Anterolateral Abdominal Wall Flashcards
What are the 3 muscle layers of the anterolateral abdominal wall (superficial to deep)?
External oblique, internal oblique and transversus abdominis.
What is the orientation of fibers of the anterolateral abdominal wall?
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 mm. attach posteriorly to lumbar fascia? What muscle is not?
The internal oblique and the transversus abdominis are attached posteriorly to the lumbar fascia. The external oblique is NOT.
What is the innervation of these muscle layers?
They are innervated segmentally by the anterior/ventral rami of the spinal/intercostal nn. (referred to as 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 ANTERIOR rectus sheath above the level of 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
How does each layer of the anterior abdominal wall contribute to the formation of the POSTERIOR rectus sheath above the level of the umbilicus?
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 forms the arcuate line? At what spinal level?
The discontinuance of the posterior sheath of the rectus - approximately the level of L2.
What forms the posterior aspect of the rectus sheath BELOW the arcuate line?
Only the fascia transversalis and peritoneum.
From 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).
