The diaphragm
Introduction
Diaphragm may refer to any of the following:-
Thoracic diaphragm, a sheet of muscle separating the thorax and abdomen of mammals
Urogenital diaphragm, a layer of the pelvis separating deep perineal sac from the upper pelvis
Pelvic diaphragm, a pelvic muscle consisting of the Levator ani and the Coccygeus
Thoracic Diaphragm - dome-shaped musculofibrous septum
It separates the thoracic from the abdominal cavity
Convex upper surface forms the floor of the thoracic cavity
Concave under surface forms the roof of the abdominal cavity.
Peripheral part consists of muscular fibers which take origin from the circumference of the thoracic outlet Converge to be inserted into a central tendon.
The muscular fibers may be grouped according to their origins into three parts:
Parts of diaphragm
sternal part: origin : two fleshy slips from the back of the xiphoid process.
costal part origin : the inner surfaces of the cartilages and adjacent portions of the lower six ribs on either side, interdigitating with the Transversus abdominis.
lumbar part: origin : aponeurotic arches, named the lumbocostal arches, and from the lumbar vertebrae by two pillars or crura.
There are two lumbocostal arches, a medial and a lateral, on either side.
Nerve supply
The diaphragm is innervated by the phrenic nerve.
Openings in the Diaphragm
Three large openings
Caval opening level : T8 : inferior vena cava, and some branches of the right phrenic nerve
Esophageal hiatus : level : T10 esophagus, the vagus nerves, and some small esophageal arteries
Aortic hiatus : T12 : the aorta, the azygos vein, and the thoracic duct
Two lesser apertures : of right crus greater and lesser right splanchnic nerves
three lesser aperture : of left crus greater and lesser left splanchnic nerves and the hemiazygos vein
Blood supply
Pericardiacophrenic artery, Musculophrenic artery, Inferior phrenic arteries
Vein Superior phrenic vein, Inferior phrenic vein
Nerve supply
Phrenic nerve and lower intercostal nerves
Action
To assist in the respiration (inspiratin) by contracting and increasing the volume of the thoracic cage
Applied anatomy
Hiatal hernia - near the gastroesophageal junction.
A hiccup occurs when the diaphragm contracts periodically without voluntary control.
Gas under the diaphragm may be pneumoperitoneum.
