Digestive System - Stomach (PDF)

Stomach (gaster)  The stomach is a musculoglandular sac of digestive tube. Classification of stomach: A- According to number of compartments : 1-Monolocular st.: have one compartment as in dog, pig and horse. 2-Multilocular st.: have more than one compartments as in ru...

Stomach (gaster)  The stomach is a musculoglandular sac of digestive tube. Classification of stomach: A- According to number of compartments : 1-Monolocular st.: have one compartment as in dog, pig and horse. 2-Multilocular st.: have more than one compartments as in ruminants (4 chambers). B- According to type of mucous membrane : 1-Simple st.: lined wholly with glandular mucous membrane as in dog. 2-Compound (composite) st.: the mucous membrane is partly glandular and partly nonglandular as in pig, horse and ruminants. The nonglandular part or parts called esophageal or proventricular part. Anatomical features:  The stomach presents two orifices, two borders and two surfaces. A-The openings are: 1-Cardiac orifice (cardia): where esophagus opens in stomach. It lies to the left of median plane.  Pyloric orifice (pylorus): where stomach connects duodenum and is marked externally by pyloric constriction. The pyloric orifice lies to right of median plane in contact with visceral surface of liver. B- The borders are: 1-Dorsal border: concave, extends between cardia and pylorus, known as lesser curvature. In some species it forms deep notch known angular notch. 2-Ventral border: much larger, extends also from cardia passing with fundus then crossing median plane till pylorus, is known as greater curvature. C-The surfaces are: 1-Parietal or diaphragmatic surface: is directed craniodorsally and to the left, related to diaphragm and ventrally to left lobe of liver. 2-Visceral or intestinal surface: is directed caudoventrally and to the right, related to intestine, pancreas and the greater omentum.  Parts of stomach:  The part of stomach lies to left of angular notch called the body.  The part of body bulges above level of cardia called fundus and is separated from cardia by cardiac notch.  Right to the body is the pyloric region which is divided into wide pyloric antrum and narrow pyloric canal which ends at pyloric sphincter. Fixation of stomach: a) Non peritoneal fixation: 1) Attachment to esophagus and duodenum. 2) Pressures of adjacent organs. b) Peritoneal fixation: Through omenta and ligaments:- 1. Greater omentum: attaches greater curvature of stomach to intestinal segments. 2. Gastrosplenic ligament: attaches stomach to spleen. 3. Gastrosphrenic ligament: attaches stomach to diaphragm 4. Lesser omentum: attaches lesser curvature of stomach and cranial part of duodenum to liver. Structure of stomach: The wall of the stomach consists of; mucous membrane, muscular and serous coats. 1- Mucous coat: – The mucosa differs according to type of the stomach. In glandular st. it is wholly formed of simple columnar epithelium with some goblet cells. While in nonglandular part st. it is formed of stratified squamous cornified epithelium. – The glandular mucosa is divided ;based on the type of glands, into three regions which are cardiac, fundic and pyloric. The glands open into gastric pits. 2- Muscular coat: - It consists of 3 layers of smooth muscle fibers, outer longitudinal, middle circular and inner oblique. - The outer layer comes from esophagus and forms two longitudinal bands along each curvature and can be reached to about pylorus. - The middle layer presents only in body and pyloric part. it is thick at pylorus to form pyloric sphincter. - The internal layer presents only in fundus and body. It is thick at cardia to form cardiac sphincter. 3- Serous coat: - The serous layer covers the greater part of the stomach and continues with greater and lesser omentum.  Stomach DOG PIG HORSE Type Monolocular Monolocular Monolocular Simple Compound Compound Position Intra thoracic part Intra thoracic Intra thoracic part 1-Empty of abd. cavity. part of abd. of abd. cavity. Separated from cavity. Not reach abd. abd. floor by liver Not reach abd. floor and intestine. floor 2-Moderate Reach abd. floor Not reach abd. Not reach abd. full floor floor 3-Complete Reach abd. Floor Reach abd. Separated from full floor abd. Floor by colon , cecal apex.  