SMALL INTESTINE LARGE INTESTINE RECTUM ABDOMINAL AORTA INFERIOR VENA CAVA THE ABDOMEN

Transcription

1 SMALL INTESTINE LARGE INTESTINE RECTUM ABDOMINAL AORTA INFERIOR VENA CAVA THE ABDOMEN

2 THE SMALL INTESTINE THE SMALL INTESTINE: Is the longest part of the gastrointesanal tract - length of 5 metres (3 7 metres) in the living adult Consists of the duodenum, jejunum, and ileum Extends from the pyloric opening to the ileocecal juncaon Is the locaaon of complete digesaon and absorpaon of most of the products of digesaon and water, electrolytes, and minerals such as calcium and iron

3 DUODENUM quick review THE SMALL INTESTINE

4 THE DUODENUM The duodenum pursues a C-shaped course around the head of the pancreas. It begins at the pylorus on the right side and ends at the duodenojejunal flexure (juncaon) on the lev side.

5 SUPERIOR (FIRST) PART OF THE DUODENUM: L1 level THE DUODENUM proximal 2 cm has a mesentery and is mobile, called the ampulla distal 3 cm (and the other three parts of the duodenum) have no mesentery and are immobile - they are retroperitoneal peritoneum covers anterior aspect it is bare of peritoneum posteriorly, except for the ampulla hepatoduodenal ligament (part of the lesser omentum) a[aches to the proximal part

6 DESCENDING (SECOND) PART: along the right sides of the L1 L3 vertebrae lies to the right of and parallel to the IVC THE DUODENUM the bile and main pancreaac ducts enter its posteromedial wall is enarely retroperitoneal anterior surface of its proximal and distal thirds is covered with peritoneum peritoneum reflects from its middle third to form the doublelayered mesentery of the transverse colon, the transverse mesocolon

7 THE DUODENUM INFERIOR (THIRD) PART: passing over the IVC, aorta, and L3 is crossed by the SMA posteriorly: right psoas major, IVC, aorta, and the right tesacular or ovarian vessels anterior surface is covered with peritoneum (except where it is crossed by the superior mesenteric vessels)

8 Ascending (fourth) part: runs superiorly from L3 L2 vertebra runs along the lev side of the aorta supported by the a[achment of a suspensory muscle of the duodenum (ligament of Treitz) anterior surface is covered with peritoneum THE DUODENUM

9 THE DUODENUM

10 THE JEJUNUM THE JEJUNUM

11 THE JEJUNUM The jejunum and ileum, 6 7m long, occupy the central and lower parts of the abdominal cavity and usually lie within the boundary formed by the abdominal colon. There is no clear disancaon between the two parts, but there is a gradual change in morphology from the proximal to distal ends of the small bowel. the jejunum begins at the duodenojejunal flexure the jejunum - proximal 2/5 the ileum distal 3/5 the ileum ends at the ileocecal juncnon

12 Most of the jejunum lies in the lev upper quadrant (LUQ) THE JEJUNUM Most of the ileum lies in the right lower quadrant (RLQ)

13 The mesentery a[aches the jejunum and ileum to the posterior abdominal wall - root of the mesentery (15cm long). THE JEJUNUM The root of the mesentery: directed obliquely inferiorly and to the right From the duodenojejunal juncnon on the lev side of vertebra L2 to the ileocolic juncnon and the right sacro-iliac joint.

14 The root of the mesentery crosses the: ascending and inferior parts of the duodenum, abdominal aorta, IVC, right ureter, right psoas major, right tesacular or ovarian vessels. THE JEJUNUM

15 Between the two layers of the mesentery are the: superior mesenteric vessels, lymph nodes, a variable amount of fat, autonomic nerves. THE JEJUNUM The SMA supplies the jejunum and ileum via jejunal and ileal arteries The SMA usually arises from the abdominal aorta at the level of the L1 vertebra - 1cm inferior celiac trunk. The SMA runs between the layers of the mesentery, sending branches to the jejunum and ileum

16 THE JEJUNUM The arteries unite to form loops or arches, called arterial arcades, which give rise to straight arteries, called vasa recta The SMV drains the jejunum and ileum. The SMV ends posterior to the neck of the pancreas, where it unites with the splenic vein to form the hepanc portal vein Specialized lymphaac vessels in the intesnnal villi that absorb fat are called lacteals.

