Combined 02 clinical training--anatomy


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  • Every cell in the body requires nutrition. This includes not only oxygen, but also other nutrients, which must be ingested. Most foods are composed of larger molecules that cannot be readily absorbed; therefore, they must be broken down into smaller molecules
  • The digestive process involves both mechanical action such as that provided by the teeth, stomach and intestines, and chemical action provided by fluids that help digestion. Additionally, the cells produce waste that must be removed. These functions of nutrition and waste removal are performed by the systemic or peripheral circulatory system, and final removal of waste or “cleaning” of the blood is performed by the kidneys. It is important to understand that the digestive system is an element of the human body that is crucial for the function of all anatomical systems.
  • Peristalsis is the rhythmic contraction of circular and longitudinal smooth muscles used to propel contents through the digestive tract. In much of the  gastrointestinal tract ,  smooth muscles  contract in sequence to produce a peristaltic wave which forces a ball of  food  (called  bolus  while in the  esophagus  and gastrointestinal tract and  chyme  in the  stomach ) along the gastrointestinal tract. Peristaltic movement is initiated by circular smooth muscles contracting behind the chewed material to prevent it from moving back into the mouth, followed by a contraction of longitudinal smooth muscles which pushes the digested food forward.
  • In biology and medicine, epithelium is a  tissue  composed of a layer of  cell s. The lamina propria (more correctly lamina propria mucosae ) is a thin layer of  loose connective tissue  which lies beneath the  epithelium  and together with the epithelium constitutes the  mucosa . the thin layer of  smooth muscle  found in most parts of the  gastrointestinal tract , located outside the  lamina propria mucosae  and separating it from the  submucosa .
  • Peritoneal cavity The peritoneal cavity is a potential space between the parietal  peritoneum  and visceral peritoneum.
  • The cavity bound by the peritoneum is known as the peritoneal cavity (Figure 8). The space outside the peritoneum, but still within the abdominal cavity, is known as the extraperitoneal space. The extraperitoneal space can be divided into three areas, all connected: an anterior, a lateral, and a posterior area. The anterior region is known as the preperitoneal space, the posterior region is known as the retroperitoneal space (Figure 8.) All organs found in the retroperitoneal space are known as retroperitoneal organs. As a very general rule, all retroperitoneal organs -some of which may be related to the peritoneum -do not have a mesentery, therefore they are not mobile. An organ behind the parietal peritoneum is classified as being retroperitoneal. Retroperitoneal organs are fixed to the posterior abdominal wall. Also as a very general rule, most organs of the digestive system contained within the peritoneal cavity do have a mesentery and are therefore mobile. The presence of mobility defines an organ as intraperitoneal.
  • The mesenteries are double layers of serous membrane, composed of peritoneal membranes which have folded against each other. These mesenteries connect and hold gastrointestinal organs in place and attach blood vessels and nerves. They also, with their fatty coverings, protect and insulate the organs. The greater omentum , for instance, hangs in front of the intestines acting as an insulator and shock absorber.
  • Seen here is a loop of bowel attached via the mesentery. Note the extent of the veins and arteries. There is an extensive anastomosing arterial blood supply to the bowel, making it more difficult to infarct. Also, the extensive venous drainage is incorporated into the portal venous system heading to the liver.
  • The stomach : The stomach is composed of several regions and structures:   The gastroesophageal region (a.k.a. cardia) mentioned above.   The fundus is the blind portion of the stomach above its junction with the Esophagus. This portion is thin walled compared to the rest of the stomach and has few secretory cells. As the bolus of food enters this area first some action of salivary amylase may continue briefly.   The body of the stomach. This is where extensive gastric pits located which possess the secretory cells of the stomach.   The pylorus . This narrowed region leads through the pyloric sphincter into the duodenum . 3-layered muscularis - an oblique layer in addition to the longitudinal and transverse layers. The three layers produce a churning and liquefying effect on the chyme in the stomach.
  • The pyloric sphincter is a structural sphincter which regulates the onward progression of materials from the stomach into the duodenum, and helps to prevent their return to the stomach.