Empty st. Sac shape , J- shape, cardia U-shape. bears large and pylorus Full st. sac like blind close each other. enlargement. divericulum. Greater cur. 4 Ventricular Has large blind Shape times as lesser diverticulum sac pluging from cur. marked by fundus, termed circular saccus cecus groove. Dorsal part of Very short lesser lesser cur. Is -------- cur. straight Pyloric Absent Dorsal rounded Absent prominence from torus pyloric sphincter. Angular Deep Absent Deep ,because stmach strongly notch bent.  Internal Elongated area Lines saccus No at cardia ceacus, separated character from gl. Part by 1-Proventricular margo plicatus. part Narrow annular About 1/3 of gl. Narrow line along 2-Cardiac gl. zone, surround mucosa, reach margo plicatus. Not region cardia lesser curv. reach les. curv. 3-Fundic gl. About 2/3 of gl. About 1/3 of gl. Lines most of body, Region mucosa, has mucosa, not not reach lesser transitional reach lesser curv. folds curv. Distal 1/3 of gl. About 1/3 of gl. lines pyloric region 4-Pyloric gl. mucosa. mucosa., has & part of lesser cur. region irregular folds fold separates Margo plicatus No No nonglandular part from glandular  Ruminant Stomach It consists of 4 chambers: rumen, reticulum and omasum, are forestomach (proventriculus) , lined with nonglandular mucosa.The fourth chamber; abomasum, lined with glandular mucosa. Relative position: The rumen lies on left side, reticulum cranially and omasum on the right. The abomasum lies ventrally. Capacity of stomach: - In ox is110-235 liters. The rumen holds about 80%, reticulum 5%, omasum 7% and abomasum 8% of the total capacity. - In small ruminants the capacity of the stomach is16- 30 liters.  The rumen Position :  It occupies left half of abdominal cavity, extending from diaphragm to pelvic inlet. Anatomical description:  It has two surfaces and two curvatures:  Parietal (left) surface: related to diaphragm, spleen and left bdominal wall. Direct contact of rumen with left flank facilitates auscultation, palpation ,trocherization and surgical operation.  Visceral (right) surface: related to intestine, liver, omasum and abomasum.  Both parietal & visceral surfaces characterized by ruminal grooves.   Dorsal curvature: lies against diaphragm and roof of abdominal cavity.  Ventral curvature: lies against abdominal floor. Ruminal grooves  Rumen is divided externally into several parts by a number of ruminal grooves which are arranged as follow:  right and left longitudinal grooves: on the visceral and parietal surfaces respectively.  Right accessory groove: extends from right long. groove ,describes a curve dorsally and rejoins right long. groove enclosing insula ruminis.  left accessory groove: is small extends dorsally from left long. groove.  Cranialand caudal transverse grooves which unite with right & left long. grooves.  Right & left dorsal and ventral coronary grooves: extend from caudal end of right and left longitudanal grooves and demarcate the caudoventral & caudodorsal blind sacs. Ventral coronary grooves reach ventral curvature of rumen, while dorsal grooves don't reach its dorsal curvature.  Ruminoreticular groove: separates rumen (ruminal atrium) from reticulum ventrally.  Parts of rumen : 1-Dorsal and ventral ruminal sacs: result from union of longitudinal and transverse grooves. 2-Ruminal atrium and ruminal recess: represent cranial parts of the dorsal and ventral ruminal sacs respectively 3-Caudodorsal & caudoventral blind sacs: represent caudal parts of the dorsal & ventral ruminal sacs respectively. = Esophagus enters stomach at cardia which lies at the junction of rumen and reticulum. Interior of rumen:  Ruminal pillars: -With exception of ruminoreticular groove, all grooves are represented by muscular pillars which project into the cavity of rumen. -Cranial pillar projects between ruminal atrium and recess, but caudal pillar projects between the two blind sacs.  Ruminal papillae: -The mucosa forms large conical or tongue shaped ruminal papillae. They are well developed in ventral sac, blind sacs, and in ruminal atrium, but decrease in size toward pillars on which they are absent. Most roof lacks papillae. -The papillae increase surface area of mucosa through which fatty acids and sodium are absorbed.  