GI - Anatomy Clinical Correlations Flashcards
How accurately is pain localized in the parietal peritoneum? Is it more similar to visceral or dermatome pain?
Parietal peritoneum is supplied by vessels, lymphatics and nerves common to the external body wall and therefore the same modalities (pain, pressure, heat, cold) found in skin are easily localized to the body wall internally due to its precise spinal innervation.
What is rebound tenderness? What does it indicate?
Palpation of the abdominal wall that stretches the peritoneum, then abruptly letting go
-will cause severe pain in area of acute inflammation and infection, due to precise innervation of peritoneum
How accurately is pain localized to the visceral peritoneum?
Inaccurate - visceral pain
What is peritonitis? What can cause it? What are the symptoms?
Peritonitis, inflammation of the peritoneum, due to air, blood, bacteria, or fecal matter accumulating within the peritoneal cavity
Causes: abdominal lacerations, diverticulitis, ruptured appendix, or GI ulcers
Symptoms: extreme pain as the visceral and parietal layers appose one another during normal movements (walking, respiration, peristalsis).
What is ascites?
Accumulation of excess serous fluid within the peritoneal cavity is referred to as ascites.
How is ascitic fluid removed?
Removal of ascitic fluid is accomplished by paracentesis. A syringe or trocar inserted at the linea alba superior to the urinary bladder is used to “draw off” the excess fluid. Depending on the cause of the ascites, liters of fluid can accumulate that need to be removed.
Why are intraperitoneal injections useful? What is administered?
Due to the large surface area presented by the peritoneum and its absorptive nature, anesthesia and antibiotics can be administered by injecting them into the peritoneal cavity.
What is peritoneal lavage?
Washing the peritoneum with sterile water and antibiotics following abdominal surgeries, is used to reduce the occurrence of peritonitis
What is peritoneal dialysis?
In patients with renal failure, hypertonic solutions can be injected into the peritoneal cavity and then withdrawn after soluble metabolites have traversed blood vessels into the peritoneal cavity.
What are peritoneal adhesions? What are the symptoms?
Peritoneal inflammation, due to infection or endometriosis, can lead to adhesions forming between opposing layers of peritoneum, be it between adjacent layers of visceral peritoneum or between visceral and parietal peritoneum
Symptoms:
pain
impede the normal movement between organs or between the organs and the body wal
What is an adhesiotomy?
Surgical incision of peritoneal adhesions to allow for easier or pain-free movement of organs
Explain the pathology of endometriosis. Why does it occur? How is it treated?
Monthly sloughing of the endometrium, lining of the uterus, does not occur in a one way direction. The uterine tubes are open to the peritoneal cavity. Since the peritoneum provides a nutritive environment, endometrial cells which seed the peritoneal cavity develop into “islands” of endometrial tissue which respond to monthly hormonal changes, thereby effectively “spot welding” coils of intestine to one another as well as to the colon and body wall
resulting in peritoneal adhesions which are painful and may eventually impede the movement of intestinal contents.
Can be treated with adhesiotomy, or Fallopian tube ligation
How is the greater omentum protective?
The greater omentum is highly mobile and can effectively “wall off” areas which are inflamed so as to protect the other abdominal organs from the spread of infection. It also protects the abdominal organs from trauma and insulates the trunk preventing loss of heat.
What is an internal hernia?
All of the paraduodendal fossae can become confluent
Herniates at the duodenojejunal flexure during development
Mostly asymptomatic, discovered incidentally after death - autopsy, dissection
If intestines strangulate, repair is needed ASAP
When surgical repair of an internal hernia is attempted, what structures should you watch out for?
spare the inferior mesenteric vv and ascending branch of the left colic aa
What happens when patients with significant purulent ascites lie recumbent?
Fluid in the abdominopelvic peritoneal cavity can drain to the supracolic compartment by passing along the right paracolic gutter to the hepatorenal recess where an hepatorenal/subphrenic abscess can form.
An abscess here can dissect through the vertebrocostal trigone to involve the thoracic cavity.
What happens when patients with ascites turn over in sleep?
With repeated turning of the body during sleep, ascitic fluid can enter the omental bursa via the epiploic foramen and disseminate infection to the area behind the stomach (stomach bed)
What can accumulate in the omental bursa?
Fluid from other sources, i.e. accumulations of gastric fluid as a result of a perforated gastric ulcer
What is a pancreatic pseudocyst?