  • Combined 02 clinical training--anatomy

    1. 1. The Next Era in GI Surgery BioDynamix TM Anastomosis The ColonRing Clinical Training Team ANATOMY
    2. 2. The Digestive System - Purpose <ul><li>Every cell in the body needs nutrition . This includes not only oxygen , but also other nutrients that must be ingested. </li></ul><ul><li>Foods are composed of larger molecules not readily absorbed. They are broken down into smaller pieces. </li></ul>
    3. 3. The Digestive System - Purpose <ul><li>The digestive system breaks down foods (carbohydrates, fats and proteins) into molecules that are absorbed by the small intestine & carried to the liver by the blood stream for further processing. </li></ul><ul><li>After processing by the liver, these molecules are distributed to the body by the cardiovascular system . </li></ul><ul><li>Digestion is the conversion of complicated foodstuffs to their simplest forms : six-carbon sugars, amino acids, and fatty acids. </li></ul>
    4. 4. Overview of the Digestive System <ul><li>Digestive organs are divided into two groups: </li></ul><ul><ul><li>Alimentary canal </li></ul></ul><ul><ul><ul><li>Mouth, pharynx, and esophagus </li></ul></ul></ul><ul><ul><ul><li>Stomach, small intestine, and large intestine </li></ul></ul></ul><ul><ul><li>Accessory digestive organs </li></ul></ul><ul><ul><ul><li>Teeth and tongue </li></ul></ul></ul><ul><ul><ul><li>Gallbladder, salivary glands, liver, and pancreas </li></ul></ul></ul>
    5. 5. Overview of the Digestive System
    6. 6. Digestive Processes
    7. 7. Digestive Processes <ul><li>Ingestion – occurs in the mouth </li></ul><ul><li>Propulsion – movement of food </li></ul><ul><ul><li>Peristalsis – major means of propulsion </li></ul></ul>
    8. 8. Peristalsis <ul><li>Peristalsis is the rhythmic contraction of smooth muscle (circular and longitudinal) to propel contents through the digestive tract from the mouth to the anus. </li></ul>
    9. 9. Digestive Processes <ul><li>Ingestion – occurs in the mouth </li></ul><ul><li>Propulsion – movement of food </li></ul><ul><ul><li>Peristalsis – major means of propulsion </li></ul></ul><ul><li>Mechanical digestion – prepares food for chemical digestion </li></ul><ul><ul><li>Chewing, churning of food in stomach, segmentation </li></ul></ul><ul><li>Segmentation is rhythmic local constrictions of intestine </li></ul>
    10. 10. Digestive Processes <ul><li>Chemical digestion – </li></ul><ul><ul><li>complex molecules broken down to chemical components </li></ul></ul><ul><ul><ul><li>Mouth </li></ul></ul></ul><ul><ul><ul><li>Stomach </li></ul></ul></ul><ul><ul><ul><li>Small intestine </li></ul></ul></ul><ul><li>Absorption – </li></ul><ul><ul><li>transport of digested nutrients </li></ul></ul><ul><li>Defecation – </li></ul><ul><ul><li>elimination of indigestible substances as feces </li></ul></ul>
    11. 11. Histology of the Alimentary Canal Wall <ul><li>Usually four layers from esophagus to rectum: </li></ul><ul><ul><li>The mucosa – innermost layer, containing small glands and lymphatic nodules </li></ul></ul><ul><ul><ul><li>Epithelium - epithelium is a  tissue  composed of a layer of  cell s . </li></ul></ul></ul><ul><ul><ul><li>Lamina propria - is a thin layer of  loose connective tissue which lies beneath the  epithelium . </li></ul></ul></ul><ul><ul><ul><li>Muscularis mucosae – is a thin layer of smooth muscle located outside the lamina propria . </li></ul></ul></ul>
    12. 12. Histology of the Alimentary Canal Wall <ul><ul><li>The submucosa – external to the mucosa </li></ul></ul><ul><ul><ul><li>Thin layer of connective tissue containing blood and lymphatic vessels, nerve fibers </li></ul></ul></ul><ul><ul><ul><li>Strongest layer of the large intestine due to collagen fibers </li></ul></ul></ul><ul><ul><li>The muscularis externa – external to the submucosa </li></ul></ul><ul><ul><ul><li>Two layers </li></ul></ul></ul><ul><ul><ul><ul><li>Circular smooth muscle – inner layer </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Longitudinal smooth muscle – outer layer </li></ul></ul></ul></ul><ul><ul><li>The serosa – the outermost layer </li></ul></ul><ul><ul><ul><li>Is the visceral peritoneum </li></ul></ul></ul><ul><ul><ul><li>Absent in the Esophagus </li></ul></ul></ul><ul><ul><ul><li>Absent in most of Rectum </li></ul></ul></ul>
