bulb is the part of the digestive tract that runs through the diaphragm.
bulb is the part of the digestive tract that runs through the diaphragm.
which part of the digestive tract runs through the diaphragm?
bulb
thus the diaphragm emerges in the context of a body plan that separated an upper feeding compartment from a lower digestive tract, but the point at which it originates is a matter of definition. structures in fish, amphibians, reptiles, and birds have been called diaphragms, but it has been argued that these structures are not homologous. for instance, the alligator diaphragmaticus muscle does not insert on the esophagus and does not affect pressure of the lower esophageal sphincter. the lungs are located in the abdominal compartment of amphibians and reptiles, so that contraction of the diaphragm expels air from the lungs rather than drawing it into them. in birds and mammals, lungs are located above the diaphragm. the presence of an exceptionally well-preserved fossil of sinosauropteryx, with lungs located beneath the diaphragm as in crocodiles, has been used to argue that dinosaurs could not have sustained an active warm-blooded physiology, or that birds could not have evolved from dinosaurs. an explanation for this (put forward in 1905), is that lungs originated beneath the diaphragm, but as the demands for respiration increased in warm-blooded birds and mammals, natural selection came to favor the parallel evolution of the herniation of the lungs from the abdominal cavity in both lineages. however, birds do not have diaphragms. they do not breathe in the same way as mammals, and do not rely on creating a negative pressure in the thoracic cavity, at least not to the same extent. they rely on a rocking motion of the keel of the sternum to create local areas of reduced pressure to supply thin, membranous airsacs cranially and caudally to the fixed-volume, non-expansive lungs. a complicated system of valves and air sacs cycles air constantly over the absorption surfaces of the lungs so allowing maximal efficiency of gaseous exchange. thus, birds do not have the reciprocal tidal breathing flow of mammals. on careful dissection, around eight air sacs can be clearly seen. they extend quite far caudally into the abdomen.
thoracic diaphragm
endoscopic ultrasonography is most commonly used in the upper digestive tract and in the respiratory system. the procedure is performed by gastroenterologists or pulmonologists who have had extensive training. for the patient, the procedure feels almost identical to the endoscopic procedure without the ultrasound part, unless ultrasound-guided biopsy of deeper structures is performed.









































section::::digestive tract.









































section::::digestive tract.:upper digestive tract.
endoscopic ultrasound