Diaphragm – Definition, Function, Muscle & Anatomy | Kenhub


Hey there! It’s Matt from Kenhub, and in
this tutorial, we will discuss the diaphragm. The diaphragm is a skeletal muscle that resides
in the trunk of the body and separates the thoracic and abdominal cavities from one another.
Its function occurs during breathing when it contracts to enlarge the thoracic cavity
and reduce the intrathoracic pressure so that the lungs may expand and fill their alveoli
with air. The diaphragm’s superior origin is continuous
from the xiphoid process anteriorly to the lower six costal cartilages of the thorax
laterally and the first 2/3 lumbar vertebrae posteriorly. The musculoskeletal fibers radiate
from all angles towards the center of the body and converged into a central tendon which
is the inferior attachment or muscular insertion point. It is innervated by the phrenic nerve
which arises from the fibers of the 3rd to the 5th cervical spinal root ganglia. It draws
the central tendon anteriorly and inferiorly during inspiration. The diaphragm has several openings in its
dome which allows structures to pass between the thoracic and abdominal cavities. There
are 3 major openings and 5 minor openings. The major openings are named after the largest
structures that run through them and are the aortic hiatus which allows the aorta, the
azygos vein, and the thoracic duct to pass from the thoracic cavity into the abdomen;
the esophageal hiatus which contains the esophagus and the esophageal arteries as well as the
anterior and posterior vagal trunks, and the vena caval foramen which of course encircles
the inferior vena cava as well as some of the branches of the right phrenic nerve. The minor openings and their structures are:
The lesser aperture of the right crus that houses the greater and lesser right splanchnic
nerves, the lesser aperture of the left crus contains the greater and lesser left splanchnic
nerves and the hemiazygos vein, the sympathetic trunk runs behind the diaphragm under the
medial lumbocostal arches, the Foramen of Morgagni which is found in the areolar tissue
between the sternal and costal parts of the diaphragm contains the superior epigastric
branch of the internal thoracic artery and the lymphatics of the abdominal wall that
sit on the convex surface of the liver, and the medial and lateral lumbocostal arches
contain areolar tissue that when present separates the superior and posterior surface of the
kidney from the pleura. This video is more fun than reading a textbook,
right? If you want more videos, interactive quizzes, articles, and an atlas of human anatomy,
click on the “Take me to Kenhub” button. It is time to say goodbye to your old textbooks
and say hello to your new anatomy learning partner, Kenhub! See you there! https://www.kenhub.com

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