GI Organs (Pt. 2) Flashcards
What is the beginning point and the end point of the ascending colon?
beginning point = cecum
end point = right colic flexure
What is lateral to the ascending colon?
right paracolic gutter
Is the ascending colon retroperitoneal or intraperitoneal?
-retroperitoneal
What is the blood supply to the ascending colon?
- ileocolic A.
- right colic A.
-both from SMA
What is the venous drainage for the ascending colon?
- ileocolic V.
- right colic V.
What lymph nodes drain the ascending colon?
-epicolic and paracolic LN’s
What is the nerve supply for the ascending colon?
superior mesenteric nerve plexus
- T1-T10
- vagus N.
What part of the colon is the longest and most flexible?
transverse colon
What are the starting and ending points of the transverse colon?
starting point: right colic flexure
ending point: left colic flexure
Which colic flexure is more superior and why?
left colic flexure d/t attachment to the diaphragm by the phrenicocolic ligament
Is the transverse colon retroperitoneal or intraperitoneal?
intraperitoneal
-attached by the transverse mesocolon
What is the blood supply to the transverse colon?
middle colic A.
What is the venous drainage from the transverse colon?
superior mesenteric V.
What is the lymph drainage for the transverse colon?
middle colic LN’s
What is the nerve supply for the transverse colon?
superior mesenteric plexus
- T10-L2
- vagus N.
What is the beginning point and end point of the descending colon?
beginning = left colic flexure end = sigmoid colon
What is lateral to the descending colon?
left paracolic gutter
Is the descending colon retroperitoneal or intraperitoneal?
retroperitoneal
What is the blood supply to the descending colon?
left colic A.
sigmoid A.
-both from inferior mesenteric A.
What is the venous drainage from the descending colon?
inferior mesenteric V.
What is the lymph drainage from the descending colon?
epicolic and paracolic LN’s
What is the nerve supply to the descending colon?
sympathetic: T12-L2
parasympathetic: pelvic splanchnic nn. via inferior hypogastric nerve plexus
What is the beginning and the end of the sigmoid colon?
beginning: descending colon
end: rectum
Is the sigmoid colon retroperitoneal or intraperitoneal?
intraperitoneal
- attached by sigmoid mesocolon
- -allows freedom of mvmt in the middle
What is a characteristic about the omental appendices of the sigmoid colon?
long omental appendices
What is the blood supply to the sigmoid colon?
- left colic A.
- sigmoid A.
- from the inferior mesenteric A.
What is the venous drainage of the sigmoid colon?
inferior mesenteric V.
What is the lymph drainage from the sigmoid colon?
epicolic and paracolic LN’s
What is the nerve supply to the sigmoid colon?
sympathetic: T12-L2
parasympathetic: pelvic splanchnic nn. via inferior hypogastric nerve plexus
What are the longitudinal bands along the colon and of what do they consist?
teniae libera, epiploic teniae, and mesocolic teniae
- omental appendices attach to epiploic teniae
- mesoclons attach to the mesocolic teniae
-longitudinal bands of smooth muscle
What is the role of the colon?
water reabsorption
What is formed by the ctx of the teniae coli?
haustra = sacculations of the wall of the colon
What is the anatomical position of the appendix?
- attached to the posteromedial part of the cecum
- supported by mesoappendix
- inferior to ileocecal junction
What are symptoms of appendicitis?
- low-grade fever and ill-looking appearance
- increased pain w/ cough (Dunphy)
- tenderness at McBurney’s Point
- involuntary guarding
- pain in RLQ when LLQ is palpated (Rovsing)
What are characteristics of anatomical lobes of the liver?
- not true lobes per biological definition
- only exist as R and L d/t liver’s internal architecture
- R lobe is larger and contains accessory lobes
- -(caudate and quadrate lobes)
- R and L separated by falciform L. and L sagittal fissure
What are characteristics of functional lobes of the liver?
- functionally independent of one another
- each lobe has its own branch of hepatic A. and V.
- each lobe is drained by its own hepatic duct
- R lobe is somewhat larger, though size is equalish
What is unique about the caudate lobe that makes it like a “third liver”?
-receives vascularization from both branches of the bifurcation of the portal triad
Clinical Box: Esophageal Varices
- caused by portal HTN
- -blood can’t pass thru liver, so reverses into esophagus
- severe, life-threatening hemorrhage
- common in pts w/ alcoholic cirrhosis of the liver
Clinical Box: Pyrosis
- most common type of esophageal discomfort
- burning sensation in abdominal part of esophagus
- result of regurgitation of food and/or fluid
- may be associated w/ hiatal hernia
- perceived as a chest sensation vs. abdominal
Clinical Box: Bariatric Sx
- performed on morbidly obese
- most frequent performed stomach sx (laparoscopic)
-aim to reduce stomach volume, reduce nutrient absorptive area, or a combo
What are examples of restrictive bariatric surgeries?
- banding
- resectioning to create a pouch or sleeve
- folding stomach onto itself
What are examples of malabsorptive bariatric surgeries?
-rerouting the connection of the stomach with the small intestines
What is an example of a mixed procedure bariatric surgery?
-gastric bypass
What are the results of bariatric surgery?