Fluid from an inflamed pancreas can “leaks” into the omental bursa
How is fluid in the scrotum managed via the abdominal scrotal opening?
The abdominal scrotal opening represents a potential path for extravasated fluid in the scrotum to ascend into the abdominal wall.
However, due to the previously mentioned attachments of the membranous layer of superficial fascia fluid remains in the flanks but does not progress into the lower limbs.
When doing abdominal surgery, how should you cut abdominal muscles? Why? Where is a ‘safe’ spot for abdominal incisions?
The fiber direction of the anterolateral and anterior abdominal wall musculature is arranged so that successive layers assume a non-congruent orientation, viz., vertical, horizontal, and oblique directions.
During surgery this arrangement is preserved by splitting muscles parallel to their fiber direction on a per layer basis.
Muscular fibers are never cut perpendicular to their fiber direction because they will scar, not only across the muscle fibers, but successive layers will adhere to one another impairing normal movements making them painful.
Whenever possible, abdominal incisions are placed on the mid-line (linea alba) where only fascial/tendinous tissue will be incised
What is the site of direct inguinal hernias?
Medial inguinal fossa
What is the site of indirect inguinal hernias?
Lateral inguinal fossa
Why does the lymphatic drainage of the testes play an important role in testicular cancer?
Testes drain lymph internally, to nodes located near Batson’s plexus
- allows for disseminated proliferation of malignant cancer cells
(Scrotum tends to drain more superficially, to inguinal LNs)
scrotal cancer first metastasizes to superficial inguinal nodes, while cancer of the testes metastasizes to lumbar nodes (nodes paralleling the lumbar aorta) via the lymphatics contained in the spermatic cord making it harder to diagnose its progression
What birth defect can lead to weakness of the anterior abdominal wall in the inguinal region? Why is this important?
Processus vaginalis is open in ~50% of infants until one month after birth
leads to weakness of anterior abdominal wall in the inguinal region
Contributes to indirect inguinal hernia
What is cryptorchidism?
undescended or incompletely descended testes
How is a hydrocele formed?
Fluid accumulation in the tunica vaginalis testis
- due to incomplete closure of processus vaginalis
Fluid can be from secretion of abnormal amounts of serous fluid by the serous membrane of tunica vaginalis
How is a hematocele formed?
Accumulation of blood in the scrotum in the tunica vaginalis testis
- due to trauma (blood)
- also due to incomplete closure of the processus vaginalis
What is a spermatocele?
Collection of fluid in the epididymis
- usually near its head
What is a varicocele?
Dilated veins of the pampiniform plexus.
Occurs more often on the left and can be a result of incompetent valves within the plexus or due to the angle at which the testicular v. enters the renal vein
What is testicular torsion?
Twisting of the spermatic cord due to an unattached gubernaculum
- is a medical emergency.
Twisting of the cord can lead to necrosis of the testes due to impeding vascular supply and drainage
Generally speaking, what is an abdominal wall hernia?
Hernias of the abdomen are protrusions of any portion of the abdominal contents beyond the confines of the abdominal cavity
What are the 5 types of hernias?
Epigastric Umbilical Spigelian Incisional Inguinal (direct and indirect)
Where does an epigastric hernia occur? What causes it?
Occur along the linea alba between the xipoid process and umbilicus
Can be due to gaps of CT fibers between the linea alba and rectus sheath, stresses of obesity and aging, consequence of surgical intervention
Where does an umbilical hernia occur? What is it due to?
Occur through umbilical ring
Due to weakness at site from incomplete closure of umbilical cord ligation and increased intra-abdominal pressure
Most common in neonates - associated with low birth weight
Where does a Spigelian hernia occur? What is it associated with?
Occur along the semilunar lines
Associated with obesity and in ages over 40 yrs
Where does an incisional hernia occur?
occurs at site of previously healed surgical scar
What is the definition of a direct inguinal hernia?
Protrusion of abdominal contents through the posterior wall of the inguinal canal medial to the inferior epigastric vessels
What is the rationale of direct inguinal hernia?
Transversalis fascia located between the inferior epigastric vessels and the conjoined tendon is termed “weak” fascia due to the occurrence of hernias in this area.
Fascia is located in an area known as the inguinal triangle
What is the course of herniated material with a direct inguinal hernia?
