Examples of anal canal in the following topics:
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- Ischioanal fossa – a fat-filled space at the lateral sides of the anal canal.
- It is bounded laterally by obturator internus muscle, medially by pelvic diaphragm and the anal canal.
- Pudendal canal – contains internal pudendal artery and the pudendal nerve.
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- A sufficient increase in fecal material in the rectum causes stretch receptors from the nervous system, located in the rectal walls, to trigger the contraction of rectal muscles, relaxation of the internal anal sphincter, and an initial contraction of the skeletal muscle of the external sphincter .
- The relaxation of the internal anal sphincter causes a signal to be sent to the brain indicating an urge to defecate.
- The perineal wall is lowered, causing the anorectal angle to decrease from 90 degrees to less than 15 degrees (almost straight), and the external anal sphincter relaxes.
- The rectum now contracts and shortens in peristaltic waves, thus forcing fecal material out of the rectum and out through the anal canal.
- The internal and external anal sphincters, along with the puborectalis muscle, allow the feces to be passed by pulling the anus up and over the exiting feces in shortening and contracting actions.
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- The hindgut is the last third of the transverse colon, descending colon, rectum, and upper part of the anal canal.
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- The large intestine consists of the cecum, colon, rectum, and anal canal.
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- Animals in the phylum Chordata share four key features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
- The post-anal tail is a posterior elongation of the body, extending beyond the anus.
- In humans and other apes, the post-anal tail is present during embryonic development, but is vestigial as an adult.
- In chordates, four common features appear at some point during development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
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- The gizzard leads to the intestine and ends in an anal opening.
- Annelids possess a closed circulatory system of dorsal and ventral blood vessels that run parallel to the alimentary canal as well as capillaries that service individual tissues.
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- This central region surrounds the central canal,
which is an anatomic extension of the spaces in the brain known as the
ventricles and like the ventricles, contains cerebrospinal fluid.
- The nerves that compose the cauda equina supply the pelvic organs and
lower limbs, including motor innervation for the hips, knees, ankles, feet, and internal and external anal sphincters.
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- Members of these groups also possess the four distinctive features of chordates at some point during their development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
- Adults only maintain pharyngeal slits and lack a notochord, a dorsal hollow nerve cord, and a post-anal tail.
- Members of Cephalochordata possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail in the adult stage.
- (b) The larval stage of the tunicate possesses all of the features characteristic of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
- Adult lancelets retain the four key features of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
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- In 1808, a government-sponsored Report on the Subject of Public Roads and Canals suggested that the federal government should fund the construction of interstate turnpikes and canals.
- Among the most important of these canals was the Erie Canal.
- The success of the Erie Canal led to a proliferation of smaller canal routes in the region.
- Most of the canal work was done by Irish immigrants who had previously worked on the Erie Canal.
- The Illinois and Michigan Canal was an important canal in the nineteenth century, but was rendered obsolete when new railroads replaced it.