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Quas legere an pri. Omnes reformidans eu pri, qui eu graeci quodsi probatus, no minim salutatus patrioque mea. Latine offendit an eos. Te facilis menandri vel, porro invidunt eu per, no esse blandit dissentiet cum. Fabulas temporibus comprehensam in ius.

• Transport of tissue fluid formed in the capillary bed.  Interstitial fluid derived from blood bathes the cells and provides oxygen and nutrients to the cells and then most of the fluid passes back into the bloodstream carrying carbon dioxide and waste products. An amount of this interstitial fluid is drained by the lymphatic system.
• Lymph nodes perform a filtering function by removing harmful substances (bacteria, virus etc) from the interstitial fluid
• Most of the lymphocytes are formed in the lymph glands
• Intestinal lacteals help in the absorption of fat and protein from food (this gives lymph fluid the rich milky colour)

Discuss the major lymphatic channels?

Thoracic duct- this is the largest lymphatic channel in the body extending from L1 to the root of the neck.  It begins as either a plexus by the confluence of several lymphatics on the posterior abdominal wall or a dilatation termed the cisterna chyli. It drains lymph from the left arm (via left subclavian), left neck and head (left jugular, left thorax, left upper abdomen (to umbilicus), both sides of the abdomen below the umbilicus and both lower limbs. It terminates either into the junction of the left internal jugular and subclavian veins or one of those veins.

Right lymphatic duct- It drains right head, neck, right arm (via right jugular trunk), right thorax (via right subclavian trunk) and right upper abdomen to umbilicus (via right Brachiocephalic trunk). It drains into the junction of the right internal jugular and right subclavian veins or each of these veins separately.

Discuss the abdominal lymph nodes?

They lie in front of the lumbar vertebral bodies near the aorta and are in three groups: preaortic, paraaortic and retroaortic

Preaortic nodes: lie in front of the aorta near the vessels of the name

Coeliac- drain gastric, hepatic and pancreaticosplenic node

Superior mesenteric- drain nodes in the mesentery

Inferior mesenteric- drain nodes in the mesentery

Efferent vessels from pre aortic nodes form intestinal trunks and help in the formation of the thoracic duct

Paraaortic nodes (left and right) – drains kidneys, adrenal glands, ureter, posterior abdominal wall, testis, ovary, uterus and uterine tubes.

External iliac lymph nodes receive lymphatics from inguinal nodes, external genitalia, vagina, and cervix; they drain into the common iliac nodes. Internal iliac and sacral lymph nodes receive afferents from all the pelvic viscera (e.g., cervix, prostate, and rectum) and from the perineum, buttock, and thigh; they drain into the common iliac nodes. Common iliac lymph nodes drain the two preceding groups and send their efferent’s to the paraaortic nodes, which also receives the afferents of the testis and ovary.

Efferent’s from paraaortic nodes form paired lumbar trunks. The lumbar trunks empty in the cistern chyli. Cisterna chyli is a dilated sac at the lower end of the thoracic duct.

Retroaortic Lymph Nodes – these nodes drain the posterior abdominal wall. These may be the peripheral nodes of the paraaortic group

Useful read: Link

The abdominal aorta begins at the aortic opening in the diaphragm (at about T12) and descends anterior to the vertebral bodies and ends at L4 by dividing into the right and left common iliac arteries.

Each common iliac artery divides into the external and internal iliac arteries. The external iliac artery passes posterior to the inguinal ligament to become the femoral artery. The external iliac artery gives off the inferior epigastric and deep circumflex iliac arteries. The internal iliac artery supplies most of the pelvis via parietal and visceral branches.

The parietal branches of the internal iliac artery include the iliolumbar, lateral sacral, obturator, superior and inferior gluteal, and internal pudendal arteries. The branches of the internal pudendal artery include the inferior rectal artery and vessels that supply the scrotum (or labia), perineum, bulb of the penis (or vestibule), and urethra.

The visceral branches of the internal iliac artery includes the umbilical and superior and inferior vesical arteries, the uterine artery (or the artery of the ductus deferens), and the vaginal and middle rectal arteries.

Discuss the branches of abdominal aorta?

Parietal branches

• Paired lumbar arteries- supply the muscles of the back and provide spinal branches.
• Median sacral artery- unpaired artery arising near the bifurcation and descends to the coccygeal body.

Visceral branches

Paired middle suprarenal, renal gives rise to inferior suprarenal arteries), and gonadal (ovarian/testicular) arteries.

