Anatomy Lecture 3 -- Abdomen 3 Flashcards
Identify the 4 divisions of the stomach
- Cardia
- Fundus
- Body
- Pylorus
2 sphincters associated with the stomach
- Lower esophageal sphincter
- Pyloric sphincter (valve)
2 sphincters at the lower end of the esophagus
- External sphincter (right crus of the diaphragm)
- Internal sphincter (LES)
Anatomically define the external sphincter (right crus of the diaphragm)
Loop of muscle around the esophagus likea sling
Function of the external sphincter (right crus of the diaphragm)
Upon inspiration, constricts the esophagus to prevent the stomach contents from refluxing up the esophagus when intra-abdominal pressure rises during inspiration
Anatomically define the internal sphincter (LES)
A bundle of muscle at the low end of the esophagus, where it meets the stomach
Function of the internal sphincter (LES)
Closed = prevent acid and stomach contents from traveling backwards from the stomach. Not under voluntary control
Define a hiatus hernia (in general)
The protrusion (or herniation) of the upper part of the stomach into the thorax through a tear or weakness in the diaphragm
2 major kinds of hiatus hernias
- Sliding hiatus hernia (most common - 95%)
- Rolling (or paraesophageal) hiatus hernia
Define a sliding hiatus hernia
Gastroesophageal junction moves above the diaphragm together with some of the stomach
Define a rolling (or paraesophageal) hiatus hernia
A part of the stomach herniates through the esophageal hiatus and lies beside the esophagus, without movement of the gastroesophageal junction.
Consequence of a spasmodic contraction of the pyloric sphincter
Prevention of food from passing easily into the duodenum, causing discomfort and vomiting
May occur in 2 - 12 week old infants
Define pyloric stenosis
Narrowing of the opening from the stomach to the first part of the duodenum, due to enlargement (hypertrophy) of the muscle surrounding this opening which spasms when the stomach empties
When does pyloric stenosis most often occur?
In the first few months of life
Consequence of pyloric stenosis
Severe projectile non-bilious vomiting
Identify the 4 parts of the duodenum and their respective lengths
- Superior = ~5 cm
- Descending = ~7 - 10 cm
- Inferior/horizontal = ~ 5 - 7.5 cm
- Ascending = ~5 cm
Describe the anatomy of the first part (superior) of the duodenum (5)
- Begins as a continuation of the duodenal end of the pylorus
- Passes laterally (right) superiorly and posteriorly on the right side of L1, before making a sharp curve inferiorly
- Lies on the transpyloric plane
- Ends at the superior duodenal flexure
- First half is intraperitoneal, connected to liver via the hepatoduodenal ligament
Describe the anatomy of the second part of the duodenum (descending) (4)
- Begins at the superior duodenal flexure
- Passes inferiorly to the lower border of vertebral body 3, before making a sharp turn medially
- Pancreatic duct and bile duct open into it (ampulla of Vater)
- Ends at the inferior duodenal flexure
Describe the anatomy of the third part (inferior/horizontal) of the duodenum (2)
- Begins at the inferior duodenal flexure
- Passes transversely to the left, crossing the right ureter, right testicular/ovarian vessels, IVC, aorta, superior mesenteric artery and vertebral column
Describe the anatomy of the fourth part (ascending) of the duodenum (2)
- Passes superiorly, ascends on the left side of the aorta, up to the level of the upper border of L2 and the inferior border of the body of the pancreas
- Curves anteriorly and terminates at the duodenujejunal flexure (ligament of Treitz)
Important anatomical landmark of the duodenojejunal junction
Ligament of Treitz
Function of the ligament of Treitz
Suspensory muscle that connects the fourth part of the duodenum to the diaphragm
Anterior relations of the first part of the duodenum
- Quadrate lobe of liver
- Gall bladder
Posterior relations of the first part of the duodenum
- Lesser sac (first ~2.5 cm)
- Gastroduodenal artery
- Bile duct
- Portal vein
- Inferior vena cava
Superior relations of the first part of the duodenum
Epiploic foramen
Inferior relations of the first part of the duodenum
Head of the pancreas
Anterior relations of the second part of the duodenum
- Fundus of gall bladder
- Right lobe of liver
- Transverse colon
- Coils of the small intestine
Posterior relations of the second part of the duodenum
- Hilum of right kidney
- Right ureter