17 THE JEJUNUM Within the mesentery, the lymph passes sequenaally through three groups of lymph nodes: juxta-intesnnal lymph nodes: located close to the intesanal wall. mesenteric lymph nodes: sca[ered among the arterial arcades. superior central nodes: located along the proximal part of the SMA. Efferent lymphaac vessels from the mesenteric lymph nodes drain to the superior mesenteric lymph nodes. LymphaAc vessels from the terminal ileum follow the ileal branch of the ileocolic artery to the ileocolic lymph nodes.

18 The innervanon of the small intesnne is by the enteric nervous system, which in the small intesane consists of the: submucosal plexus of Meissner and myenteric plexus of Auerbach. THE JEJUNUM

19 SYMPATHETIC Preganglionic neuronal cell bodies are located in the intermediolateral cell column of the spinal cord (T8 12). THE JEJUNUM Preganglionic axons form the: greater splanchnic nerve, lesser splanchnic nerve, least splanchnic nerve. SYMPATHETIC Postganglionic neuronal cell bodies are located in the celiac ganglion and superior mesenteric ganglion.

20 THE JEJUNUM PARASYMPATHETIC Preganglionic neuronal cell bodies are located in the dorsal nucleus of the vagus. Preganglionic axons run in CN X and reach the small intesane via the posterior vagal trunk. Postganglionic neuronal cell bodies are located in the enteric nervous system; some of these are the tradiaonal postganglionic parasympatheac neurons that release ACh as a neurotransmi[er. The postganglionic axons terminate on mucosal glands and smooth muscle.

21 THE JEJUNUM SympatheNc samulaaon reduces peristalac and secretory acavity of the intesane and acts as a vasoconstrictor, reducing or stopping digesaon and making blood (and energy) available for fleeing or fighang. ParasympatheNc samulaaon increases peristalac and secretory acavity of the intesane, restoring the digesaon process following a sympatheac reacaon.

22 THE JEJUNUM The small intesane also has sensory (visceral afferent) fibers. The intesane is insensiave to most pain samuli, including cuing and burning; however, it is sensiave to distension that is perceived as colic ( intesanal cramps ).

23 SMALL INTESTINE LARGE INTESTINE RECTUM ABDOMINAL AORTA INFERIOR VENA CAVA THE ABDOMEN

24 The large intesnne consists of the: cecum appendix ascending transverse descending sigmoid colon rectum anal canal THE LARGE INTESTINE

25 THE LARGE INTESTINE Extends from the ileocecal juncnon to the anus and is approximately 1.5 m (5 V) long. FuncAons to convert the liquid contents of the ileum into semisolid feces by absorbing water, salts, and electrolytes.

26 THE LARGE INTESTINE The large intesnne can be disanguished from the small intesane by: Omental appendices: small, fa[y, omentum-like projecaons. Teniae coli: three disanct longitudinal bands: 1.mesocolic tenia, to which the transverse and sigmoid mesocolons a[ach; 2. omental tenia, to which the omental appendices a[ach; and 3. free tenia, to which neither mesocolons nor omental appendices are a[ached. Haustra: sacculaaons of the wall of the colon between the teniae A much greater caliber (internal diameter).

27 THE LARGE INTESTINE The teniae coli, thickened bands of smooth muscle represenang most of the longitudinal coat, begin at the base of the appendix as the thick longitudinal layer of the appendix separates into three bands. The cecum is the first part of the large intesane and is a blind intesanal pouch. It lies in the iliac fossa of the right lower quadrant of the abdomen It may be displaced from the iliac fossa, but it is commonly bound to the lateral abdominal wall by one or more cecal folds of peritoneum

28 THE LARGE INTESTINE The ileal orifice enters the cecum between ileocolic lips (superior and inferior), folds that meet laterally forming ridges called the frenula of the ileal orifice. The appendix is a blind intesanal diveraculum (6 10cm in length) that contains masses of lymphoid Assue. The appendix has a short TRIANGULAR mesentery, the meso-appendix The posiaon of the appendix is variable, but it is usually retrocecal

29 THE LARGE INTESTINE The arterial supply of the cecum is from the ileocolic artery, the terminal branch of the SMA. The appendicular artery, a branch of the ileocolic artery, supplies the appendix. Venous drainage from the cecum and appendix flow through a tributary of the SMV, the ileocolic vein.

30 THE LARGE INTESTINE LymphaNc drainage of the cecum and appendix passes to lymph nodes in the meso-appendix and to the ileocolic lymph nodes that lie along the ileocolic artery. The nerve supply to the cecum and appendix derives from the sympatheac and parasympatheac nerves from the superior mesenteric plexus.

