Lecture 10 - Alimentary 2 Flashcards
Where does small intestine extend
Pylorus to ileocaecal valve
What does the small intestine consist of (3)
Duodenum, jejunum and ileum
What is the function of the small intestine
Digestion and absorption of nutrients
The entire duodenum is retroperitoneal true or false?
False
What section of the duodenum is not retroperitoneal?
The first 2-3 cms which are attached to the greater and lesser omenta
What is the shape of the duodenum? (2)
C-shaped with 4 parts that curve around the head of the pancreas
Where does the duodenum sit?
Above the level of the umbilicus
What are the permanent circular folds of the duodenum called?
Plicae
Where are the plicae most pronounced?
In the proximal duodenum
What do the plicae look like in contrast medium x-rays?
Feathery
What vein and duct are posterior to the duodenum?
Portal vein and bile duct
What organs are anterior to the superior duodenum (2)
Quadrate lobe of the liver and gallblader
What is the first part of the duodenum called in x-rays
Duodenal cap
Why is the duodenal cap shorter than it actually is in x-rays?
It has an oblique orientation
What is medial to the descending/second part of the duodenum
Head of the pancreas
Where do the bile duct and main pancreatic ducts empty into the duodenum?
The greater duodenal papilla
Where would the lesser duodenal papilla be anatomically if it existed for the accessory pancreatic duct
2 cm above the greater papilla
What is posterior to the descending duodenum?
Hilum of the right kidney
What is posterior to the horizontal/third part of the duodenum?
Upper right psoas
What vessels are anterior to the horizontal duodenum
superior mesenteric vessels
Where do the superior mesenteric vessels pass between
The uncinate process and the head of the pancreas
What is posterior to the ascending/fourth part of the duodenum?
Upper left psoas
Where is the duodenojejunal junction
The level of L2 just medial to the left kidney (easy to recognise by the appearance of a mesentery supporting the jejunum.
The duodenum is in general posterior to the transverse colon, true or false?
True
What fraction of the length of the small intestine are the jejunum and ileum
2/5 and 3/5
Where is the jejunum largely located?
Umbilical region
Where is the ileum mainly located?
Lower abdomen and pubic regions
Where is the first loop of jejunum usually coiled?
Between the left transverse colon and left kidney
Where does the jejenum and ileum extend?
From the duodenal flexure to the ileocaecal valve.
The transition from the ileum to the caecum is gradual true or false?
True
What is the mesentery attachment of the jejunum and ileum to the posterior abdominal wall called?
The root of mesentery
Which direction does the root of mesentery run?
Upper left to lower right
What is the shape of root of mesentery?
Fan-shaped
The internal transverse folds of the jejunum and ileum are temporary like the stomach folds, true or false?
False, they are not obliterated by distension
What comprises the walls of the jejunum and ileum (4)
Mucosa with villi, thin muscularis mucosa, submucosa and thick external muscle
Where do the vasa recta of the jejunum arise from?
Branches of the superior mesenteric artery
The jejunum has longer mesentery vasa recta then the ileum with few anastamoses, true or false?
True
The ileum has larger and longer folds than the jejunum, true or false?
False
The jejunum is thinner and less vascular walled than the ileum, true or false?
False
The mesentery of the ileum is less fatty than the jejunum true or false?
False
The jejunum has small and few aggregated lymph follicles (Payer’s patches), true or false?
True
The jejunum has longer villi true or false?
True
What is the large intestine comprised of? (8)
Caecum, appendix; ascending, descending, transverse, sigmoid colon, rectum, anus
What is the function of the large intestine?
Absorption of water and ions
What are the sacculation/haustra
Regular expanded areas of the colon interspersed with constrictions
Where are the taenia not present
Appendix and rectum junction
What are the taenia coli
3 thickenings of the longitudinal part of the external muscle
What are three features of the large intestine?
Sacculation, taenia coli and epiploic/omental appendices
Where are the epiploic appendices present
Transverse and sigmoid colon
The appendix and rectum junction have epiploic appendices true or false?
False
Where is the caecum located?
In the right iliac fossa
The caecum is attached by mesentery true or false?
False
What usually surrounded caecum?
Peritoneum
When is the caecum not surrounded by the peritoneum?
Where it connects with the ileum and ascending colon
What is the caecum?
A blind intestinal pouch suspended from the ascending colon
What is behind the caecum?
The retrocaecal recess
Where is the junction between the caecum and ascending colon?
At the level of the ileocaecal valve
What likely facilitates the reflux of the bolus back into the ileum?
The tightening of frenulae rather than the contraction of the poorly developed muscle of the horizontal ileocaecal valve
What is the anatomical description of the horizontal ileocaecal valve
Posteromedial
What does the horizontal ileocaecal valve consist of?
two flaps called valves whose edges taper into horizontal elevations/frenulae
What is the gastroileal reflex
When food in the stomach initiates contraction of the small intestine and thus expulsion of ileal contents into the caecum
Where is the appendix often located? (3)
Retrocaecal recess or hanging down over the pelvic brim or close to the opening of the uterine tube in females
What point does the appendix open into the caecum? (2)
McBurney’s point - junction of lateral and middle thirds of line joining umbilicus and anterior superior iliac spine (ASIS)
What is the appendix suspended on and what is this suspension attached to?
Mesoappendix, attached to the ileal mesentary
The appendix has a ring of lymphatic nodules in the mucosa and submucosa true or false?
True
Where does the ascending colon extend?
From the ileocaecal valve to the right colic flexure
Where is the right colic flexure? (3)
Anterior to the right kidney and descending duodenum and behind the fundus of the gallbladder
The ascending colon is always retroperitoneal true or false?
False, many up to 50% of individuals have ascending or even descending colon attached with little mesentery
What suspends the transverse colon?
Transverse mesocolon
Where is the transverse colon suspended between and how?
Colic flexures in an inverted arch
What does the transverse mesocolon attach to? (2)
Greater omentum and pancreas
Where is the anatomical position of the left colic flexure
anterior to the left kidney and below the spleen and pancreas
What attaches the left colic flexure to the diaphragm?
Phrenicocolic ligament
What is the function of the phrenicocolic ligament?
Provides support for the spleen
What is the pathway of the phrenicocolic ligament?
It passes laterally under the spleen and is continuous with the splenocolic ligament
Where does the descending colon span?
The left colic flexure to the pelvic inlet
What is the pathway of the descending colon (3)
Down the abdominal wall
Turns medially into left iliac fossa
Crosses structures
What structures does the descending colon cross (2)?
Testicular/ovarian vessels and external iliac vessels
Where does the sigmoid colon extend?
From the pelvic brim to S3 (middle of sacrum)
What shape does the sigmoid colon form?
A V-shape
Where does the sigmoid colon reside?
In the intersigmoidal recess behind the sigmoid mesocolon
What does the sigmoid colon overly? (2)
Left ureter and external iliac vessels.
