Trans - Colon, Rectum, Anus Flashcards
normal frequency of defecation
3x per day to once in 3 days
odor of stool and flatus due to:
sulfur containing compounds in gut flora
gastrocolic reflex: definition
movement of the colon due to stretching of the stomach and byproducts of digestion in the small intestine
irritable bowel syndrome is caused by:
heightened visceral sensitivity causing exaggerated gastrocolic reflex
the foregut is composed of:
- GI tract from esophagus to small intestine proximal to bile duct
- liver
- pancreas
- bile ducts
the midgut is composed of:
- GI tract from small intestine distal to bile duct to proximal transverse colon
- appendix
the hindgut is composed of:
- GI tract from distal transverse colon to rectum
the large intestine is ___ in length
around 5ft
T/F: the diameter of the lumen of the colon gradually increases from the cecum to the sigmoid
F, the diameter of the colon decreases as it proceeds distally
incomplete outer longitudinal muscle layer of the colon
taenia coli
areas where the taenia coli converge
- appendix
2. rectosigmoid junction (until anus)
enumerate the 3 taenia coli and their attachments
- mesocolic - transverse and sigmoid mesocolon
- omental - appendices epiploicae
- free - no attachments
outpocketings of colon wall between taenia coli
haustrae
difference of haustrae from plicae circulares
plicae circulares encircle the whole circumference of the lumen, haustrae do not
small fatty omentum-like projectuions distributed near the area of the taenia coli along the colon wall
appendices epiploicae
functions of the colon
- absorption of water and electrolytes
2. propulsion and storage of unabsorbed fecal waste
location of cecum
right lower quadrant
T/F: the cecum is almost entirely covered by peritoneum and is suspended by a mesentery
F, it has no mesentery
entrance of the ileum into the cecum
ileocecal valve
T/F: the ileocecal valve is a true sphincter
F
importance of appendix in embryo
part of the immune system (GALT)
appendix is most commonly located
retrocecally
the mesentery of the appendix is the:
mesoappendix
McBurney’s point
historically a common basis for locating the appendix on a diagonal incision
1/3 of the way along the oblique line joining the ASIS and the umbilicus
since the position of the appendix is variable, surgeons now prefer to make an incision on the:
point of maximal tenderness
T/F: the ascending colon is intraperitoneal
F, it is retroperitoneal
T/F: the ascending colon has no mesentery
T
innervation of ascending colon
vagus
longest part of the colon
transverse colon
T/F: the transverse colon is intraperitoneal
T
T/F: the transverse colon has no mesentery
F
mesentery of the transverse colon
mesocolon
T/F: the descending colon is retroperitoneal
T
T/F: the sigmoid colon is retroperitoneal
F
part of the colon most prone to volvulus
sigmoid colon due to triangular mesentery
site at which the sigmoid colon becomes the rectum
rectosigmoid junction
branches of the superior mesenteric artery
- middle colic artery
- right colic artery
- ileocolic artery
blood supply of transverse colon
middle colic artery
blood supply of ascending colon
right colic artery
ileocolic artery
anastomosis of arteries of ascending and descending colon
marginal artery of Drummond
T/F: the inferior mesenteric artery and the superior mesenteric artery can be cut and the bowels still survive
T, but the small intestine will die as a result of cutting the superior mesenteric artery
anastomosis between middle and left colic artery
arc of Riolan / meandering mesenteric artery
area of poor blood supply in the region of the splenic flexure
point of Griffith
blood supply of descending colon
left colic arteries
blood supply of sigmoid colon
sigmoid arteries
lymph drainage of colon and proximal rectum
paraaortic lymph nodes
lymph drainage of colon and distal rectum
internal iliac and superficial inguinal nerves
sympathetic innervation of colon
lower thoracic and upper lumbar segments of spinal cord
superior mesenteric plexus, inferior mesenteric plexus, hypogastric plexus
parasympathetic innervation of colon