Coeliac trunk

It is the artery to the caudal part of the foregut, i.e., as far as D2. It divides into

• Left gastric- it runs along the lesser curve and anastomoses with the right gastric artery
• Splenic artery- it runs to the left along the upper border of pancreas.  It gives off pancreatic branches, left gastroepiploic artery (runs along greater curve), short gastric arteries and splenic branches.
• Common hepatic artery- divides into the hepatic artery proper, the right gastric artery, and the gastroduodenal artery. The hepatic artery proper divides into right and left branches, the former of which gives off the highly variable cystic artery.  The gastroduodenal artery gives off the posterior superior pancreaticoduodenal artery, and divides into the anterior superior pancreaticoduodenal and right gastroepiploic arteries.

Superior mesenteric artery

It supplies the midgut, i.e., from D2 to the proximal 2/3rd of the transverse colon. It arises from the front of the aorta inferior to the origin of the coeliac trunk.  Its branches include:

• Inferior pancreaticoduodenal artery (it divides into anterior and posterior components)
• Jejunal and ileal arteries to the small intestine.
• Ileocolic artery
• Right colic artery
• Middle colic artery

Inferior mesenteric artery

It supplies the hindgut, i.e., from the distal third of the transverse colon to the rectum. It arises from the aorta a little superior to its bifurcation. Its branches are

• Left colic
• Sigmoid arteries
• Superior rectal artery- it is the continuation of the inferior mesenteric artery

Venous blood from the stomach and small intestine is collected by the portal vein. The portal vein is formed posterior to the neck of the pancreas, by the union of the superior mesenteric and splenic veins. The inferior mesenteric vein ends by joining the splenic vein.  The left and right gastric veins drain directly into the portal vein. The right gastroepiploic veins drain into the superior mesenteric vein or splenic vein or directly into the portal vein. The left gastroepiploic vein and short gastric veins drain into the splenic vein.

Discuss portal-systemic anastomoses?

The portal and systemic venous system communicates in several locations. These anastomoses are important clinically. When portal system is blocked, the blood from the GIT can still reach the right atrium through these anastomoses (they dilate and become varicose when portal system is obstructed as well as causing reversed flow of portal blood into systemic veins). The important anastomoses are as follows:

• Gastro oesophageal region-left gastric vein branches anastomose with the oesophageal veins that drain into the azygous vein.
• Anorectal region- superior rectal vein anastomoses with the middle (branch of internal iliac) and inferior rectal vein (branch of internal pudendal)
• Paraumbilical region- Para-umbilical veins in the falciform ligament connect the portal vein with subcutaneous vessels around the umbilicus, and these last drains into the epigastric veins and thence into the venae cavae
• Retroperitoneal region- splenic and pancreatic vein tributaries anastomose with the left renal vein. Numerous, small retroperitoneal veins drain the “bare” (i.e., non-peritonealised) surfaces of the organs also communicate with the veins of the diaphragm.

It is the largest single mass of lymphoid tissue in the body. It is related to the 9-11th ribs on the left side. The spleen is completely surrounded by the peritoneum except at the hilum. It is supplied by the splenic artery. The splenic artery branches supply spleen as end arteries.  Thus, obstruction of one of them lead to splenic infarction. Spleen is drained by the splenic vein. Splenic vein joins with the superior mesenteric vein posterior to the neck of the pancreas to form the portal vein.

Splenic lymphatics drain into pancreaticosplenic nodes and then to coeliac nodes.

Spleen has a connective tissue capsule, which extends inward to divide the organ into lobules. The parenchyma of the spleen is termed the pulp of the spleen. There is red pulp and white pulp. Red pulp consists of large thin-walled blood vessels, the splenic sinusoids, interposed between reticular connective tissue, the splenic cords. Within the red pulp, there are small rounded white areas, the white pulp, formed by lymphoid tissue.

The spleen filters blood and removes pathogens and old erythrocytes. Like other lymphatic tissue, it produces lymphocytes.

Discuss splenectomy?

A splenectomy causes no noticeable ill effects in most patients. However, this may uncommonly cause overwhelming post-splenectomy infection, usually caused by the encapsulated bacteria Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitides.

Most infections after splenectomy could be avoided by

• Appropriate and timely immunisation- vaccination (against pneumococci, meningococci and H. Influenza) should be performed at least two weeks before splenectomy, or as soon as possible after emergency splenectomy
• Antibiotic prophylaxis- lifelong prophylaxis with oral phenoxymethylpenicillin (or erythromycin for people who are allergic to penicillin) is advised although efficacy remain unclear
• Prompt treatment of infection.

It is a pear shaped organ that lies on the visceral surface of the liver. The GB is divided into a fundus, body and neck. The fundus is the wide end of GB that projects from the inferior border of the liver. The body of the GB lies in contact with the visceral surface of the liver. The neck of the GB is narrow and may have a dilatation called the Hartmann’s pouch. The duct of the GB (cystic duct) joins the common hepatic duct to form common bile duct.