    13. 13. The Peritoneal Cavity and Peritoneum <ul><li>Peritoneum – a serous membrane that forms a sac within the abdomen: </li></ul><ul><ul><li>Parietal peritoneum – lines the body wall </li></ul></ul><ul><ul><li>Visceral peritoneum – surrounds digestive organs </li></ul></ul><ul><li>Peritoneal cavity – </li></ul><ul><ul><li>The peritoneal cavity is a potential space between the parietal  peritoneum  and visceral peritoneum . </li></ul></ul>
    14. 14. The Peritoneal Cavity and Peritoneum <ul><li>Peritoneal organs </li></ul><ul><ul><li>Lie within the peritoneal cavity </li></ul></ul><ul><ul><li>Digestive organs that keep their mesentery </li></ul></ul><ul><li>Retroperitoneal organs </li></ul><ul><ul><li>Lie behind the parietal peritoneum </li></ul></ul>
    15. 15. The Peritoneal Cavity and Peritoneum <ul><li>Mesentery – a double layer of peritoneum </li></ul><ul><ul><li>Holds organs in place </li></ul></ul><ul><ul><li>Provides a route for circulatory vessels (arteries, veins, and lymphatics) and nerves </li></ul></ul><ul><ul><li>Provides sites for fat storage </li></ul></ul>
    16. 16. Mesenteries <ul><li>Superficial view of abdominal organs </li></ul>
    17. 17. Mesenteries <ul><li>Lesser omentum attaches to lesser curvature of stomach </li></ul>
    18. 18. Mesenteries <ul><li>Greater omentum – a “fatty apron” of peritoneum </li></ul><ul><ul><li>Portion connecting stomach with transverse colon is the gastrocolic ligament </li></ul></ul><ul><ul><li>Remaining portion attaches to anterior surface of transverse colon and hangs down anterior to rest of bowel </li></ul></ul><ul><li>(Picture shows greater omentum and transverse colon reflected) </li></ul>
    19. 19. Mesenteries – Small Bowel
    20. 20. Mesenteries <ul><li>( Sagittal section through the abdominopelvic cavity ) </li></ul><ul><li>Mesenteries attach to the posterior abdominal wall. </li></ul><ul><li>Mesocolons are mesenteries of the large intestine. </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.10d
    21. 21. Mesenteries - Mesos of the Colon <ul><li>The appendix, part of the cecum, the transverse colon and the sigmoid colon present with a mesentery or meso , and they are easily moved out of the way during surgery. </li></ul><ul><li>The ascending and the descending colon do not have a mesentery or meso but are attached to the posterior abdominal wall by a reflection of their serosal covering from which they must be separated during surgery. </li></ul><ul><li>The mesorectum is actually a misnomer as the attachment of the rectum is not covered by peritoneum, but the name persists due to common usage. </li></ul>
    22. 22. Anatomy – Abdominal Organs
    23. 23. The Stomach Figure 22.18a
    24. 24. Pyloric Sphincter
    25. 25. The Small Intestine <ul><li>Longest portion of the alimentary canal </li></ul><ul><ul><li>~ 4-7 m (20 ft.) long </li></ul></ul><ul><ul><li>Site of most enzymatic digestion and absorption </li></ul></ul><ul><li>Three subdivisions </li></ul><ul><ul><li>Duodenum - ~ 25 cm (10 in.) long – “12 fingerbreadths) </li></ul></ul><ul><ul><li>Jejunum - ~ 1-2 m (3-6.5 ft.) long </li></ul></ul><ul><ul><li>Ileum – 2-4 m (6.5-13 ft.) long </li></ul></ul>
    26. 26. The Duodenum <ul><li>Receives gastric contents via the pylorus </li></ul><ul><li>Receives digestive enzymes and bile </li></ul><ul><li>Main pancreatic duct and common bile duct enter duodenum </li></ul><ul><ul><li>Sphincters control entry of bile and pancreatic juices </li></ul></ul>
    27. 27. The Duodenum and Related Organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