Herniated material first passes through the weak fascia of the posterior wall of the inguinal canal (located directly behind the superficial inguinal ring, lateral to the conjoined tendon, and medial to the inferior epigastric vessels), crosses the canal but does not traverse its length, and passes out through the superficial inguinal ring. Direct inguinal hernias very seldom extend into the scrotum. Forms bulge on anterior abdomen
What is the occurrence of direct inguinal hernias?
15 - 25% of inguinal hernias
Majority occur bilaterally; rare in women
Medial to inferior epigastric vessels
Through ‘weak fascia’ of Hesselbach’s triangle
Bulge in anterior wall does NOT extend into scrotum or labium
What is the definition of an indirect inguinal hernia?
Protrusion of abdominal contents through the deep inguinal ring lateral to the inferior epigastric vessels
What is the pathology/rationale behind an indirect inguinal hernia?
Weakness at the deep inguinal ring is due to:
Passage of the spermatic cord/round ligament of uterus
Failure of the processus vaginalis to completely close
What is the course of an indirect inguinal hernia?
Herniated material passes through the deep inguinal ring, traverses the entire length of the inguinal canal, protrudes through the superficial inguinal ring and extends into the scrotum or labia majora
What is the occurrence of an indirect inguinal hernia?
75 - 85% of inguinal hernias Usually occur on the right; 20X greater in males Lateral to inferior epigastric vessels Follow path of inguinal canal Extends into scrotum or labium
How can you determine the origin of an inguinal hernia?
By looking at the covering of the hernia sac
Direct hernia:
fascia that covers spermatic cord
peritoneum
transversalis fascia
Indirect hernia:
fascia that covers spermatic cord
constituents of spermatic cord
all fascial coverings in the cord too
What provides natural protection against inguinal hernias?
internal abdominal oblique and transversus abdominis muscles as they form musculo-aponeurotic arcades which clamp down or otherwise cause the area of the posterior wall of the inguinal canal to become narrower during standing, straining or coughing
What nerve do surgeons have to be careful of when performing appendectomies? Why?
surgeons performing appendectomies are careful too NOT cut the iliohypogastric nerve - provides innervation to the internal abdominal oblique and transversus abdominis muscles in the inguinal region.
- these mm provide protection against inguinal hernias
What is the deep fascia of the penis called?
Buck’s fascia.
Nope, not even kidding.
What is a Zenker’s diverticulum?
The upper 1/3 (approx.) is composed of striated muscle continuous with the inferior constrictor and innervated by the recurrent laryngeal nn. Weakness sometimes occurs in the area of the posterior pharyngo-esophageal junction. Because fibers of the inferior portion of the inferior constrictor (crico-pharyngeus/upper esophageal sphincter) diverge, a small area is left where the mucosa and adventitia can be directly opposed without intervening muscle fiber. An out-pocketing of these two opposed layers can occur, referred to as a Zenker’s diverticulum, which gathers food, fills the retrovisceral/ retroesophageal space and impedes swallowing
What are the 2 common types of hiatal/esophageal herniation?
Sliding
Paraesophageal
What is a sliding esophageal herniation? What is this association with, symptom-wise?
Sliding due to elongation of the mesenteric attachments of the esophagus to the diaphragm a portion of the lesser curvature and fundus “slide” through the esophageal hiatus into the thoracic cavity; the gastro-esophageal junction will be located superior to the diaphragm; associated with “heartburn”
What is a paraesophageal herniation? What is the symtom(s) associated with this?
Paraesophageal protrusion of the fundus of the stomach through a defect in the diaphragm next to the esophagus; the gastro-esophageal junction remains inferior the diaphragm – this is more dangerous as the fundus may strangulate.
What causes esophageal varices? What can they lead to?
Reversal of venous drainage due to circulatory blockage within the liver causes distension of the esophageal submucosal veins, resulting in the formation of esophageal varices which over time can rupture causing death. (See section on portal-caval anastomoses – Lecture 5)
What produces heartburn? What kind of pain is heartburn? What makes it worse?
Clinical correlation: GERD (Gastroesophageal reflux disease) produces “heartburn” (pyrosis) - referred pain is to the substernal region; made worse by sliding hiatal hernia
What is congenital hypertrophic pyloric stenosis? What are the symptoms? Why does Dr. Lea like this surgery so much?
grossly increased muscle layer (mainly circular) at the pylorus which does not open enough to pass stomach contents. It is palpable in the right upper quadrant just to the right of the midline and is usually identified in the first 3 - 6 weeks of life after episodes of progressive vomiting; can be surgically dilated
What can be damaged by a gastric/peptic ulcer?
