absence of arterial disruption, it
would seem likely that the main cause of atrophy following hernia
repair is venous congestion. The testicular and epididymal veins
emerge posteriorly and form the pampiniform plexus; within the
abdomen, the plexus drain into the testicular veins which pass
upwards in the retroperitoneal space to enter the inferior vena cava on
the right and the renal vein in the left (Thomas, 1997).
Hesselbach's triangle:
The inguinal (Hesselbach's) triangle is a weak area of the groin.
As described by Hesselbach's in 1814, the base of triangle was
formed by the pectineal Cooper's ligament. The other borders of the
triangle are: the inferior eigastric vessels superio-laterally, and the
lateral border of the rectus sheath medially.
These borders have subsequently been modified with the
substitution of the inguinal ligament for Cooper's ligament, to allow
an easier identification of the area by surgeons who use the
traditional anterior approach for herniorrhaphy. For the laparoscopic
procedure, however, it seems more appropriate to return to
Hesselbach's original description since the inguinal ligament is not
visible laparoscopically. The inferior portion of the triangle includes
the weak area seen in the medial umbilical fossa, where direct hernia
develops; its boundaries are the apneurotic arch superiorly and the
iliopubic tract inferiorly (Annibali and Fitzgibbons, 1995).
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Surgical Anatomy of Inguinal Canal

19. (Ferner and Staubesand, l974)
Figure (8) Inguinal canal and spermatic cord
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Surgical Anatomy of Inguinal Canal