CDIS 4213 Lecture Notes - Lecture 6: Central Tendon Of Diaphragm, Costal Margin, Lumbar Vertebrae
14 Sep 2016
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Document Summary
Quiet resting breathing requires active muscle contraction during inhalation, but not during exhalation: elastic nature of lungs. Average respiratory cycle for an adult is 12x per minute. This is just during every day life, not doing anything strenuous. When more air is required to exhale (e. g. , blowing out candle), muscle contraction will happen. Muscles of inhalation mainly in thorax: accessory muscles in neck and thoracic enlargement. Originates at lower portion xyphoid process (little point at the bottom of the sternum) Shortest fibers are in this part of diaphragm. Xyphoid process is different from manubrium and body because it can only turn to bone over time. Fibers interdigitate (intertwine your fingers) with transverse abdominis muscles. Vertebral portion (vertebral muscles are sometimes called lateral vertebral muscles) Encircles esophagus by means of other muscle pillars before entering central tendon: mechanics of diaphragm. Downward and forward movement of central tendon causes increase in size of thoracic cavity, and decrease in lug pressure, enabling inhalation.
