AnatomyLesson 1 of 1 in the course The Muscular System

Anterolateral Abdominal Wall, Respiratory Muscles, and Pelvic Floor

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Four paired muscles cover the anterior and lateral abdominal region: the external obliques, internal obliques, transversus abdominis, and rectus abdominis. The first three are broad, flat layers whose fibers run in different directions. This layered arrangement permits trunk movement and helps protect organs in a region without a bony covering.

The external oblique is the most superficial of the three flat muscles. Its fibers run inferiorly and medially, like fingers sliding into pants pockets. Beneath it, the internal oblique has fibers that run superiorly and medially, roughly in the direction of thumbs placed in those pockets. Acting together, the obliques can flex the trunk; acting on one side, they can contribute to lateral flexion and rotation.

All flashcards

Which four paired muscles form the anterolateral abdominal wall?
External obliques, internal obliques, transversus abdominis, and rectus abdominis.
What is the linea alba?
A white fibrous band where the right and left rectus sheaths meet at the anterior midline.
What is the Valsalva maneuver?
A held diaphragmatic contraction coordinated with abdominal muscle contraction to increase abdominal pressure.
What forms the pelvic diaphragm?
The levator ani and ischiococcygeus muscles.
What are the boundaries of the perineum?
The pubic symphysis anteriorly, coccyx posteriorly, and ischial tuberosities laterally.

Quiz questions

  1. How do the external intercostal muscles assist inspiration?Answer: They elevate the ribs and expand the rib cage.
  2. Which structures pass through the aortic hiatus of the diaphragm?Answer: The aorta, thoracic duct, and azygos vein.
  3. During the Valsalva maneuver, what combination of muscle activity raises abdominal pressure?Answer: A held diaphragmatic contraction coordinated with abdominal muscle contraction.
  4. Which muscles make up the pelvic diaphragm?Answer: The levator ani and ischiococcygeus.
  5. Which structures are found in the posterior and anterior triangles of the perineum, respectively?Answer: The anus in the anal triangle and external genitals in the urogenital triangle.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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