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1

This is called achalasia. According to UpToDate, the mechanism for this diseases are generally unknown. What is known, however, is that the esophagus has a neural system called the myenteric plexus and if these ganglion cells in the esophagus are damaged in any way (e.g. physically, followed by Wallerian degeneration, or the primary process of degeneration ...


1

The structure is called the lower esophageal sphincter: Basically, its function is to prevent the contents of the stomach, including stomach acid, from "backwashing" into the esophagus. The stomach is protected from acid by a protective layer of mucus, while the esophagus is not, so any number of medical issues which cause problems with this sphincter may ...


1

I don't think this is a complete answer, but I know that historically hair, like horse tail has been used as a part of armor, because it is flexible and difficult to cut through (see dragoon helmet picture). Protection could be one of the primary purposes of facial hair in human males, who are more likely to experience aggression or be hunters.


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It is something of a misnomer to speak of CSF “circulation,” particularly in the spinal canal, as there is no continuous loop circulation of CSF as there is in the cardiovascular system. For quite some time, it has been known that CSF movement results from the formation of new CSF and motion of cilia on the surface of the choroid plexus and ependyma ...


2

CSF is actively pumped in an ebb and flow manner by the pressure with our respiratory mechanism transmitted through the pelvic diaphram onto the sacral bone that pulls on the spinal dural membranes attached at S2. Think about it: the pelvic and thoracic diaphragm are linked in a respiratory phasic contraction (confirmed with MRI). The pulling on the sacral ...


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"Position of the pelvis" is pretty vague, but there are very clear differences in pelvic morphology between females and males. This sexual dimorphism looks like: Female pelves are wider and flatter, which I think you could tell from surface anatomy. Of course if you could palpate, then you could tell for sure.


1

@KMM's comment above appears to be on the right rack. "plane" = "flat" "mixed" = "irregular" "even" & "odd" = "paired" & "unpaired" That being said: A = FALSE because jaw bones are not paired B = FALSE because sternum is not a long bone (it's a flat bone) C = FALSE because ribs are not irregular bones (they're flat bones) D = TRUE because both ...



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