Anterolateral Abdominal Wall Flashcards
What are the 3 muscle layers of the anterolateral abdominal wall - list them in order from superficial to deep.
External oblique, internal oblique and transversus abdominis.
What is the orientation of their fibers?
External oblique are directed inferior and medially (hands-in-pockets); internal oblique go upward and medially (opposite to the externals), and the transversus abdominis are oriented transversely.
Which attach posteriorly to the lumbar fascia?
The internal oblique and the transversus abdominis are attached posteriorly to the lumbar fascia.
What is the innervation of these muscle layers?
Intercostal nn. (referred to a thoracoabdominal nn. as they extend from the intercostal space down into the abdominal musculature.
How does each layer of the anterior abdominal wall contribute to the formation of
the rectus sheath above the level of the umbilicus?
Above the umbilicus: the anterior sheath of the rectus is composed of the aponeurosis of the external oblique and half the aponeurosis of the internal oblique; the posterior sheath of the rectus is composed of the other half of the aponeurosis of the internal oblique and the aponeurosis of the transversus abdominis.
What is the arcuate line?
The discontinuance of the posterior sheath of the rectus - approximately the level of L2.
What forms the posterior aspect of the rectus sheath below this line?
Only the fascia transversalis and peritoneum.
Where does the inferior epigastric artery arise?
External iliac artery.
Where does the inferior epigastric artery run within the rectus sheath?
Between the posterior sheath and posterior aspect of the rectus abdominis muscle.
How does the inferior epigastric artery pass the tendinous intersections of the rectus
abdominis?
The tendinous intersection of the rectus abdominis only attach to the anterior sheath of the rectus so the pathway up the posterior aspect is unimpeded.
With what vessel does the inferior epigastric artery anastomose?
With the superior epigastric artery (one of the terminal br. of the internal thoracic artery).
What action results from the ipsilateral contraction of the anterolateral wall muscles?
Lateral trunk flexion.
What action results from the contralateral contraction of this group?
Torsion/twisting of the trunk.
Why is compression of the abdominal contents functionally important?
To increase intra-abdominal pressure to facilitate defecation/micuration (urination).
Which muscles are involved in quiet inspiration and which diameters of the thorax
do they increase?
The intercostal mm. elevate the ribs increasing the transverse and anteroposterior diameters.
