Anatomy - Abdominal Organs: Hollow Viscera Flashcards
4 major regions of the stomach
Cardia
Fundus
Body
Pylorus
2 curvatures of the stomach
Greater curvature
Lesser curvature
The lower esophageal sphincter (LES) has 2 parts…
- External sphincter (i.e. right crus of the diaphragm)
- Internal sphincter
Describe the external sphincter of the LES.
How is it influenced by respiration?
The right crus of the diaphragm loops around the esophagus to form a sling.
Upon inspiration, the intra-abdominal pressure increases. Therefore, the sling (external sphincter) constricts the esophagus and prevents stomach contents & acid from refluxing into the esophagus.
Describe the internal sphincter of the stomach.
* Type of muscle
* Voluntary or involuntary
It is a bundle of smooth muscle within the wall of the esophagus. It is not under voluntary control.
What is a hiatal hernia?
When part of the stomach herniates up into the thoracic cavity (above the diaphragm).
What are the 2 types of hiatal hernias?
- Sliding hiatal hernia
- Rolling (paraesophageal) hiatal hernia
Which type of hiatal hernia is the most common?
Sliding hiatal hernias (95%)
What is a sliding hiatal hernia?
When the gastroesophageal junction moves above the diaphragm together with some of the stomach.
What is a rolling (aka paraesophageal) hiatal hernia?
When part of the stomach herniates through the esophageal hiatus of the diaphragm, and lies beside the esophagus, but without movement of the gastroesophageal junction.
Name the muscular valve of smooth muscle at the bottom of the stomach that controls the flow of food into the small intestine
Pyloric sphincter
What is pyloric stenosis? What is the main symptom? When does it usually occur?
- Spasmodic contraction of the pyloric sphincter can cause the muscle to hypertrophy, causing stenosis. This restricts the ability of stomach contents to pass through.
- It causes severe non-bilious projectile vomiting.
- Usually occurs in the first few months of life (2-12 weeks).
What are the names of the 4 regions of the duodenum?
1: Superior
2: Descending
3: Inferior
4: Ascending
Describe the first part of the duodenum. (4)
- It is a continuation of the pylorus.
- It is intraperitoneal
- It is connected to the liver via the HD lig.
- It ends at the superior duodenal flexure
Describe the second part of the duodenum. (4)
- Begins at the superior duodenal flexure
- It is retroperitoneal
- Features the major (& minor) duodenal papilla
- Ends at the inferior duodenal flexure
What are the major & minor papilla?
Major: Opening in the duodenum where the common bile duct and pancreatic duct empty into the digestive tract
Minor: Opening in the duodenum for the accessory pancreatic duct
Describe the third part of the duodenum. (4)
- Begins at the inferior duodenal flexure
- It is retroperitoneal
- Crosses anterior to the aorta and IVC
- Crosses posterior to the superior mesenteric artery (SMA)
Describe the fourth part of the duodenum. (3)
- Ascends up the inferior border of the pancreas
- It is intraperitoneal
- Ends at the duodenojejunal flexure
The second and third parts of the duodenum are retroperitoneal. What does this mean?
It means these regions are anchored to the body wall and cannot be mobilized.
Which part of the duodenum is connected to the portal triad?
The first part of the duodenum (the portal triad passes through the hepatoduodenal ligament of the lesser omentum).
The first part (superior) of the duodenum is a continuation of…
the pylorus
The first (superior) part of the duodenum is connected to…
the liver via the hepatoduodenal ligament
Characteristic feature of the second (descending) part of the duodenum
Major (& minor) papilla
Which parts of the duodenum are intraperitoneal?
Which parts of the duodenum are retroperitoneal?
Intraperitoneal: 1 and 4
Retroperitoneal: 2 and 3
What is the name of the muscle that suspends the 4th part of the duodenum (connects it to the diaphragm)?
Ligament of Treitz
What is the ligament of Treitz? Where are its muscle fibres derived from?
- A muscle/ligament that suspends the 4th part of the duodenum, connecting it to the diaphragm
- Its muscle fibres are derived from the right crus of the diaphragm
The ligament of Treitz marks the location of…
the duodenojejunal junction
3 regions of the small intestine
- Duodenum
- Jejunum
- Ileum
How can we differentiate the jejunum and ileum
Jejunum:
* longer vasa recta (blood vessels)
* fewer arcades
* Plicae circulares (circular folds, increase absorptive surface)
Ileum:
* shorter vasa recta
* more arcades
* Peyer’s patches
* More fat in the mesentery
What is the most common congenital abnormality of the small intestine?
Meckel’s diverticulum
What is Meckel’s diverticulum
- A congenital abnormality of the SI.
- Results from incomplete obliteration of the vitelline duct.
- Located in the distal ileum.
- Forms a small pouch or blind segment that could get infected.
What is intussusception?
When part of the intestine invaginates into an adjacent section of intestine. Can obstruct passage of contents and block blood supply (risk of necrosis).
Junction between small and large intestine
Ileocecal junction
The greater curvature of the stomach is supplied by…
the right gastroepiploic artery (extension of the gastroduodenal a.) and the lest gastroepiploic artery (branch of the splenic a.)
What is the cecum?
A blind pouch that forms the first part of the large intestine
What is the ileocecal orifice/valve?
Muscular valve that controls flow of food from the SI to the LI.
What is the appendix?
Extension of the cecum
What is McBurney’s point?