The reticulum Position:  It is the most cranial chamber, spherical in shape. It lies in intrathoracic part of abdominal cavity between diaphragm and rumen.  Dorsally, it is continued with ruminal atrium. But ventrally it is separated from rumen by ruminoreticular groove.  It is involved in traumatic reticulitis which may lead to reticulopericarditis. Anatomical description:  It has two surfaces; A- diaphragmatic S.: convex, related to diaphragm B- visceral S.: related to rumen.  It is related: -on right side: to liver, omasum and abomasum. -on left side: to costal part of diaphragm. -ventrally: to sternal part of diaphragm and xiphoid cartilage. -cranially: to diaphragm. -caudally: to rumen. Interior of reticulum:- - It has well developed muscular wall. - The mucosa forms permanent crests of about 1 cm high, which intersect to form honeycomb like cells. Each cell is subdivided by lower secondary crests. The crests and the cells are studded with small papillae.  The omasum Position: - It lies ventrally in intrathoracic part of abdominal cavity to the right of median plane, between rumen and right abdominal wall. Anatomical description: - It is spherical in shape and larger than reticulum in ox. - It has two curvatures; two surfaces and short neck. Greater curvature: faces dorsocaudally and to right, lesser curvature: faces in opposite direction. Visceral (left) surface: related to rumen.  Parietal (right) surface: related to diaphragm and liver, below the latter a small area lies against right abdominal wall. Ventrally: it related to reticulum and abomasum. Caudally: to the jejunum. Neck: is very short narrow part connects omasum and reticulum. - Omasum of small rum. is oval and smaller than reticulum. It does not in contact with right abdominal wall. Interior of omasum: - It communicates with reticulum through reticuloomasal opening and with abomasum through omasoabomasal opening. - The inner wall forms different sized parallel folds termed omasal laminae. Their surfaces covered with horny papillae. They are separated by interlaminar recesses. The laminae are arranged as; 1,4.3,4,2,4.3,4,1 etc. (1= highest; 4= lowest fold).  The abomasum Position: - The abomasum or true stomach is the most distal compartment in form of an elongated sac. It lies chiefly on abdominal floor. The fundus lies on abdominal floor in left side, the pyloric part on right side and the body crosses median plane from left to right. - The abomasum is closely related to the ruminal recess. Anatomical description: - The abomasum like simple stomach is divided into fundus, body and pyloric parts. - The abomasum has: = two curvatures: greater faces ventrally and attaches with greater omentum; and lesser faces dorsally and attaches with lesser omentum. = two surfaces: parietal ( related mainly to abdominal floor) and visceral ( related to rumen and omasum). Interior of abomasum: - It has glandular mucosa which presents cardiac, fundic, and pyloric regions. 1-The cardiac region: is narrow area surrounding omasoabomasal opening. 2-The fundic region: includes most of fundus and body, it contains permanent spiral folds which absent at lesser curvature 3-The pyloric region: includes pyloric part. - The pyloric sphincter is not well developed and presents large torus pyloricus which is round protuberance inside lesser curvature.  The gastric groove - The gastric groove of ruminant stomach is well developed and of considerable physiological importance. - It extends from cardia through reticulum, omasum, and abomasum to pylorus. it is divided into three segments; reticular, omasal, and abomasal grooves. Function:- - Through gastric groove swallowed milk in suckling animals is conducted through reticular and omasal grooves directly into abomasum. Parts of gastric groove: 1-Reticular groove: extends from cardia to reticuloomasal opening. It is formed of two muscular spiral ridges. 2-Omasal groove: extends from reticuloomasal opening to omasoabomasal opening. It is bounded by two mucosal ridges. 