Small and Large Intestine

Appendicitis can be mistaken for?

***** RETROCECAL APPENDIX **** tip may be located in right lumbar or right hypochondriac region if inflamed → pain may be mistaken for gall bladder or kidney disease Sometimes when you have pyelonephritis, you have low back pain.. appendix when it is retrocecal- you can have fever, vomiting, and also low back pain. So you always think UTI, but don't forget to think about appendix

SMALL INTESTINE: JEJUNUM AND ILEUM:

*INTRAPERITONEAL *DUODENOJEJUNAL FLEXURE TO ILEOCECAL JUNCTION NO CLEAR DEMARCATION BETWEEN JEJUNUM AND ILEUM *FREELY MOBILE ATTACHED TO POSTERIOR ABDOMINAL WALL BY MESENTERY

Suspensory muscle of duodenum (ligament of Treitz):

*Is an important anatomical landmark of the duodenojejunal flexure, separating the upper and lower gastrointestinal tracts.

How do surgeons identify the cecum in a colonoscopy?

- During colonoscopy, the ileocecal valve is used, along with the appendiceal orifice, in the identification of the cecum. This is important as it indicates that a complete colonoscopy has been performed.

What is the only site in the gastrointestinal tract that is used for Vitamin B12 and bile acid absorption.

- The ileocecal valve is distinctive because it is the only site in the gastrointestinal tract that is used for Vitamin B12 and bile acid absorption.

A Lower GI series

A lower gastrointestinal series is a medical procedure used to examine and diagnose problems with the human colon. Radiographs are taken while barium sulfate, a radiocontrast agent, fills the colon via an enema through the rectum. Barium enema- a contrast passes through- it can detect changes or abnormalities in the large intestine (colon). An enema is the injection of a liquid into your rectum through a small tube. You can determine if there is an infection.. need to treat . Can also cut the two portions and tie - invagination of one part of intestine to the other

Megacolon end result

ABSENCE OR DESTRUCTION OF NERVE SUPPLY TO COLON submucosal plexus (of Meissner) myenteric plexus (of Auerbach) ↓ dilatation & disturbance in mobility of involved segment ↓ intestinal obstruction

What part of colon is retroperitoneal?

Ascending and descending

Blood supply ascending and transverse colon

Ascending and transverse up to the left colic flexure: Branches from the SMA a) Jejunal and ileal branches b) Ileocolic c)Right colic artery d)Middle colic artery

Melena versus Hematochezia

Bleeds that originate from the lower gastrointestinal tract (such as the sigmoid colon and rectum) are generally associated with the passage of bright red blood, or hematochezia. Only blood that originates from a more proximal source (such as the small intestine), or bleeding from a lower source that occurs slowly enough to allow for enzymatic breakdown, is associated with melena. For this reason, melena is often associated with blood in the stomach or duodenum (upper gastrointestinal bleeding), for example by a peptic ulcer. A rough estimate is that it takes about 14 hours for blood to be broken down within the intestinal lumen; therefore if transit time is less than 14 hours the patient will have hematochezia, and if greater than 14 hours the patient will exhibit melena. One often-stated rule of thumb is that melena only occurs if the source of bleeding is above the ligament of Treitz although, as noted below, exceptions occur with enough frequency to render it unreliable.

Acute appendicitis clinical diagnosis

CLINICAL PICTURE VAGUE EPIGASTRIC PAIN ↓ PERIUMBILICAL PAIN ↓ RIGHT LOWER QUADRANT PAIN PAIN ON PRESSURE OVER McBURNEY'S POINT TREATMENT SURGERY

Appendicitis clinical picture

CLINICAL PICTURE VAGUE EPIGASTRIC PAIN ↓ PERIUMBILICAL PAIN ↓ RIGHT LOWER QUADRANT PAIN PAIN ON PRESSURE OVER McBURNEY'S POINT TREATMENT SURGERY

The large intestine- caliber

Caliber - the internal diameter is larger.