    28. 28. The Lower GI Tract
    29. 29. The Large Intestine <ul><li>The large intestine is comprised of: </li></ul><ul><ul><li>The colon— </li></ul></ul><ul><ul><ul><li>That portion distal to the ileum and proximal to the rectum </li></ul></ul></ul><ul><ul><ul><li>Approximately 150 cm (5 feet) in length </li></ul></ul></ul><ul><ul><ul><li>Larger diameter proximally </li></ul></ul></ul><ul><ul><li>The rectum— </li></ul></ul><ul><ul><ul><li>That portion distal to the colon and proximal to the anus </li></ul></ul></ul><ul><ul><ul><li>Approximately 12-15 cm (5-6 inches) in length </li></ul></ul></ul><ul><ul><li>The anal canal— </li></ul></ul><ul><ul><ul><li>That portion distal to the rectum, terminating at the anal verge </li></ul></ul></ul><ul><ul><ul><li>Approximately 4 cm (1 ½ inches) long </li></ul></ul></ul>
    30. 30. Characteristics of the Colon <ul><li>The colon has 3 unique characteristics: </li></ul><ul><ul><li>The haustra— </li></ul></ul><ul><ul><ul><li>A haustrum is a dilatation or sacculation of the colon. </li></ul></ul></ul><ul><ul><ul><li>These are multiple ( haustra is plural). </li></ul></ul></ul><ul><ul><li>The tenia coli— </li></ul></ul><ul><ul><ul><li>These are three longitudinal bands of thickened smooth muscle (muscularis externa) traversing the entire length. </li></ul></ul></ul><ul><ul><ul><li>All 3 originate jointly at the base of the vermiform appendix. </li></ul></ul></ul><ul><ul><ul><li>They gradually disappear at the rectosigmoid by diverging uniformly. </li></ul></ul></ul><ul><ul><li>The appendices epiploicae— </li></ul></ul><ul><ul><ul><li>These are small pouches of fat along the tenia coli . </li></ul></ul></ul>
    31. 31. The Large Intestine
    32. 32. Characteristics of the Colon Appendices Epiploicae Haustra Tenia Coli
    33. 33. Characteristics of the Rectum <ul><li>The rectum is an “S” shaped reservoir found in the pelvis. </li></ul><ul><li>Most of the rectum has only 3 tissue layers—mucosa, submucosa, and muscularis—since all but the upper anterior rectum is below the visceral peritoneal covering (extra- and infra-peritoneal) and, therefore, has no serosa. </li></ul><ul><li>The adipose tissue contained within the fascia propria posterior to the rectum is ( incorrectly) referred to as the mesorectum . </li></ul><ul><li>The tenia coli completely surround the rectum, having merged in the rectosigmoid from 3 distinct columns in the colon. </li></ul><ul><li>For surgical purposes, the rectum is divided into proximal, middle, and distal rectum. </li></ul><ul><li>The rectal curvatures result in inner mucosal infoldings, known as Valves of Houston , which can make traversing the rectum in retrograde fashion difficult during endoscopy or surgery. </li></ul>
    34. 34. Characteristics of the Rectum
    35. 35. Characteristics of the Rectum
    36. 36. Characteristics of the Anal Canal <ul><li>The anal canal begins at the level of the levator ani muscles. </li></ul><ul><li>The anal canal is surrounded by strong muscles and represents an anteroposterior slit due to their tonic contraction. </li></ul><ul><li>There are 2 “tubes” of muscle—inner is smooth, and outer is skeletal. </li></ul><ul><li>This short segment of GI tract is essential to fecal continence. </li></ul><ul><li>It is also prone to many diseases which can lead to major symptoms. </li></ul><ul><li>The midportion of the anal canal contains an undulating demarcation known as the dentate line . </li></ul><ul><li>The anal verge is the distal external-most portion of the GI tract. </li></ul>
    37. 37. Characteristics of the Anal Canal Anal Verge
    38. 38. Vasculature of Lower GI Tract
    39. 39. Vasculature of Lower GI Tract
