The Anal Canal Flashcards
what proportion of the anal canal is surrounded by the internal anal sphincter
upper two thirds
what formed the internal anal sphincter
a thickening of the involuntary circular smooth muscle in the bowel wall
which type of muscle is the external anal sphincter
voluntary
what proportion of the anal canal is surrounded by the external anal sphincter
lower two thirds
which portion of the anal canal has overlap of the two sphincters
the middle third
what forms the anorectal ring
fusion of the internal anal sphincter and external sphincter
describe how anal valves are formed
mucosa of the anal canal is arranged into longitudinal folds joined at the inferior ends by anal valves which collectively form an irregular circle known as pectinate line which divides the anal canal into its upper and lower parts
describe the arterial supply of the anal canal above the pectinate line
superior rectal artery
what is the superior rectal artery a branch of
the superior mesenteric artery
describe the arterial supply of the anal canal below the pectinate line
inferior rectal artery
what is the internal rectal artery a branch of
the internal pudendal artery
describe the venous drainage of the anal canal above the pectinate line
superior rectal vein
what does the superior rectal vein empty into
the inferior mesenteric vein
describe the venous drainage of the anal canal below the pectinate line
inferior rectal vein
what does the inferior rectal vein empty into
the internal pudental vein