Rectum and Anal canal

Continuous with sigmoid colon at the level of S3 vertebra Rectum is continuous with the anal canal -rectal CA is common

Blood supply descending colon and sigmoid colon

Descending Colon and Sigmoid colon Inferior mesenteric Artery branches Left colic artery Branches to descending colon Sigmoid artery

What is diverticulosis?

Diverticulosis happens when pouches (diverticula camera.gif) form in the wall of the colon camera.gif. If these pouches get inflamed or infected, it is called diverticulitis. Diverticulitis can be very painful.

What causes diverticulosis? What causes Diverticulitis?

Doctors aren't sure what causes diverticula in the colon (diverticulosis). But they think that a low-fiber diet may play a role. Without fiber to add bulk to the stool, the colon has to work harder than normal to push the stool forward. The pressure from this may cause pouches to form in weak spots along the colon. Doctors aren't sure what causes diverticulitis. Bacteria grow in the pouches, and this can lead to inflammation or infection.

omental appendages

External feature of large intestine: Epiploic appendages are 1-2 cm thick and 0.5-5 cm long, each supplied by one or two small colonic end-arteries and a small draining vein. They are described as small, physiologic peritoneal fat pouches which are attached to the external surface of the colon by vascular stalks. "fatty tags"

haustra

External feature of large intestine: The haustra (singular haustrum) of the colon are the small pouches caused by sacculation (sac formation), which give the colon its segmented appearance. The teniae coli run the length of the large intestine.

Evidence of what color blood indicated upper GI problem?

For example, bloody vomit or melena, black tarry stools, usually indicate a gastrointestinal bleed from a location in the upper gastrointestinal tract. In contrast, hematochezia, bright red blood or clots in the stool, usually indicates gastrointestinal bleeding from the lower part of the gastrointestinal tract.

Blood supply of GI

Foregut - supplied by the celiac trunk Midgut - supplied by superior mesenteric artery Hindgut - supplied by inferior mesenteric artery

Main culprit of Cervical CA

Human papillomavirus infection- main culprit of cervical CA- main cause is unprotected sex- same can happen in colon- anal intercourse. As well as CA of throat.

Cecum: Location

INTRAPERITONEAL 2.5 inches long LOCATION right inguinal region inferior to ileocecal junction

Appendix location

INTRAPERITONEAL 3-5" long can be mapped out on body surface at McBurney's point

Meckel's diverticulum

Ileal (Meckel's) Diverticulum: Is a congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the omphalomesenteric duct (also called the vitelline duct or yolk stalk) Anytime you think of appendicitis , always eep in mind it can be Meckel's

How is the ileocecal valve difference than sphincter?

Ileocecal valve different than sphincter- importance b/c feces enters cecum and try to return, the valve is closed! If feces return to ilium- compromises- voiding feces

What separates the small intestine from the colon?

Ileocecal valve: Separates the small intestine from the colon. Prevents backflow of feces.

Where does the ileum end?

Ileum ends at the ileocecal (ileocolic)junction Enters ascending colon at "ileocolic junction"

The minor duodenal papilla

In 10% of people, the minor duodenal papilla is the prime duct for drainage of the pancreas, although in others it may not be present at all The minor duodenal papilla represents the remnants of the opening of the accessory pancreatic duct, which drains the dorsal pancreatic bud during fetal development.

Diagnosis of melena

In acute cases, with a large amount of blood loss, patients may present with anemia or low blood pressure. However, aside from the melena itself, many patients may present with few symptoms. Often, the first approach is to use endoscopy to look for obvious signs of a bleed. In cases where the source of the bleed is unclear, but melena is present, an upper endoscopy is recommended, to try to ascertain the source of the bleed.

Appendicitis clinical diagnosis

In particular, it presents at McBurney's point, 1/3 of the way along a line drawn from the anterior superior iliac spine to the umbilicus. Typically, point (skin) pain is not present until the parietal peritoneum is inflamed, as well. Fever and an immune system response are also characteristic of appendicitis.

