Sigmoidal
Sigmoidal or sigmoid, literally means S-shaped and can refer to: * Sigmoid function * Sigmoidal artery * Sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...

Sigmoid Function
A sigmoid function is a mathematical function having a characteristic "S"-shaped curve or sigmoid curve. A common example of a sigmoid function is the logistic function shown in the first figure and defined by the formula: :S(x) = \frac = \frac=1-S(-x). Other standard sigmoid functions are given in the Examples section. In some fields, most notably in the context of artificial neural networks, the term "sigmoid function" is used as an alias for the logistic function. Special cases of the sigmoid function include the Gompertz curve (used in modeling systems that saturate at large values of x) and the ogee curve (used in the spillway of some dams). Sigmoid functions have domain of all real numbers, with return (response) value commonly monotonically increasing but could be decreasing. Sigmoid functions most often show a return value (y axis) in the range 0 to 1. Another commonly used range is from −1 to 1. A wide variety of sigmoid functions including the logistic and ...
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Sigmoidal Artery
The sigmoid arteries are 2-5 branches of the inferior mesenteric artery that are distributed to the distal descending colon and the sigmoid colon. Anatomy Course and relations The sigmoid arteries course obliquely inferior-ward and to the left, passing posterior to the peritoneum and in anterior to the psoas major, ureter, and gonadal vessels. Anastomoses The sigmoid arteries anastomose with the left colic superiorly, and with the superior rectal artery The superior rectal artery (superior hemorrhoidal artery) is an artery that descends into the pelvis to supply blood to the rectum. Structure The superior rectal artery is the continuation of the inferior mesenteric artery. It descends into the ... inferiorly. References External links * - "Intestines and Pancreas: Branches of the Inferior Mesenteric Artery" * Arteries of the abdomen {{circulatory-stub ...
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