3-Abomasal groove: extends from omasoabomasal opening to pylorus. It is represented by band like area extends along lesser curvature of abomasum which is free from spiral folds.  Intestine  It extends from stomach to anus. It consists of small and large intestine. The small intestine includes duodenum, jejunum and ileum, It can be divided into fixed part (duodenum) and mesenteric part (jejunum and ileum).The large intestine consists of the cecum, colon, rectum and anal canal.  Canines have shortest intestine followed by equines, pig and ruminants.  The duodenum  It extends from pylorus to duodenojejunal flexure. It consists of three parts, three flexures and three ligaments. Parts and course: -Three parts are: cranial part, descending duodenum and ascending duodenum. -Three flexures are :cranial, caudal, and duodenojejunal. = Cranial part:passes to the right on the liver forming cranial flexure, which continues as descending duodenum. =Des. Duodenum: runs caudally on right side in relation to ascending colon. It forms caudal flexure behind right kidney base ef cecum) then it turns to left and cranially to continue as ascending duodenum. =Asc.Duodenoum: runs cranially on left side in relation to descending colon, to join jejunum at duodenojejunal flexure. ** Cranial part forms sigmoid loop in horse, ruminants and pig. It presents major and minor duodenal papillae at which pancreatic ducts with bile duct open. Fixation of duodenum: 1- Mesoduodenum : short fold except dog has relatively wide one. 2-Hepatoduodenal ligament: attaches cranial part of duodenum to liver. 3-Duodenocolic ligament: attaches Asc. duodenum to des. colon The jejunum It is the longest part of small intestine, begins at duodenojejunal flexure. Mesentery: - It is a wide fan-shaped peritoneal fold. - it is long and allows jejunum great range, especially in dog and horse. Position : It varies according to species:  In ruminants and pig: long jejunum found mainly on right half of abdominal cavity, surrounding coiled ascending colon.  In dog: jejunal loops occupy abdominal floor and covered by greater omentum.  In horse: because of great length of the mesentery, jejunal loops are not confined to particular area but found mostly in left dorsal quadrate.  As a result of mobility of jejunal coils in equines, intestinal colic may develop.  The ileum - It is short terminal part of small intestine. - It is suspended by mesoileum and is attached to cecum by ileocecal ligament. - It terminates at ileocecal openings which is provided by ileal sphincter.  The cecum - It varies in size, shape and position in different species. Vermiform appendix of cecum of man is absent in domestic animals but presents in rabbit. Size: depends on species; it is shortest in cat and increasingly longer in dog, pig, ruminants and horse. Position: it lies on right side of abdominal cavity in all animals except in pig on left side. Communcation: in all animals ileum joins cecum at ileocecal orifice. In addition only in horse cecum joins colon at cecocolic orifice, but in other animals it continues with colon without definite line of demarcation. Muscular bands: present only in pig and horse. Fixation: 1-Mesocecum: between cecum and dorsal abd.wall. 2-Ileocecal ligament: between cecum and ileum. 3- Cecocolic ligament: between cecum and ascending colon (in horse). Cecum in horse:-  It has remarkable size and position.  It occupies large part of right half of abdominal cavity, from pelvic inlet to intrathoracic part of abd. cavity.  It consists of base, body and apex.  The base: most dorsal part lies in right flank region. It has dorsal greater and ventral lesser curvatures. Both ileocecal and cecocolic orifices open on lesser curvature.  The body: extends cranioventrally to lie between right and left ventral colon on abdominal floor.  The apex: narrowest cranial end, lies in xiphoid region of abdominal cavity.  