31 The colon has 4 parts: ascending transverse descending and sigmoid. THE LARGE INTESTINE The ascending colon passes superiorly on the right side of the abdominal cavity from the cecum to the right lobe of the liver, where it turns to the lev at the right colic flexure - hepaac flexure.

32 THE LARGE INTESTINE The arterial supply to the ascending colon and right colic flexure is from branches of the SMA, the ileocolic and right colic arteries. Venous drainage from the ascending colon flows through tributaries of the SMV, the ileocolic and right colic veins.

33 THE LARGE INTESTINE The transverse colon is the third, longest, and most mobile part of the large intesane. From the right colic flexure to the lev colic flexure. The descending colon is between the lev colic flexure and the lev iliac fossa, where it is conanuous with the sigmoid colon.

34 The le_ colic flexure (splenic flexure) is usually: more superior, more acute, less mobile. THE LARGE INTESTINE The mesentery of the transverse colon (transverse mesocolon) is adherent to or fused with the posterior wall of the omental bursa. The root of the transverse mesocolon lies along the inferior border of the pancreas and is conanuous with the parietal peritoneum posteriorly.

35 THE LARGE INTESTINE In tall thin people, the transverse colon may extend into the pelvis The arterial supply of the transverse colon is mainly from the middle colic artery, a branch of the SMA. The arterial supply of the transverse colon is mainly from the middle colic artery, a branch of the SMA. The transverse colon may also receive arterial blood from the right and lev colic arteries via anastomoses.

36 Venous drainage of the transverse colon is through the SMV. THE LARGE INTESTINE The lymphanc drainage of the transverse colon is to the middle colic lymph nodes, which in turn drain to the superior mesenteric lymph nodes.

37 The peritoneum covers the descending colon anteriorly and laterally. THE LARGE INTESTINE The arterial supply of the descending is from the le_ colic, branches of the IMA. Venous drainage from the descending colon is provided by the IMV, flowing usually into the splenic vein and then the hepaac portal vein on its way to the liver.

38 The sigmoid colon, characterized by its S-shaped loop of variable length, links the descending colon and the rectum. THE LARGE INTESTINE The sigmoid colon has a long mesentery, the sigmoid mesocolon, and therefore has considerable freedom of movement The omental appendices of the sigmoid colon are long. The arterial supply of the sigmoid colon is from the sigmoid arteries, branches of the IMA.

39 THE LARGE INTESTINE The SMA supplying blood to the lev colic flexure - derived from the embryonic midgut. The IMA supplying blood from the lev colic flexure - derived from the embryonic hindgut. Venous drainage from the sigmoid colon is provided by the IMV, flowing usually into the splenic vein and then the hepaac portal vein on its way to the liver. LymphaNc drainage from the descending colon and sigmoid colon is conducted through vessels passing to the epicolic and paracolic nodes, and then through the intermediate colic lymph nodes along the lev colic artery.

40 THE LARGE INTESTINE The sympathenc nerve supply of the descending and sigmoid colon is from the lumbar part of the sympathenc trunk via lumbar (abdominopelvic) splanchnic nerves. The parasympathenc nerve supply is from the pelvic splanchnic nerves via the inferior hypogastric (pelvic) plexus and nerves (S2-S4).

41 SMALL INTESTINE LARGE INTESTINE RECTUM ABDOMINAL AORTA INFERIOR VENA CAVA THE ABDOMEN

42 THE RECTUM The rectum is the fixed (primarily retroperitoneal and subperitoneal) terminal part of the large intesane. The rectum is conanuous with the sigmoid colon at the level of S3 vertebra, is conanuous inferiorly with the anal canal.

43 SMALL INTESTINE LARGE INTESTINE RECTUM ABDOMINAL AORTA INFERIOR VENA CAVA THE ABDOMEN

44 The abdominal aorta begins at the aornc hiatus in the diaphragm at the level of the T12 vertebra and ends at the level of the L4 vertebra by dividing into the right and le_ common iliac arteries. THE ABDOMINAL AORTA The branches of the aorta are described as: anterior, lateral and dorsal. The abdominal aorta is approximately 13 cm in length.

45 THE ABDOMINAL AORTA The anterior and lateral branches are distributed to the viscera. The dorsal branches supply the body wall, vertebral column, vertebral canal and its contents. The aorta terminates by dividing into the right and le_ common iliac arteries.