Erosion of the posterior wall of the stomach due to gastric/ peptic ulcer can erode into ANY of the stomach bed structures. Erosion of the splenic a. as it courses through the substance of the pancreas can result in severe hemorrhage pancreatitis, and peritonitis.
a. Left hemidiaphragm
b. Spleen
c. Body and tail of pancreas
d. Superior pole of left kidney
e. Left suprarenal gland
f. Splenic artery
g. Transverse mesocolon
h. Left colic flexure
How can the spleen help with massive blood loss?
The spleen can expel its reservoir of blood in time of need, i.e. decreased volume or increased demand, through contraction of smooth muscle located in the capsule
Where are some locations for accessory spleens?
a. Usually small: 0.5 2.5 cm
b. Most often located in gastrosplenic ligament near hilum; can be found in tail of pancreas, mesentery proper, in proximity to the ovary or testes
What is the most frequently injured organ in the abdomen?
The spleen
What types of injuries is the spleen vulnerable to?
Susceptible to direct compression, laceration from broken ribs, blunt trauma elevating intra-abdominal pressure resulting in capsular rupture
What can be done to repair a spleen?
Capsule can be sutured; if injured too severely, splenectomy is performed to prevent fatal bleeding. Adults tolerate splenectomy well since the liver and bone marrow can assume the spleen’s functions.
What systemic diseases can necessitate a splenectomy?
Splenectomy can also be performed as a result of splenomegaly due to hypertension and various leukemias and anemias where the spleen becomes engorged & clogged due to increased white cell production or increased red cell destruction, respectively
What is a potential negative outcome of a splenic needle biopsy?
Splenic needle biopsy/spenoportography – recalling the position of the spleen related to the diaphragm, any intervention utilizing a sharp instrument has the potential to enter the thoracic cavity at the costodiaphragmatic recess resulting in pleuritis (inflammation of the pleura).
Where do peptic/duodenal ulcers occur? What happens?
Most occur in part I where stomach acid concentration is highest
Erode the posterior wall of duodenum
Can erode the gastroduodenal a. resulting in significant blood loss, peritonitis, formation of adhesions between organs located in the area, and pancreatitis.
What is pancreatitis? What causes it?
Inflammation of the pancreas
Due to:
Blocked hepatopancreatic ampulla/main pancreatic duct causing reflux of bile and/or pancreatic digestive enzyme resulting in autolysis of pancreatic tissue
trapped gallstone in ampulla or main duct; trauma; alcoholism (binge drinking)
What is the largest cause of extra hepatic biliary obstruction?
Pancreatic cancer of the head of the pancreas
What is the disease process of pancreatic cancer? What symptoms do you see?
Cancer compresses common bile duct and/or hepatopancreatic ampulla
Results in obstructive jaundice; due to backing up of bile pigments, body’s tissues become stained yellow/green
What is the result of pancreatic rupture?
Results in bleeding and autolysis of pancreatic and surrounding tissues due to dissemination of pancreatic enzymes throughout the abdomen
Do the functional internal divisions of the liver correspond to the physical lobes?
Although the quadrate and caudate lobes are described as anatomic subdivisions of the right lobe, internal functional segments do not completely correlate with established external markings. By virtue of the distribution of hepatic arteries, portal veins and hepatic ducts (hepatic triad) they functionally belong to the left lobe. These “vascularly defined” segments have greater import when considering surgical interventions, i.e. lobectomies.
What is hepatomegaly? What are some causes of it?
Hepatomegaly: increase in the overall size of the liver
Causes:
Congestive heart failure resulting in backing-up of blood due to increased resistance to blood flow through the lungs
Hepatitis (inflammation due to various causes)
Metastatic carcinoma
What is distension in the superficial neck veins a sign of? Why?
Increases in the amount of blood housed in the liver at any one time is the result of the lack of valves within the hepatic veins and IVC. Increase in central venous pressure causes the liver to become engorged with blood. Pooling of blood within the liver can be demonstrated by pushing on the right upper quadrant resulting in distension of neck veins.
What is cirrhosis? What causes it? What is the result?
Progressive hepatocellular change in the form of increased fibrosis and fat deposition due to the continued exposure to toxic substances, i.e. industrial solvents, alcohol (highest frequency)
Results in “hobnail” appearance of liver surface and portal hypertension
What is Meckel’s diverticulum?