The body has four bands; dorsal, ventral, lateral and medial. The dorsal band is attached to ileocecal ligament and lateral one to cecocolic ligament. They bands make four rows of sacculations. cecum Dog Pig Rum. Horse Camel Position on right on left side on right occupies on right side of of abd. side of abd. large part of side of abd. abd. cavity. cavity. cavity. cavity. right half of abd. cavity , from pelvic inlet to intrath. part Of abd. cavity. Shape Irregularl Cylindrical Cylindrical Comma C-shaped, y twisted shape convexity ( screw- like ) directed dorsally. Length 8-30 cm 30-40 cm. In ox → It has 50-70 cm. 50-70 cm remarkable In S. Rum→ size (about 25-42 cm 125cm). Muscular No -3 bands; No -4 bands No bands muscular ventral, muscular ;dorsal, muscular bands bands lateral and bands ventral, medial. medial and - 3 rows of lateral. sacculations - 4 rows of sacculations openings -Ileocecal -Ileocecal -Ileocecal -Ileocecal -Ileocecal orifice. orifice. orifice. orifice. orifice. -continues -continues directly w - continues - continues -Cecocolic colon directly w directly orifice. directly w without colon colon with colon without line of without line without demarcatio line of n. of line of demarcati demarcation demarcatio on. n. Ligaments -Ileocecal -Ileocecal -Ileocecal -Ileocecal -Ileocecal ligament ligament ligament ligament ligament -Cecocolic ligament  The colon The colon is divided into ascending, transverse and descending colon.  The ascending colon lies mainly the in right side, the transverse colon crosses the median plane from right to left side it then descends on the left side as descending colon  Ascending colon of dog:  The simplest arrangement of colon presents in dog as in man.  It passes cranially on right side, crosses median plane infront to cranial mesenteric artery as transverse colon; it then passes caudally on left side as descending colon. Ascending colon of pig:  It forms a spiral loop which consists of three double spiral coils forming a cone or turban like structure.  These coils are formed of centripetal and centrifugal coils which are continuous at central flexure.  Centripetal coils has two bands which absent on centrifugal ones,centripetal coils have larger diameter than centrifugal coils. Ascending colon of ruminants:  It consists of three loops, proximal, spiral and distal.  Proximal loop: “S” shape, consists of three parts; ventral, middle and dorsal. The ventral one is directed cranially , the middle part caudally and the dorsal part continues cranially by spiral loop.  Spiral loop: consists of two coils; centripetal and centrifugal, which form intestinal disc. Both coils unite at central flexure.  Distal loop: consists of two parts; dorsal and ventral. The dorsal one is directed caudally and the ventral one cranially and continued with transverse colon. Ascending (great) colon of horse:  It occupies the floor of the abdomen.  It is formed of double U-shaped loops.  It consists of 4 parts and 3 flexures: right ventral colon, ventral diaphragmatic flexure, left ventral colon, pelvic flexure, left dorsal colon, dorsal diaphragmatic flexure and right dorsal colon.  The ventral colon lies on abdominal floor. The ventral and dorsal colons are continuous at pelivic flexure. They are attached with each other by intercolic ligament.  The ventral diaphragmatic flexure lies dorsal to xiphoid cartilage.  The ventral parts of ascending colon have 4 bands. The left dorsal colon and pelvic flexure have 1 band, while right dorsal colon and dorsal diaphragmatic flexure have 3 bands.  The diameter varies at different parts. The widest part is right dorsal colon , followed by right and left ventral colon. The pelvic flexure and the beginning of left dorsal colon have the narrowest diameter.  Fixation of ascending colon by: 1-Mesocolon. 2-Intercolic lig. 3-Cecocolic lig.  Transverse colon - It begins from ascending colon at right side, then passes to left side cranial to cranial mesenteric artery to continue as descending colon. - It has no bands or sacculations. Descending (small) colon  It lies in the left dorsal quadrant of body cavity. It passes caudally under the dorsal abdominal wall with which it is attached by mesocolon and attached to ascending duodenum by duodenocolic ligament. It enters pelvic cavity to continue as rectum. - In ruminants, it presents sigmoid colon. - In horse, it is long, has two bands. Its coils in horse are easily distinguished from jejunal coils by their diameter, bands and sacculations.  