46 THE ABDOMINAL AORTA The branches of the aorta: inferior phrenic a. celiac trunk superior mesenteric a. middle suprarenal a. renal a. tesacular or ovarian a. four lumbar aa. inferior mesenteric a. median sacral a. common iliac a.

47 THE ABDOMINAL AORTA THE BRANCHES OF THE AORTA INFERIOR PHRENIC A. Paired arteries that supply the diaphragm, which they enter from below. It supplies diaphragm and gives superior suprarenal arteries. CELIAC TRUNK Common stem of the lev gastric, common hepaac and splenic arteries at the level of T12. Anterior to the celiac trunk lies the lesser sac. The celiac plexus surrounds the trunk, sending extensions along its branches. The body of the pancreas and the splenic vein are inferior to the celiac trunk.

48 THE ABDOMINAL AORTA THE BRANCHES OF THE AORTA SUPERIOR MESENTERIC ARTERY Unpaired branch of the aorta arising about 1 cm below the celiac trunk. It extends from behind the pancreas to the uncinate process and passes with its branches into the mesentery and mesocolon. MIDDLE SUPRARENAL ARTERY Arises from the lateral aspect of the abdominal aorta, level with the superior mesenteric artery and supplies the suprarenal gland. RENAL ARTERY The largest branches of the abdominal aorta, it arises from the aorta in front of L1 and divides into several branches which enter the kidney.

49 THE ABDOMINAL AORTA THE BRANCHES OF THE AORTA RENAL ARTERY The right is longer and usually arises slightly higher than the lev. It passes posterior to the inferior vena cava, right renal vein, head of the pancreas and second part of the duodenum. TESTICULAR OR OVARIAN ARTERY The gonadal arteries are two long vessels, that arise from the aorta inferior to the renal arteries. Each passes inferolaterally under the parietal peritoneum on psoas major. FOUR LUMBAR ARTERIES They arise from the posterolateral aspect of the aorta, which correspond to the intercostal arteries.

50 THE ABDOMINAL AORTA THE BRANCHES OF THE AORTA INFERIOR MESENTERIC ARTERY It arises from the anterior or lev anterolateral aspect of the aorta. The inferior mesenteric artery is usually smaller in calibre than the superior mesenteric artery. MEDIAN SACRAL ARTERY Arises from the posterior aspect of the aorta a li[le above its bifurcaaon. It descends in the midline and ends in the coccygeal body. COMMON ILIAC ARTERY It extends from the bifurcaaon of the descending aorta at L4/L5 to its division into the internal and external iliac arteries in front of the sacroiliac joint.

51 THE ABDOMINAL AORTA The branches of the aorta: inferior phrenic a. celiac trunk superior mesenteric a. middle suprarenal a. renal a. tesacular or ovarian a. four lumbar aa. inferior mesenteric a. median sacral a. common iliac a.

52 THE ABDOMINAL AORTA The common iliac arteries diverge and run inferolaterally, following the medial border of the psoas muscles to the pelvic brim. The internal iliac artery enters the pelvis. The external iliac artery follows the iliopsoas muscle, gives rise to the inferior epigastric and deep circumflex iliac arteries RELATIONS OF ABDOMINAL AORTA: Celiac plexus and ganglion Body of the pancreas and splenic vein LeV renal vein Horizontal part of the duodenum Coils of small intesane

53 THE ABDOMINAL AORTA RELATIONS OF ABDOMINAL AORTA: On the right, the aorta is related to the azygos vein, cisterna chyi, thoracic duct, right crus of the diaphragm, and right celiac ganglion. On the le_, the aorta is related to the lev crus of the diaphragm and the lev celiac ganglion.

54 SMALL INTESTINE LARGE INTESTINE RECTUM ABDOMINAL AORTA INFERIOR VENA CAVA THE ABDOMEN

55 THE THE INFERIOR VENA CAVA The IVC leaves the abdomen by passing through the caval opening in the diaphragm and enters the thorax at the T8 vertebral level. The inferior vena cava (IVC) begins anterior to the L5 vertebra by the union of the common iliac veins.

56 THE INFERIOR VENA CAVA THE THE INFERIOR VENA CAVA The inferior vena cava is formed by the juncaon of the common iliac veins anterior to the fivh lumbar vertebral body, a li[le to its right. It ascends anterior to the vertebral column, to the right of the aorta, and is contained in a deep groove on the posterior surface of the liver. The abdominal poraon of the inferior vena cava is devoid of valves.

