Distal GI Tract Anatomy Flashcards
where does the sigmoid colon become the retum?
anterior to the S3
known as the rectosigmoid junction
where does the rectum become the anal canal?
anterior to the tip of the coccyx
just prior to passing through levator ani
where does the rectal ampulla lie?
immediately superior to the levator ani
what forms most of the pelvic diaphragm?
levator ani
what type of muscle makes up the levator ani?
skeletal muscle
what three muscles make up levator ani?
iliococcygeus
pubococcygeus
puborectalis
what does contraction of puborectalis cause?
decreases the distal angle, acting like a sphincter
what is the internal anal sphincter (IAS) made of?
smooth muscle
where is the IAS found?
superior two thirds of the anal canal
what effect does the ANS have on the IAS?
sympathetic = contraction parasympathetic = relaxation
when does the IAS relax?
always contracted
relaxes in response to distenion of the rectal ampulla