Diverticulitis

Infection and inflammation of the diverticula- can be perforated if you don't treat with antibiotics; difference is location. In colon versus ileum of small intestine. Pain can be diffuse, or localized..So it seems like meckels is the ileum only and is congenital. Diverticulitis itself is in the colon only and it's not congenital

ILEAL (MECKEL'S) DIVERTICULUM

It is the most common malformation of the gastrointestinal tract and is present in approximately 2% of the population,[1] with males more frequently experiencing symptoms. RULE OF 2'S 2% of population 2 feet from ileocecal junction 2 inches long 2 tissues: gastric & pancreatic 2 complications: ulceration & obstruction

Jejunum

Jejunum begins at the duodenojejunal junction. Often empty Plicae circulates Mesentery - a fold of peritoneum attaches the jejunum and ileum to the posterior abdominal wall.

Cecum

Lies in the iliac fossa inferior to the junction of the terminal ileum and cecum No mesentery No omental appendices Teniae coli are prominent here Blood - anterior and posterior cecal arteries which are branches from ileocolic artery.

Causes of Megacolon

MAY BE CONGENITAL Hirschprung's Disease or Aganglionic Megacolon MAY BE ACQUIRED Chagas disease by Trypanosoma cruzi TREATMENT surgery

muscular wall of appendix

MUSCULAR WALL inner circular outer longitudinal *3 TENIA COLI → CONVERGE AT BASE OF APPENDIX TO FORM A COMPLETE OUTER LONGITUDINAL MUSCLE LAYER FOR THE APPENDIX

Muscular wall of large intestine

MUSCULAR WALL outer longitudinal layer arranged in 3 separate bands from cecum to sigmoid colon → tenia coli complete layer in appendix and rectum

Megacolon

Megacolon is an abnormal dilation of the colon (also called the large intestine). The dilation is often accompanied by a paralysis of the peristaltic movements of the bowel. Megacolon means "huge" No innervation= becomes distended

melena

Melena refers to the dark black, tarry feces that are associated with upper gastrointestinal bleeding. The black color and characteristic strong odor are caused by hemoglobin in the blood being altered by digestive enzymes and intestinal bacteria.

mesenteric proper

Mesentery of the small intestine (mesentery proper) The mesentery of the small intestine is a large and broad fan-shaped mesentery that is attached to the jejunum and ileum of the small intestine, connecting them to the posterior abdominal wall.

pyelonephritis versus appendicitis

Need to be careful of pyelonephritis versus appendicitis Clinical manifestation can be confused with a lot of abdominal thrusts.

In females with abdominal pain and lack of menstruation, what is a differential diagnosis to always think about?

No menstruation , or small amount= THINK ECTOPIC pregnancy- if not diagnosed, you can die from shock The fertilized egg can't survive outside the uterus. If left to grow, it may damage nearby organs and cause life-threatening loss of blood. Symptoms include pelvic pain and vaginal bleeding.

Duodenum is divided into how many parts based on . POSITION?

PARTS Superior (First) - 2 inches Descending (Second) - 3 inches Horizontal (Third) - 4 inches Ascending (Fourth) - 1 inch

Acute appendicitis patho

PATHOPHYSIOLOGY OBSTRUCTION OR OCCLUSION OF LUMEN fecalith (enterolith) hyperplasia of the lymphoid follicles ↓ RETENTION OF SECRETIONS ↓ SWELLING OF APPENDIX AND ITS PERITONEAL COVERING ↓ COMPRESSION OF BLOOD SUPPLY ↓ THROMBOSIS ↓ GANGRENE OF WALL ↓ PERFORATION OR RUPTURE ↓ PERITONITIS

Parasympathetic innervation of GI

Parasympathetic nerve: Foregut and midgut - Vagus nerve Hindgut - Pelvic Splanchnics - S2,3,4 also contain parasympathetic nerve fibers.