Rectum  The rectum is continuation of descending colon as it enters the pelvis. It has peritoneal and retroperitoneal parts, and has no bands or sacculations.  Before ending at short anal canal, the rectum enlarged forming ampulla recti which is very prominent in horse, but absent in sheep and goat.  The relation of rectum varies in both sexes. In males, it is related ventrally to urinary bladder and accessory genital glands, while in females it is related to uterus and vagina.  Anal canal - It is the short terminal portion of digestive tract. The anus is the terminal orifice. - The external and internal sphincter muscles surround anus and keep opening closed. - Striated external sphincter M. arises from caudal vertebrae, but internal sphincter M.is the thickened continuation of circular smooth muscle coat of rectum.  The liver The liver is the largest gland in the body. Functions : -Secretion of bile for fat digestion. -Metabolic process (fat, carbohydrate, protein). -Storage fat, glycogen and vitamins. -Blood formation ( RBCs in fetal life , blood protein) -Secretion of heparin. - Detoxication. Position:  Depends on the species, but generally it is situated in intrathoracic part of the abdominal cavity mostly to the right of median plane. Color:  It depends on amount of blood it contains, species , age and nutritional state of animal.  In general, the liver is reddish brown in color. Size and weight:  They depend on species, age, and condition of animal.  Because it stores fats and glycogen, it weights more in well fed animals than in emaciated one.  The weight decreases with age.  Anatomical description: It has two surfaces; parietal and visceral and four borders; dorsal, ventral, right and left. # Parietal surface: convex, faces mostly cranially, related to diaphragm. # Visceral surface: - concave, faces mostly caudally, related to stomach, intestine, pancreas. - It presents some impressions as gastric, duodenal, colic and pancreatic.It presents hepatic porta. # Dorsal border: is rounded, presents some impression; esophageal, caval and renal. # Ventral, right and left borders: are sharp ventral border is marked by presence of interlobar fissures. Hepatic porta:  It is a depression in visceral surface through which, portal vein, hepatic artery and hepatic nerve plexus enter, but hepatic ducts and lymph vessels leave the liver. Lobation of liver: - The liver is divided by two imaginary lines into three lobes; right, intermediate and left. - The right line between caudal vena cava and gall bladder. - The left line between esophageal notch and umbilical fissure which contains falciform and - The right and left lobes are subdivided into medial and lateral lobes. - Intermediate lobe is subdivided by the porta into supraportal (caudate lobe) and infraportal (quadrate lobe) parts. - Supraportal part is subdivided into caudate and papillary processes. - The typical lobation of liver presents in dog (7 Lobes): RM lobe, RL lobe, LM Lobe, LL lobe,Caudate Process, Papillary Process and Quadrate Lobe. Fixation of liver: 1-Non peritoneal fixation: - Pressure of surrounding viscera. - Continuation of hepatic veins into caudal vena cava. - Structures enter and leave hepatic porta.  2 -Peritoneal fixation: 1. Hepatogastric and hepatoduodenal ligaments (lesser omentum): between hepatic porta and lesser curvature of stomach and cranial part of duodenum respectively. 2. Coronary ligament: between liver and diaphragm. 3. Right and left triangular ligaments: attach liver to diaphragm and sublumber region. 4. Falciform ligament: between umbilical fissure and sternal part of diaphragm. 5. Round ligament: represents obliterated umbilical vein. 6. Hepatorenal ligament: connects right lobe and caudate process with right kidney. Excretory apparatus: - It consists of hepatic ducts , which unite to form common hepatic duct - Gall bladder has a cystic duct which joins common hepatic duct forming bile duct. - In some species the bile duct opens with major pancreatic duct into duodenum. Vessels and nerves: - Nutritional arterial supply from hepatic artery and functional blood supply from portal vein. The hepatic veins join caudal vena cava. - The lymph is drained by hepatic lymph nodes. - The nerves from hepatic plexus ( sympathetic and parasympathetic fibers).  