The remnant of the yolk stalk, if present (1 2%), is located within the terminal meter of ileum on the anti-mesenteric border.
What is the rule of 2’s for Meckel’s diverticulum?
- Located within approx. 2 ft. of the distal ileum
- Occurs in 2% of the population
- 2 cm in length
- Usually discovered by the age of 2
- May contain 2 types of ectopic tissue: gastric and pancreatic mucosa
What are Peyer’s Patches? Where are they?
Collections of lymphocytic nodules
Located on anti-mesenteric border of terminal ileum
What is appendicits?
Inflammation due to blockage of lumen caused by overgrowth of epithelial lining or impaction via coprolith (fecal stone)
What is the pain pattern associated with appendicitis? Location?
Referred pain via. GVA fibers to T10 dermatome at the umbilicus
What is McBurney’s point and what does that have to do with anything clinical?
Where inflamed appendix contacts parietal peritoneum of posterior body wall, pain felt at McBurney’s point: point 2/3 the distance from the umbilicus to the ASIS
What is diverticulosis? Where does it often occur?
Evaginations of the colonic mucosa
Caused by an increase in the pressure generated by the colon to move feces of low fiber content, the wall out-pockets at points where it is weakest (where blood vessels penetrate the colon wall)
occur most often in the descending and sigmoid colon
What is diverticulitis?
Material lodged in diverticulosis pockets that becomes inflamed
What is an internal hemorrhoid? What veins are affected and why? What should you see in the stool?
Prolapse (downward displacement) of rectal mucosa affecting the internal rectal venous plexus
Veins of this plexus can become trapped by the contracted anal sphincters resulting in engorged and ulcerated veins
Due to elaborate anatomoses in this region, bleeding is mostly bright red
What causes an external hemorrhoid?
Thrombosed (clotted) veins of the external rectal venous plexus
Located directly under the skin - painful
What causes hemorrhoids, in a general sense?
Hemorrhoids in general are the result of increased intra-abdominal pressure, i.e. chronic constipation, straining at stool; pregnancy and portal hypertension (see portal caval anastomoses later in this document)
What vessel should you look out for when operating on the pancreas?
Care must be taken to not cut the middle colic vessels when surgically approaching the pancreas through the transverse mesocolon
What happens with portal vein hypertension? What can cause this?
- Collateral circulation between tributaries of the portal vein and the venae cavae (SVC & IVC) utilized when resistance to flow within the portal vein or liver becomes too great.
- Examples of resistance:
a. Cirrhosis
b. Heart disease
c. Hepatic tumor
d. Pancreatic carcinoma
e. Thrombosis
What is the portal-umbilical alternate flow to the IVC?
paraumbilical veins anastomose with veins of the anterior abdominal wall (superior & inferior epigastric) which eventually drain to the IVC and SVC.
Can lead to “Caput Medusae
What is the portal-hemorrhoidal alternate flow to the IVC?
venous plexuses of the rectum and anal canal communicate between superior rectal, middle and inferior rectal veins which are tributaries to veins which join the IVC
Can lead to “hemorrhoids”
What is the portal-retroperitoneal alternate flow to the IVC?
retroperitoneal veins draining the colon (ileocolic, right, middle and left colic), anastomose with other retroperitoneal veins (gonadal veins, veins of the pararenal fat) to drain to renal veins and ultimately the IVC.
What is the portal-azygous alternate flow to the IVC?
esophageal tributaries to the left gastric vein anastomose with esophageal veins which are drained by the azygos system to the SVC
Due to the added stress upon the esophageal veins varices can develop
What allows for venous anastomoses of the portal system?
The functionality of these anastomoses exist due to the lack of valves within these veins and the concomitant dependence of the anastomoses on the reversal of venous flow.
What is the connection between the liver and colon cancer?
Metastasis from primary colorectal cancer to the liver follows the specific path of venous drainage of the different regions of the colon
Metastasis from the appendix, cecum, ascending colon, hepatic flexure and proximal transverse colon primarily seed the right lobe of the liver via the vein of the midgut: superior mesenteric v.
Metastasis from the rectum, sigmoid, descending colon, splenic flexure, and distal transverse colon primarily seed the left lobe of the liver via the vein of the hindgut: inferior mesenteric v
The caudate and quadrate lobe receive a mixture of blood from veins of the midgut and hind gut