Protection of colon

Protection of colon- large intestine has its own protection so more local lymphoid tissue= appendix.. inflammation. Removed if diagnosed on time. otherwise, feces into abdominal cavity

Duodenum

RETROPERITONEAL except 1st inch of first part LOCATION epigastric and umbilical regions C-SHAPED curves around head of pancreas *RECEIVES OPENINGS OF CBD & PANCREATIC DUCTS*

If part of colon diseased...

Resection- operation that removes tissue or part of an organ. Bowel resection , also called partial colectomy, removes a diseased or damaged part of the colon or rectum. ... Then healthy parts of the colon or rectum are sewn back together.

Site of greater part of digestion and absorption of food

Small intestine *longest part of the GIT (~21 feet long) (from pylorus to ileocecal junction)

Sympathetic innervation of GI

Sympathetic Foregut - Greater splanchnic T5-T9 Midgut - Lesser splanchnic - T10-T11 Hindgut - Lumbar splanchnic - L1-L4

While the base of the appendix is at a fairly constant location—2 cm below the ileocecal valve, the tip of the appendix can be variably located

TIP OF APPENDIX pelvic retrocecal paracecal ileal

Teniae coli

Teniae coli - 3 thickened bands of longitudinal muscle fibers

The major duodenal papilla

The major duodenal papilla is an opening of the pancreatic duct into the duodenum. The major duodenal papilla is, in most people, the primary mechanism for the secretion of bile and other enzymes that facilitate digestion. It is surrounded by the sphincter of Oddi, and receives a mixture of pancreatic enzymes and bile from the Ampulla of Vater, which drains both the pancreatic duct and biliary system. The junction between the foregut and midgut occurs directly below the major duodenal papilla.

Causes of melena

The most common cause of melena is peptic ulcer disease. However, any bleeding within the upper gastrointestinal tract or the ascending colon can lead to melena. Melena may also be a complication of anticoagulant medications, such as warfarin. Causes of upper GI bleeding that may result in melena include malignant tumors affecting the esophagus, stomach or small intestine, hemorrhagic blood diseases, such as thrombocytopenia and hemophilia, gastritis, esophageal varices, Meckel's diverticulum and Mallory-Weiss syndrome. Causes of "false" melena include iron supplements, Pepto-Bismol, Maalox, and lead, blood swallowed as a result of a nose bleed (epistaxis), and blood ingested as part of the diet, as with consumption of black pudding (blood sausage), or with the traditional African Maasai diet, which includes much blood drained from cattle. Melena is often a medical emergency as it arises from a significant amount of bleeding. Urgent care is required to rule out serious causes and prevent potentially life-threatening emergencies. A less serious, self-limiting case of melena can occur in newborns two to three days after delivery, due to swallowed maternal blood.

most common symptoms of Meckel's diverticulum

The most common presenting symptom is painless rectal bleeding such as melena-like black offensive stools, followed by intestinal obstruction, volvulus and intussusception.

Sphincter of Oddi function

The sphincter of Oddi (also hepatopancreatic sphincter or Glisson's sphincter), abbreviated as SO, is a muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of Vater into the second part of the duodenum.

suspensory muscle of duodenum

This division is used to mark the difference between the upper and lower gastrointestinal tracts, which is relevant in clinical medicine as it may determine the source of bleeding in the gastrointestinal tract -also upper versus lower GI obstruction

What is toxic megacolon (not on exam)

Toxic megacolon (megacolon toxicum) is an acute form of colonic distension. It is characterized by a very dilated colon (megacolon), accompanied by abdominal distension (bloating), and sometimes fever, abdominal pain, or shock.

Which part of colon is intraperitoneal?

Transverse and Sigmoid colon

If appendicitis not diagnosed

Untreated, the appendix may rupture, leading to peritonitis, followed by shock, and, if still untreated, death.