- vagus nerves - ascending colon up to splenic flexure
2. sacral nerves - descending colon and sigmoid colon
plexus that controls colonic motility
Auerbach’s plexus, submucous plexus, Meissner’s plexus
the rectum ends at the
anorectal ring
extraperitoneal rectum covered by:
fascia propria
flexures of the rectum
- sacral flexure
- anorectal flexure
- lateral flexures
mucosal infoldings of the rectum
valves of Houston / transverse rectal folds
space where fecal matter is stored until defacation
ampulla of rectum
fossa that provides space for the rectum to distend
pararectal fossae
fascia that divides the retrorectal space into superior and inferior portions
Waldeyer’s fascia
fascia that separates prostate and bladder from anterior rectum in males, and is associated with the vagina in females
Denonvillier’s fascia
fascia that prevents lateral movement of rectum
lateral stalks
divisions of rectum
- upper - from sacral promontory to anterior peritoneal reflection
- middle - from anterior peritoneal reflection to 5-6cm above anal verge
- lower - from top of anal sphincter to anal verge
autonomic anal sphincter
internal anal sphincter
three loops of external anal sphincter
- puborectalis
- superficial anal sphincter
- subcutaneous portion
parasympathetic stimulation causes the internal anal sphincter to:
relax
sympathetic stimulation causes the internal anal sphincter to:
contract
longitudinal columns within anal canal
columns of Morgagni
line connecting the bases of the columns of Morgagni
dentate line
landmark for the intermuscular border between internal and external anal sphincters
Hilton’s white line
line that indicates the junction of the superior and inferior parts of the anal canal (superior part is from hindgut, inferior is from proctodeum)
dentate/pectinate lie
posteriorly and laterally thickened upper portion of the anal canal, pulled by the puborectalis
anorectal ring
anorectal angle when
a. normal
b. sitting
c. squeezing the sphincter
a. 102
b. 119
c. 81
arterial supply of rectum and anus
- superior rectal artery - from inferior mesenteric
- middle rectal artery - from internal iliac
- inferior rectal artery - from internal pudendal
veins that form internal hemorrhoidal plexus
- superior rectal vein
2. middle rectal vein
veins that form external hemorrhoidal plexus
inferior rectal vein
difference between internal and external hemorrhoidal plexuses
internal - above dentate line
external - below dentate line
sympathetic innervation of rectum and anus
L1 to L3
parasympathetic innervation of rectum and anus
- S2 to S4
2. nervi erigentes - S3-S4
condition where outpouchings in the colon occur
diverticulosis
condition where a part of the colon has failed to correctly form, and that part is eight blocked or is altogether missing
colonic atresia
twisting of the colon on itself or on the stalk of mesenteric tissue
volvulus
condition where one section of the bowel tunnels into another section
intussusception
acute inflammation of the appendix
appendicitis
enlargement of rectal venous plexus secondary to portal hypertension blockage/increase in portal vein pressure
hemorrhoids
T/F: external hemorrhoids are painless while internal hemorrhoids are painful
F, it is the other way around
the nerve/s involved in internal hemorrhoids
inferior hypogastric plexus
the nerve/s involved in external hemorrhoids
rectal nerve
the vein inflamed in internal hemorrhoids
superior rectal vein
the vein inflamed in external hemorrhoids
inferior rectal vein
grading of hemorrhoids
Grade 1 - hardly seen
Grade 2 - bulges then disappears
Grade 3 - visible bulges can be pushed inside
Grade 4 - cannot be pushed inside
cancer in the proximal colon often causes:
diarrheal symptoms
cancer in the distal colon often causes:
constipation, obstruction
anal warts
condylomas
condition wherein the walls of the rectum protrude through the anus
rectal prolapse
absence of normal anal opening
imperforate anus
surgical removal of appendix
appendectomy
apple core deformity in barium enema indicates:
tumor
process by which a badly damaged esophagus is surgically replaced with the transverse colon
colonic interposition