- The abdominal musculaturehas three distinct layers that take three dif-
ferent directions. The external oblique muscle, internal oblique muscle,
and transverse abdominis muscle may be sequentially split and retracted
so that extensive suturing is unnecessary to provide a strong repair
(McBurney’s incision). - Because the linea albais relatively avascular, incisions may not heal well
and predispose to epigastric herniation. - Above the arcuate line,the anterior leaf of the rectus sheathis formed
by fusion of the external oblique and internal oblique aponeuroses; the
posterior leaf is formed by fusion of the internal oblique and transverse
abdominis aponeuroses. - Below the arcuate line,the anterior leaf of the rectus sheath is formed
by fusion of all three aponeuroses and there is no posterior leaf. - The inferior epigastric arterypasses into the rectus sheath at the arcuate
line. This is a potential site for spigelian herniation into the rectus sheath.
High-Yield Facts 53
ABDOMEN
Abdominal Wall
T4 Nipple
T7 Xiphoid process
T10 Umbilicus
L1 Inguinal ligament
DERMATOMAL LANDMARKS
Dermatome Region
Direct inguinal Through the inguinal triangle bounded by inguinal ligament,
inferior epigastric artery, and rectus abdominis—therefore, medial
to the inferior epigastric artery. Exits through the superficial
inguinal ring generally adjacent to the spermatic cord. Usually
acquired
Indirect inguinal Through the deep inguinal ring and along the inguinal canal—
therefore, lateral to the inferior epigastric artery. Exits through the
superficial ring within the spermatic cord. Usually congenital
Femoral Passes inferior to the inguinal ligament through the femoral ring
into the thigh. More prevalent in women
HERNIA CHARACTERISTICS
Hernia Pathway