    40. 40. Blood Supply to the Colon--SMA <ul><li>The Superior Mesenteric Artery (SMA): </li></ul><ul><ul><li>Supplies blood to the duodenum, pancreas, jejunum, ileum, and the right and transverse colon. </li></ul></ul><ul><ul><ul><li>The ileocolic artery provides blood supply to the ileocolic region, cecum and appendix. </li></ul></ul></ul><ul><ul><ul><li>The right colic artery provides blood supply to the ascending colon and the hepatic flexure. </li></ul></ul></ul><ul><ul><ul><li>The middle-colic (mid-colic) artery provides blood supply to the transverse colon and the hepatic and splenic flexures. </li></ul></ul></ul>
    41. 41. Blood Supply to the Colon--IMA <ul><li>The Inferior Mesenteric Artery (IMA) </li></ul><ul><ul><li>Supplies blood to the left colon, rectosigmoid and the superior 2/3 of the rectum. </li></ul></ul><ul><ul><li>The left colic artery supplies blood to the descending colon. </li></ul></ul><ul><ul><li>The sigmoidal arteries traverse the mesosigmoid and supply blood to the sigmoid colon. </li></ul></ul><ul><li>After supplying the sigmoidal arteries, the inferior mesenteric artery becomes the superior rectal artery . </li></ul><ul><li>This artery divides to left and right superior rectal arteries , and supplies the upper rectum. </li></ul>
    42. 42. Blood Supply to the Colon—The Marginal Artery <ul><li>The branches of the superior and inferior mesenteric arteries split and, with the exception of the rectal arteries, create a long artery that runs along the inner margin of the colon and is called the Marginal Artery of Drummond . </li></ul>
    43. 43. Blood Supply to the Colon—The Arc of Riolan <ul><li>The Arc of Riolan is present in a small number of people and is a secondary arcade which may help to provide collateral blood supply. </li></ul><ul><li>It is important to observe the high number of vascular arcades that are formed within the colon vasculature which allow for creative reconstructive intestinal surgery. </li></ul>Arc of Riolan
    44. 44. Blood Supply to the Rectum <ul><li>The superior 2/3 of the rectum is supplied by the left and right branches of the superior rectal artery (arising from the lower portion of the inferior mesenteric artery ). </li></ul>
    45. 45. Blood Supply to the Rectum <ul><li>The middle rectal arteries (when present) and inferior rectal arteries supply the lower portion of the rectum, the anal canal and the anal sphincter. </li></ul>The middle and inferior rectal arteries arise from the internal iliac arteries , which is important especially in cancer surgery as the proximal blood supply would have been divided . Due to inconsistencies in the blood supply to the lower rectum, it is often better to anastomose lower rather than higher as long as there is no tension.
    46. 46. Lymphatic Drainage of the Colon and Rectum <ul><li>The lymphatic system is a system of microscopic open-ended tubules and filter nodules whose function is to recuperate extravasated fluid and materials and redirect them to the cardiovascular system. </li></ul><ul><li>The lymphatic system also plays a roll in the absorption of fats in the digestive system. </li></ul><ul><li>It plays a crucial role in cancer as it allows for the passage of cancer cells from one organ to another through its system. </li></ul><ul><li>In the colon and rectum, the lymphatic system is linked closely with the vascular system. </li></ul><ul><li>Resection of major feeding arteries in cancer surgery will lead to resection of the regional lymph nodes, allowing for better staging of the tumors. </li></ul>
    47. 47. Lymphatic Drainage of the Colon and Rectum
    48. 48. Lymphatic Drainage in Cancer <ul><li>Plays crucial role in cancer as it allows for spread of cancer cells from one organ to another through the lymphatic system. </li></ul><ul><li>Colonic lymphatics follow arteries and veins. </li></ul><ul><li>Resection of vessels will result in resection of lymphatics in cancer surgery and allow for additional staging of a tumor. </li></ul>
    49. 49. Anatomy and Pathology <ul><li>With an understanding of normal anatomy, </li></ul><ul><li>We are in the position to understand Pathology. </li></ul>