The diaphragm: two physiological muscles in one

Abstract

To the respiratory physiologist or anatomist the diaphragm muscle is of course the prime mover of tidal air.However, gastrointestinal physiologists are becoming increasingly aware of the value of this muscle in helping to stop gastric contents from refluxing into the oesophagus. The diaphragm should be viewed as two distinct muscles, crural and costal, which act in synchrony throughout respiration. However, the activities of these two muscular regions can diverge during certain events such as swallowing and emesis. In addition, transient crural muscle relaxations herald the onset of spontaneous acid reflux episodes. Studying the motor control of this muscular barrier may help elucidate the mechanism of these episodes. In the rat, the phrenic nerve divides into three branches before entering the diaphragm, and it is possible to sample single neuronal activity from the crural and costal branches.This review will discuss our recent findings with regard to the type of motor axons running in the phrenic nerve of the rat. In addition, we will outline our ongoing search for homologous structures in basal vertebrate groups. In particular, the pipid frogs (e.g. the African clawed frog, Xenopus laevis ) possess a muscular band around the oesophagus that appears to be homologous to the mammalian crural diaphragm. This structure does not appear to interact directly with the respiratory apparatus, and could suggest a role for this region of the diaphragm, which was not originally respiratory.

Muscles of Breathing: Development, Function, and Patterns of Activation

“…Isolated stimulation of the crural diaphragm also increases abdominal pressure and dimensions, but does not expand the rib cage (114). These observations suggest that the two parts of the diaphragm are both anatomically and functionally distinct, consistent with their different embryologic origins (243) and that the crural diaphragm is devoted mainly to digestive functions (346).…”

Muscles of Breathing: Development, Function, and Patterns of Activation

“…Isolated stimulation of the crural diaphragm also increases abdominal pressure and dimensions, but does not expand the rib cage (114). These observations suggest that the two parts of the diaphragm are both anatomically and functionally distinct, consistent with their different embryologic origins (243) and that the crural diaphragm is devoted mainly to digestive functions (346).…”

Esophageal balloon dilation in children: prospective analysis of hemodynamic changes and complications during general anesthesia

“…A number of investigations show that esophageal distension reflexively alters the pattern of ventilation and distribution of motor activity to the respiratory muscle [6][7][8]. It was reported that balloon dilation could be done safely with sedation [9,10].…”

Effectiveness of Abdominal breathing exercise to control Gastroesophageal Reflux Disease, a randomized controlled trial

“… 20 These are innervated independently as a striated muscle that contracts during breathing. 21 This led to our hypothesis that by actively training the diaphragm by abdominal breathing exercises, the gastric acid reflux and symptoms of GERD can be decreased. This intervention showed an improvement in acid reflux symptoms and PPI usage.…”

Muscles of Breathing: Development, Function, and Patterns of Activation

“…Isolated stimulation of the crural diaphragm also increases abdominal pressure and dimensions, but does not expand the rib cage (114). These observations suggest that the two parts of the diaphragm are both anatomically and functionally distinct, consistent with their different embryologic origins (243) and that the crural diaphragm is devoted mainly to digestive functions (346).…”

Esophageal balloon dilation in children: prospective analysis of hemodynamic changes and complications during general anesthesia

“…A number of investigations show that esophageal distension reflexively alters the pattern of ventilation and distribution of motor activity to the respiratory muscle [6][7][8]. It was reported that balloon dilation could be done safely with sedation [9,10].…”

Effectiveness of Abdominal breathing exercise to control Gastroesophageal Reflux Disease, a randomized controlled trial

“… 20 These are innervated independently as a striated muscle that contracts during breathing. 21 This led to our hypothesis that by actively training the diaphragm by abdominal breathing exercises, the gastric acid reflux and symptoms of GERD can be decreased. This intervention showed an improvement in acid reflux symptoms and PPI usage.…”

Muscles of Breathing: Development, Function, and Patterns of Activation

“…Isolated stimulation of the crural diaphragm also increases abdominal pressure and dimensions, but does not expand the rib cage (114). These observations suggest that the two parts of the diaphragm are both anatomically and functionally distinct, consistent with their different embryologic origins (243) and that the crural diaphragm is devoted mainly to digestive functions (346).…”

Esophageal balloon dilation in children: prospective analysis of hemodynamic changes and complications during general anesthesia

“…A number of investigations show that esophageal distension reflexively alters the pattern of ventilation and distribution of motor activity to the respiratory muscle [6][7][8]. It was reported that balloon dilation could be done safely with sedation [9,10].…”

Effectiveness of Abdominal breathing exercise to control Gastroesophageal Reflux Disease, a randomized controlled trial

“… 20 These are innervated independently as a striated muscle that contracts during breathing. 21 This led to our hypothesis that by actively training the diaphragm by abdominal breathing exercises, the gastric acid reflux and symptoms of GERD can be decreased. This intervention showed an improvement in acid reflux symptoms and PPI usage.…”