Meckel's diverticulum is mainly asymptomatic, however, when inflamed....

WHEN INFLAMED ↓ MAY BE MISTAKEN FOR ACUTE APPENDICITIS Occasionally, Meckel's diverticulitis may present with all the features of acute appendicitis. Also, severe pain in the epigastric region is experienced by the patient along with bloating in the epigastric and umbilical regions. At times, the symptoms are so painful that they may cause sleepless nights with acute pain felt in the foregut region, specifically in the epigastric and umbilical regions.

Intussusception ?

Wall of intestine makes a fold and gets into another portion, compromise blood flow and feces. Can happen in small intestine, here is last portion of small intestine into cecum. Provoke intestinal obstruction so no advance of feces. Most common..so can also cause bleeding or tumor which of course causes pain. Bowel sounds increased intensity of bowel sounds. First determine if they are normal or not.. intestine is fighting the obstruction so working hard. Eventually exhaustion trying to fight and iliac causes intestine not to move- increased tonicity of the muscle causes spastic ilia. DECREASED can also think of an obstruction. No bowel sounds= obstruction so it's the abnormality of bowel sounds.

Duodenal ulcers

almost always due to H. pylori infection LOCATION superior (first) part chronic untreated or intractable cases ↓ ulcers may penetrate the whole thickness of duodenal wall and perforate PERFORATION IN ANTERIOR WALL ↓ spillage of duodenal contents into greater sac ↓ generalized peritonitis PERFORATION IN POSTERIOR WALL ↓ erosion of gastroduodenal artery → hemorrhage into lesser sac → greater sac MEDICAL/SURGICAL MANAGEMENT

Contraction of SUSPENSORY MUSCLE OF DUODENUM (LIGAMENT OF TREITZ)causes?

contraction → duodenojejunal flexure angle widens ↓ facilitates passage of food from duodenum to jejunum

root of mesentery

duodenojejunal flexure → ileocecal junction & right sacroiliac joint allows entrance and exit of bv's, nn., & lymph vessels

vermiform appendix

lymphoid aggregates also pictured

Muscular coat of small intestine

muscular coat outer longitudinal layer inner circular layer

Diverticulosis

outpouchings of lining mucosa through circular muscle layer occur at weakest points in the wall → where blood vessels pierce the wall

volvulus

rotation of sigmoid colon around its mesentery ↓ intestinal obstruction may correct itself spontaneously may continue and become gangrenous ↓ SURGERY

INTUSSUSCEPTION:

telescoping of a proximal segment of intestine into the lumen of an adjoining distal segment ↓ intestinal obstruction TYPES ileoileal ileocolic - most common colocolic

invagination

the action or process of being turned inside out or folded back on itself to form a cavity or pouch.

appendix also called

vermiform appendix- meaning "worm-shaped"

JEJUNUM AND ILEUM: DIFFERENCES

• Jejunum has little fat inside the mesentery than ileum. Therefore, the visibility of the vessels of jejunum is more accounting for peritoneal windows than ileum. • Unlike the jejunum, ileum has more Payers' patches, solitary and aggregated lymph nodes, and other cells of the immune system. • Ileum mainly absorb vitamin B12, bile salt, and whatever the products of digestion that were not previously absorbed by jejunum, whereas jejunum absorb monosaccharides and amino acids.

Some more differences ...

• Jejunum has simpler blood supply, whereas ileum wall contains more arterial branches to supply more blood. • Jejunum makes the middle part while ileum makes the last part of the small intestine. • Jejunum is in the upper abdomen, to the left of the midline, whereas ileum is in the lower part of the abdomen and pelvis.

more differences

• The lumen of jejunum is wider than that of ileum. • Jejunum has little fat in the mesentery than ileum. • The inner surface of jejunum has numerous transverse folds while ileum has very few. Because of that, jejunum is thick walled while ileum is thin walled. • Jejunum has longer vasa recta whereas, ileum has shorter vasa recta.