Anus, Rectum & Prostate Flashcards
What forms the terminal portions of the GI tract?
rectum and anus
How long is the anal canal?
2.5 to 4 cm and opens onto the perineum
What is the characteristic of the tissue visible at the external margin of the anus?
moist and hairless mucosa
What is the characteristic of the juncture with the perianal skin?
increased pigmentation and in the adult, presence of hair
What normally keeps the anal canal closed?
concentric rings of muscle- the internal and external sphincters
Which concentric ring is under involuntary autonomic control?
the internal ring
What causes the URGE to defecate?
when the rectum fills with feces and causes reflective stimulation that relaxes the internal sphincter
What controls defecation?
controlled by the striated external sphincter which is under voluntary control
What supplies the lower half of the canal making it sensitive to painful stimuli?
somatic sensory nerves
What supplies the upper half of the canal, making it relatively insensitive to pain?
autonomic control
What lines the anal canal that fuse to form the anorectal junction?
lined by columns of mucosal tissue (columns of Morgagni) that fuse to form the anorectal junction
What are the spaces between the columns of Margagni called that anal glands empty into?
crypts
What can be the result of inflammation of the crypts?
fistula or fissure formation
What is it called when anastomosing veins cross the columns forming a ring?
zona hemorrhoidalis
Dilation of the zonal hemorrhoidalis veins causes what?
internal hemorrhoids
The lower segment of the anal canal contains a venous plexus that drains into the ___ ____ ____.
inferior rectal veins
Dilation of the inferior rectal veins results in what?
external hemorrhoids
How long is the rectum?
12 cm long
The proximal end of the rectum is continuous with the ______.
sigmoid colon
Is the distal end of the rectum at the anorectal junction, is the sawtooth- like edge palpable?
NO just visual on proctoscopic exam
Above the anorectal junction, the rectum ____ and turns ___ into the hallow of the coccyx and sacrum, forming the ____ ____.
dilates, posteriorly, rectal ampulla
What is stored in the rectal ampulla?
flats and feces
What are the 3 semilunar traverse folds of the rectal wall?
Houston valves
The prostate is ____ and divided by a shallow median sulcus into ______.
convex; right and left lateral lobes