It is the most common location of the base of the appendix (1/3 distance from ASIS to umbilicus).
Tenderness at McBurney’s point suggests… (2)
a) Specific localization of tenderness signifies the inflammation is no longer limited to the lumen of the bowel (visceral pain is diffuse). The inflammation is now irritating the parietal peritoneum (somatic pain has specific localization).
b) Suggests evolution of acute appendicitis to a later stage, with increased likelihood of rupture.
What quadrant does appendicitis usually present in…
the lower right quadrant
Why could appendicitis occur in the lower left quadrant?
situs inversus
Name the regions of the colon
Cecum
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Name the 2 flexures of the colon and what parts of the colon they separate?
Hepatic flexure: between the ascending and transverse colon
Splenic flexure: between the transverse and descending colon
What are epiploic appendices
Little lobules of fat that hang off the large intestine (esp. sigmoid colon)
What are taenia coli?
Three separate longitudinal ribbons of smooth muscle on the outside of the colon.
How do taenia coli contract?
The contract length-wise to shorten the colon (promote peristalsis)
What are haustra?
Small pouches caused by tension of the taenia coli (give the colon its segmented appearance)
Diverticulosis
A condition where abnormal outpocketings (diverticula) form in the colon through weaknesses in the muscle layers of the colon wall.
Diverticulosis develops when these diverticula become inflamed.
Which part of the colon is usually affected by diverticulosis?
Sigmoid colon (because it is often under increased pressure).
What is volvulus?
A condition where a loop of bowel twists around its site of mesenteric attachment.
What are the 2 mechanisms by which volvulus produces symptoms? What are those symptoms?
- Bowel obstruction, which results in abdominal distension, vomiting and lack of defecation
- Ischemia to the affected portion of the intestine (necrosis)
The sigmoid colon is…
a) intraperitoneal
b) retroperitoneal
a) intraperitoneal
The rectum is…
a) intraperitoneal
b) retroperitoneal
b) retroperitoneal
Name the 2 anal sphincters
Internal anal sphincter
External anal sphincter
Pelvic floor muscle that contributes to continence (rectum)
Levator ani
GI blood supply is divided embryologically (foregut, midgut, hindgut). Explain.
Foregut: Celiac trunk
Midgut: Superior mesenteric artery
Hindgut: Inferior mesenteric artery
What are the organs of the foregut (celiac trunk)?
- Esophagus (lower part)
- Stomach
- Duodenum
- Pancreas, liver gallbladder
- Spleen
What are the organs of the midgut (superior mesenteric artery)?
- Small intestine
- Cecum
- Appendix
- Ascending colon
- Proximal 2/3 of transverse colon
What are the organs of the hindgut (inferior mesenteric artery)?
- Distal 1/3 of transverse colon
- Descending colon
- Sigmoid colon
- Rectum
3 main branches of the celiac trunk and what they supply
- Common hepatic artery (stomach, liver, duodenum, pancreas)
- Left gastric artery (stomach)
- Splenic artery (spleen)
The common hepatic artery splits into… (2)
- proper hepatic (supplies liver)
- gastroduodenal (supplies stomach and duodenum)
The lesser curvature of the stomach is supplied by…
The right gastric artery (branch of the hepatic a.) and the left gastric artery (branch of the celiac trunk)
The greater curvature of the stomach is supplied by…
the right gastroepiploic artery (extension of the gastroduodenal a.) and the lest gastroepiploic artery (branch of the splenic a.)
The fundus of the stomach is supplied by…
short gastric arteries (branches of the splenic artery)
The lower portion of the esophagus is supplied by…
ascending esophageal arteries (branches of the left gastric artery)
Arteries supplying the duodenum
Superior pancreaticoduodenal arteries (ant. & post.)
Inferior pancreaticoduodenal arteries (ant. & post.)
for a total of 4 arteries
Superior pancreaticoduodenal arteries originate from…
the gastroduodenal artery (celiac trunk)
Inferior pancreaticoduodenal arteries originate from…
the superior mesenteric artery (SMA)
Describe the blood supply to…
a) jejunum
b) ileum
c) cecum
d) ascending colon
e) proximal 2/3 of transverse colon
a) Jejunum is supplied by jejunal arteries (from SMA)
b) Ileum is supplied by ileal arteries (from SMA)
c) Cecum is supplied by ileocolic artery (from SMA)
d) Ascending colon is supplied by right colic artery (from SMA)
e) Transverse colon (2/3) is supplied by left and right branches of the middle colic artery (from SMA)
The left colic artery is a branch of … and supplies…
The left colic artery is a branch of the inferior mesenteric artery (IMA) and supplies the distal 1/3 transverse colon and descending colon
Sigmoid colon is supplied by…
sigmoidal arteries (from IMA)
Blood supply to the rectum is provided by…
the superior rectal artery (branch of the IMA)
What is the Marginal artery?
An anastomotic channel formed by the following arteries:
* right colic a.
* middle colic a.
* left colic a.
* sigmoidal arteries
All the blood from the GI drains to what organ?
Liver (for detoxification, filtration)
What vein drains blood of the GI tract to the liver?
Hepatic portal vein
Veinous drainage of the midgut
Veinous drainage of the hindgut
Midgut is drained by superior mesenteric vein.
Hindgut is drained by inferior mesenteric vein.
3 veins that fuse to form the hepatic portal vein going to the liver
Superior mesenteric vein
Inferior mesenteric vein
Splenic vein
