Download Anterior wall

Dr. Mohamed Ahmad Taha Mousa
Assistant Professor of Anatomy and Embryology
Objectives
a. Discuss inguinal canal and its contents
b. Discuss the rectus sheath and its contents
c. Identify clinical applications (Abdominal
incisions, extravasations of urine, abdominal and
inguinal hernia)
Inguinal canal
- It is oblique passage through the lower
part of the anterior abdominal wall.
- It is about 1.5 inch long in adult and
extends from the deep inguinal ring to
the superficial inguinal ring.
Deep inguinal ring: It is oval opening in
the fascia transversalis.
- It lies about 0.5 inch above the
midinguinal point.
- The margins of the ring give attachment
to the internal spermatic fascia.
Superficial inguinal ring: It is triangular
shaped opening in the aponeurosis of the
external oblique muscle.
- It lies above and medial to the pubic
tubercle.
- The margins of the ring called the crura
and give attachment to the external
spermatic fascia.
Walls of the Inguinal canal
Posterior wall
Deep inguinal ring
Anterior wall:
Fascia transversalis
- Medially: External oblique aponeurosis.
Conjoint tendon
- Laterally: External oblique and origin of the
internal oblique from the inguinal ligament.
Lateral
Internal oblique
- The lateral part is the strongest where it
lies opposite the weakest part of the
Medial
External oblique
posterior wall (deep inguinal ring).
Superficial inguinal ring
Posterior wall:
Anterior wall
- Medially: Conjoint tendon and fascia
transversalis.
- Laterally: The fascia transversalis.
- The medial part is the strongest where it
lies opposite the weakest part of the
anterior wall (superficial inguinal ring).
Roof: Arching fibers of the internal oblique
and transversus abdominis muscles.
Floor: The inguinal ligament and at its medial
end, the lacunar ligament.
Function of the Inguinal canal
In male:
- It is the passage for the spermatic cord from
the testis to the abdomen
- Ilioinguinal nerve.
In the female:
- It is the passage for the round ligament of
the uterus from the uterus to the labium
majora.
- Ilioinguinal nerve.
Mechanics of the Inguinal Canal
- It is the site of potential weakness in the
anterior abdominal wall in both sexes.
- The design of the inguinal canal decrease
this weakness by:
1. The canal is an oblique passage: The
weakest areas the superficial and deep
inguinal rings lying a way from each others.
2. The anterior wall: It is reinforced by the
fibers of the internal oblique muscle in front
of the deep inguinal ring.
3. The posterior wall: It is reinforced by the
strong conjoint tendon behind the
superficial inguinal ring.
Posterior wall
Deep inguinal ring
Fascia transversalis
Conjoint tendon
Lateral
Internal oblique
Medial
External oblique
Superficial inguinal ring
Anterior wall
4. On coughing and straining (in micturition,
defecation and parturition):
The arching fibers of the internal oblique and
transversus abdominis muscles contracts
leading to flattening of the roof.
- The roof actually compress the contents of
the canal against the floor so that the canal
is virtually closed.
5. When great straining efforts may be
necessary : The person naturally assume the
squatting position so the lower part of the
anterior abdominal wall is protected by the
thighs.
Regions of the abdomen
Rectus sheath
- It is the fibrous sheath that envelopes the rectus
abdominis and pyramidalis muscle.
- It is formed by the aponeurosis of the three
lateral abdominal muscles.
The rectus sheath is divided into 3 parts:
1. Above the costal margin:
Anterior wall: It is formed by the aponeurosis of
the external oblique muscle.
Posterior wall: It is formed by the 5th , 6th and
7th costal cartilages and the intercostal spaces.
2. Between the costal margin and the level of
the anterior superior iliac spine:
The aponeurosis of internal oblique splits into 2
lamellae.
Anterior wall: It is formed by the aponeurosis of
the external oblique and anterior lamellae of
internal oblique.
Posterior wall: It is formed by the posterior
lamellae of internal oblique and the transversus
abdominis muscle.
3. Between the level of the anterior superior
iliac spine and the pubis:
Anterior wall: It is formed by the aponeurosis of
all three muscles.
Posterior wall: It is absent and the rectus
abdominis muscle lies in contact with the fascia
transversalis.
- At the level of the anterior superior iliac spine the
posterior wall form the arcuate line.
- At this site the inferior epigastric vessels enter
the rectus sheath and pass upward to anastomosis
with the superior epigastric vessels.
Contents of the rectus sheath
a. Muscles:
1. Rectus abdominis muscle.
2. Pyramidalis muscle.
b. Blood vessels:
1. Superior epigastric vessels.
2. Inferior epigastric vessels.
c. Nerves:
1. Lower 5 intercostal nerves.
2. Subcostal nerve.
Clinical application
a. Surgical incisions: It should be made in
parallel lines with the bundles of collagen
fibers.
- It heals as a narrow scar, whereas one that
crosses the lines heals as wide scars.
b. Extravasations of urine: Rupture of the
penile urethra followed by extravasations of
urine into the scrotum, perineum and penis
and then up into the lower part of the anterior
abdominal wall deep to the membranous layer
of fascia. The passage of urine to the thigh is
prevented by attachment of the membranous
layer to the fascia lata of the thigh.
c. Hematoma of the rectus sheath: It occurs
on the right side below the umbilicus and
causes abdominal pain. The source of bleeding
is the inferior epigastric vein or artery.
- It occurs during severe cough or blunt trauma.
d. Abdominal hernia: It is the protrusion of
part of the abdominal contents through the
anterior abdominal wall.
Types of hernia: - Inguinal (indirect or direct)
- Femoral
- Umbilical
- Epigastric
- Incisional
Indirect inguinal hernia: It is the most
common congenital hernia.
The hernial sac enters the inguinal canal
lateral to the inferior epigastric vessels down
into the scrotum or labium majora.
- It is about 20 times more common in males
than in females.
Direct inguinal hernia: The hernial sac bulges
directly through the posterior wall of inguinal
canal medial to the inferior epigastric vessels.
Femoral hernia: It descends through the
femoral canal within the femoral sheath.
Thank you