Gall bladder - Function: It stores bile temporarily and discharges it into duodenum. - Position: It lies on fossa on visceral surface of liver between quadrate and right medial lobes. - Shape: It is a pear-shaped or conical sac - Formation: It consists of fundus, body and neck which continues with cystic duct. - Comparative: It projects from ventral border of liver only in ruminants. - It is absent in equines and camel.  liver Dog Pig Rum. Horse Camel Centrally Almost Entirely Obliquely Mainly to in central in in right in intrath. right side Position intrath. intrath. part side of part of of abd. part of of abd. abd. abd. cavity abd. cavity w cavity cavity. 3/5 cavity. greater part to right, to right side 2/5 to left Interlobar Deep Deep Not Partially Partially fissures clear fissured fissured (lack) lobulation Not Distinct Not Not Distinct distinct distinct distinct  liver Dog Pig Rum. Horse Camel (7 lobes) (6 lobes ) ( 5 lobes) ( 5 lobes ) ( 6 lobes) Typical Papillary Right & left Right lobe Right lobe lobation , process lobes undivided. undivided. all lobes are absent. undivided. Papillary Numerous Quadrate Caudate irregular present process is fissures on Left lateral lobe process in absent. ventral is the small , L.R Quadrate border Lobes not reach →tongue lobe has largest one ventral shape several small border S.R → fissures on prismatic ventral border Present Absent Present Present Present Renal impression Not project As dog Projects Absent Absent Gall from ventral border from ventral bladder border. Ligaments Dog Pig Rum. Horse Camel R. & L. -R. well Both Both well Both well Both well triangular developed absent developed developed developed -L. small Coronary well well well well developed developed developed developed developed Hepatorenal Present Absent Present Present Present Falciform Small Absent in Absent in Present Present adult adult Round Present In young In young Present Present Lesser Extends As dog Extends As dog As rum. omentum from liver from liver to to stomach omasum, & abomasum duodenum & duodenum  Pancreas - It is a soft lobulated organ, lies dorsally in intrathoracic part of abdominal cavity mainly to right of median plane. It is associated to the duodenum. - Its color is light with a pinkish tinge. Formation : - It consists of the three parts; body, right lobe and left lobe. - The body: is the middle part which lies against cranial part of duodenum. - It is either notched or perforated by portal vein. - The right and left lobes: are two branches diverge from body to corresponding side. The right lobe continues along descending duodenum in all animals except horse. Excretory system:- The pancreas has two excretory ducts: 1-The main or major pancreatic duct which opens with the bile duct in the duodenum. 2-The accessory or minor pancreatic duct which opens dorsally in the duodenum. =One of them may be absent in some species.  pancreas Dog Pig Rum. Horse Body Centrally Extensive Small large situated Relation w Portal notch Portal ring Portal Portal ring portal notch vein Right lobe Long narrow Small Long Short forms U-shaped w L. lobe Left lobe As R.lobe Large Wide Long Duct system: Dog Pig L. Rum. S. Rum. Horse - Common hepatic d. + + + + + - Cystic d. + + + + - - Bile d. + + + + - -Main pancreatic d. + - - + + --Accessory + + + - + pancreatic d.  Spleen Position : It is situated in the intrathoracic part of left abdominal cavity. But its position is variable depending on the state of fullness of the stomach, especially in dog. Anatomical description: It has 2 surfaces, 2 borders, 2 extremities: parietal surface is convex and related to the diaphragm, visceral surface in most species has hilus which divides this surface into small cranial gastric surface and large caudal intestinal Fixation of the spleen: Gastrosplenic lig. Renosplenic lig. Phrenicosplenic lig. Spleen Dog Pig L. Rum. S. Rum. Horse Shape Irregular Long Flat, Goat is Comma w. tongue narrow w. elongat rectangu wide shape w. pointed ed oval lar dorsal end broad ventral end with and Sheep is pointed ventral extr. uniform triangula ventral And width r end constricted in the middle  Dog Horse Ox Pig Goat