57 TRIBUTARIES the common iliac veins at its origin lumbar, right gonadal, renal, right suprarenal, inferior phrenic, hepaac veins THE THE INFERIOR VENA CAVA

58 THE THE INFERIOR VENA CAVA THE INFERIOR VENA CAVA The veins of the posterior abdominal wall are tributaries of the IVC, except for the le_ tesncular or ovarian vein, which enters the lev renal vein instead of entering the IVC The IVC returns blood from the: lower limbs, most of the back, abdominal walls, abdominopelvic viscera.

59 THE THE INFERIOR VENA CAVA Blood from the abdominal viscera passes through the portal venous system and the liver before entering the IVC via the hepanc veins. The IVC collects blood from the lower limbs and non-portal blood from the abdomen and pelvis. The tributaries of the IVC correspond to the paired visceral and parietal branches of the abdominal aorta. All the blood from the gastrointesnnal tract is collected by the hepaac portal system and passes through the hepaac veins to the IVC. The veins that correspond to the unpaired visceral branches of the aorta are instead tributaries of the hepa9c portal vein.

60 THE THE INFERIOR VENA CAVA The branches corresponding to the paired visceral branches of the abdominal aorta include the: right suprarenal vein, right and lev renal veins, right gonadal (tesacular or ovarian) vein. The le: suprarenal and gonadal veins drain indirectly into the IVC because they are tributaries of the le: renal vein.

61 INTRAPERITONEAL AND RETROPERITONEAL ORGANS

62 INTRAPERITONEAL AND RETROPERITONEAL ORGANS: THE PERITONEAL CAVITY Intraperitoneal organs are suspended by a mesentery and are almost completely enclosed in visceral peritoneum. These organs are mobile. Retroperitoneal organs are paraally covered on one side with parietal peritoneum and are immobile or fixed organs. Many retroperitoneal organs were originally suspended by a mesentery and become secondarily retroperitoneal.

63 INTRAPERITONEAL AND RETROPERITONEAL ORGANS: Major lntraperitoneal Organs (suspended by a mesentery) Stomach Liver and gallbladder Spleen Duodenum, 1st part Tail of pancreas Jejunum Ileum Appendix Transverse colon Sigmoid colon THE PERITONEAL CAVITY

64 INTRAPERITONEAL AND RETROPERITONEAL ORGANS: THE PERITONEAL CAVITY Major Secondary Retroperitoneal Organs (lost a mesentery during development) Duodenum, 2 nd and 3 rd parts Head, neck, and body of pancreas Ascending colon Descending colon Upper rectum

65 INTRAPERITONEAL AND RETROPERITONEAL ORGANS: THE PERITONEAL CAVITY Major Primary Retroperitoneal Organs (never had a mesentery) Kidneys Adrenal glands Ureters Aorta lnferior vena cava Lower rectum Anal canal

66 ADULT STRUCTURES DERIVED FROM EACH OF THE 3 DIVISIONS OF THE PRIMITIVE GUT TUBE THE PERITONEAL CAVITY FOREGUT Artery: celiac ParasympatheNc innervanon: vagus nerves SympatheNc innervanon: preganglionics: thoracic splanchnic nerves, T5-T9 postganglionic cell bodies: celiac ganglion Referred Pain: Epigastrium Foregut DerivaNves: Esophagus Stomach Duodenum (first and second parts) Liver Pancreas Biliary apparatus Gallbladder

67 ADULT STRUCTURES DERIVED FROM EACH OF THE 3 DIVISIONS OF THE PRIMITIVE GUT TUBE THE PERITONEAL CAVITY MIDGUT Artery: superior mesenteric ParasympatheNc innervanon: vagus nerves SympatheNc innervanon: - Preganglionics: thoracic splanchnic nerves, T9-T12 - Postganglionic cell bodies: superior mesenteric ganglion Referred Pain: Umbilical Midgut DerivaNves Duodenum (second, third, and fourth parts) Jejunum Ileum Cecum Appendix Ascending colon Transverse colon (proximal two-thirds)

68 ADULT STRUCTURES DERIVED FROM EACH OF THE 3 DIVISIONS OF THE PRIMITIVE GUT TUBE THE PERITONEAL CAVITY HINDGUT Artery: inferior mesenteric ParasympatheNc innervanon: pelvic splanchnic nerves SympatheNc innervanon: preganglionics: lumbar splanchnic nerves, L1-L2 postganglionic cell bodies: inferior mesenteric ganglion Referred Pain: Hypogastrium Hindgut DerivaNves Transverse colon (distal thirdsplenic flexure) Descending colon Sigmoid colon Rectum Anal canal (above pecanate line)