- significant weight loss
- reduced diabetes
- reduced malabsorptive syndrome
- reduced sleep apnea
True or False: bariatric surgeries have a relatively high risk of post-surgical complications
True; strict adherence to a post-surgical diet of healthy eating is required for success
Clinical Box: Displacement of Stomach
- pancreatic pseudocysts and abscesses in omental bursa may push stomach anterior
- visible in diagnostic imaging
What is a complication of pancreatitis that involves the stomach?
-following pancreatitis, the posterior wall of the stomach may adhere to part of the posterior wall of the omental bursa that covers the pancreas
Clinical Box: Pylorospasm
- sometimes occurs in infants 2-12wks
- failure of smooth muscle fibers around pylorus to relax
- food doesn’t pass to duodenum easily
- stomach becomes overly full
- discomfort and vomiting
Clinical Box: Congenital Hypertrophic Pyloric Stenosis
- thickening of smooth muscle in pylorus
- more common in males; possible genetic factors
- elongated, overgrown pylorus, narrow canal
- dilated stomach proximal to pylorus
- Tx: pylorotomy, cut through hypertrophied circular M.
Clinical Box: Carcinoma of the Stomach
- malignant tumor in body or pylorus, may be palpable
- gastroscope inspects mucosa of inflated stomach
- stomach has extensive lymph drainage
- -impossible to remove all LN’s (ex: aortic and celiac)
- most gastric CA detected too late for Sx control
Clinical Box: Gastrectomy and LN Resection
- total gastrectomy is uncommon
- arteries may be ligated during a partial gastrectomy
- -circulation unaffected d/t many anastomoses
- all gastric LN’s drain to celiac LN’s
Clinical Box: Visceral Referred Pain
- organic pain varies from dull to severe
- -poorly localized and radiates to dermatome level
-visceral referred pain in skin region supplied by same sensory ganglia and spinal cord segment
Clinical Box: Duodenal Ulcers
- most occur on posterior wall of superior part
- occasionally an anterior ulcer perforates the wall and contents enter the peritoneum, causing peritonitis
What are some complications of duodenal ulcers?
-liver, GB and pancreas in close proximity to superior part may adhere or become ulcerated themselves
- intraluminal bleeding
- erosion of gastroduodenal A. and severe hemorrhage
Clinical Box: Development Changes in Mesoduodenum
- in early fetal period, entire duodenum has mesentery
- -most fuses to posterior wall b/c of pressure from overlying transverse colon
What is the surgical significance of the duodenum being secondarily retroperitoneal?
-duodenum (and pancreas) can be separated from underlying retroperitoneal viscera during surgery involving the duodenum w/o damaging blood supply to the kidneys and ureters
What are the duodenal fossae?
- 2-3 inconsistent folds around the duodenojejunal flexure: superior, para, and inferior duodenal fossae
- paraduodenal fossa is large, to the left of ascending duodenum
Why is the paraduodenal fossa of clinical significance?
- it is large
- if a loop of intestine enters, it can become strangulated
-during Sx, be careful not to injure branches of IMA/IMV or branches of the left colic A.
Clinical Box: Embryological Rotation of Midgut
- for a 4wk period, midgut (supplied by SMA) is herniated into proximal part of umbilical cord
- as it is allowed to recede d/t decrease in relative size of kidneys and liver, it rotates 270 around SMA axis
Clinical Box: Navigating the Small Intestines
-place hand, finger, and thumb on each side of intestine and grasp mesentery
- follow mesentery to its root, untwisting as needed
- cranial = orad and caudal = aborad
Clinical Box: Ischemia of the Intestines
- occlusion of vasa recta
- if severe, necrosis results and leads to paralytic obstruction of the intestine (aka: ileus)
What are the symptoms of ischemia of the intestines?
- severe colicky pain
- abdominal distention
- vomiting
- fever
- dehydration
What is the mechanism for the occlusion of the vasa recta that causes intestinal ischemia?
- emboli from the heart sent inferiorly via descending aorta tend to lodge in the SMA and its branches
- b/c SMA arises at a less acute angle from the aorta than other branches such as the celiac trunk
Clinical Box: Appendectomy
- standard procedure is laparscopic
- peritoneal cavity inflated with carbon dioxide
-if surgeons have trouble finding appendix, they look for convergence of the teniae coli on surface of cecum
Clinical Box: Mobile Ascending Colon
- in 11 percent of people, the cecum and proximal colon are mobile d/t a mesentery
- may cause cecal bascule (folding) or volvulus and intestinal obstruction
What is the treatment for Mobile Ascending Colon?
-cecopexy = fixation … teniae coli of the cecum is sutured to the abdominal wall
Clinical Box: Colonoscopy, Sigmoidoscopy and Colorectal Cancer
-small instruments can be passed through scopes to facilitate minor procedures (biopsies, etc.)
- most tumors occur in sigmoid (men and younger pts)
- ascending colon tumors more common in women
Clinical Box: Diverticulosis
- multiple false diverticula develop on intestine
- primarily affects mid-age and elderly; sigmoid colon
- occur commonly where nutrient aa. perforate bowel
- diverticula subject to infection and rupture
- -diverticulitis can distort or erode nutrient aa.
What type of diet is beneficial in reducing occurrence of diverticulosis?
high fiber diet
Clinical Box: Volvulus of the Sigmoid Colon
-twisting of the sigmoid colon d/t long middle portion of the sigmoid mesocolon
- results in obstruction and ischemia
- acute emergency; necrosis if untreated
