Hemorroids overview
In the upper anal canal, the hemorrhoids cushions are composed of three submucosal pillars of sinusoids within connective tissue, generally in the left lateral, right anterior, and right posterior. During the act of defecation, the hemorrhoids cushions become engorged with blood, cushioning the anal canal and supporting the anal canal lining. The pathologic term hemorrhoids is used to describe the downward displacement of the cushion along with dilation of the contained sinusoids and sometimes bleeding from the arteriole, venule, or sinusoidal portion.Hence, hemorrhoids develop when the supporting tissues of the anal cushion deteriorate or with extensive downward pressure, as in prolonged straining at stool or pregnancy.