GB is supplied by the cystic artery branch of right hepatic artery

Lymphatic drainage is to cystic node (and then to hepatic and coeliac node)

The GB stores (30-60mls) and concentrates the bile secreted by the liver. The GB contracts and release bile in response to a meal.

Discuss the effects of cholecystectomy?

GB is a vestigial organ like the appendix

Liver normally produces 1-1.5 litres of bile a day. It is constantly produced and thus there is a steady amount of bile entering the duodenum. Some of it enters the GB as it comes down the duct and stored there.

The bile that constantly flows into the duodenum is adequate for fat digestion. Thus cholecystectomy does not lead to fat maldigestion.  However, a rich fatty meal can sometimes cause a degree of diarrhoea.

Discuss the entero hepatic circulation for bile acids?

Liver produces bile acids (cholic acid and chenodeoxycholic acid) from cholesterol. These bile acids are conjugated with glycine and taurine to form water soluble primary conjugated bile acids (also called bile salts).  These bile salts are secreted with bile in the intestine. Bile salts are ionised (due to pH of the intestine) and dehydroxylated (by the intestinal bacteria) to from primary and secondary conjugated bile salts (which are still water soluble). These conjugated bile salts are actively reabsorbed in the ileum.   Liver extracts bile acids from portal blood and secretes it again in the canaliculi. This is the enterohepatic circulation.

95% of the bile acids which are delivered to the duodenum will be recycled by the enterohepatic circulation. The rest is lost in faeces and replaced by de novo synthesis.

Pic 1: Gallbladder wall: showing all layers from mucosa to serosa. Two Rokitansky-Aschoff sinuses underlie the mucosa in centre & right photo.

• Herophilus, Greek surgeon first described pancreas. Wirsung discovered the pancreatic duct in 1642
• Location- 12-15 cms long located posterior to the stomach, across the posterior abdominal wall
• Function- both exocrine and endocrine gland. It secretes pancreatic juice that enters duodenum via pancreatic duct. It also secretes insulin and glucagon
• Parts- it has a head, neck, body and tail.
  • Head- located with the curve of duodenum. It has a prolongation called the uncinate process
  • Neck- is grooved posteriorly by the superior mesenteric vessels
  • Body- it has three surfaces; anterior, posterior and inferior. The body of the pancreas is intimately related to the splenic vein.
  • Tail-it passes between the two layers of the lienorenal ligament and its end contacts the hilum of the spleen

Discuss the ducts of the pancreas?

There are two ducts: main pancreatic duct (MPD) and an accessory one

MPD- it begins at the tail of the pancreas and runs (superficially beneath the posterior surface of pancreas) through the pancreas, receiving branches throughout its length. The MPD unites with the CBD to form the ampulla of Vater. There is a sphincter around the terminal part of MPD and around the ampulla of Vater (called sphincter of Oddi)

The accessory duct drains part of the head of the pancreas. Usually it is connected to the MPD, but in about 9% cases, it is a separate duct opening into the duodenum at the minor duodenal papilla (about 2 cms proximal to the ampulla of Vater).

Discuss the blood supply of pancreas?

Head-

Anterior and posterior superior pancreaticoduodenal artery (branches of gastroduodenal artery)

Anterior and posterior inferior pancreaticoduodenal artery (branches of superior mesenteric artery)

Body and Tail- splenic artery branches

Discuss the lymphatic drainage of pancreas?

• Pancreaticoduodenal nodes drain the head of the pancreas to the pyloric nodes (then to hepatic and coeliac nodes)
• Pancreaticosplenic nodes (lie along splenic artery on the superior border of pancreas) – drain the neck, body, and tail of the pancreas and are afferent to the coeliac nodes.
• Superior mesenteric nodes- also drain a portion of the pancreas.

Discuss the physiology of pancreas?

• It is both an exocrine and endocrine organ. Exocrine pancreas secretes digestive enzymes in the duodenum. Endocrine organ include islet of Langerhans the cells of which have four types of hormone secreting cells: A-cells secrete glucagon, B-cells secrete insulin, D-cells secrete somatostatin and F-cells secrete pancreatic polypeptide.
• Histology- 2 major components- acinar cells and ducts. These two constitute 80-90% of the pancreatic mass. 20-40 acinar cells coalesce into a unit called acinus.  Acinar cells secrete the digestive enzymes. Ductal system; Acinus small intercalated ducts interlobular duct pancreatic duct
• Digestive juices;
  • Pancreas secrete 500-800 mls of digestive juices every day
  • Pancreatic juice contains amylase, lipase and proteases (trypsinogen, chymotrypsin, elastase, carboxypeptidase, and phospholipase) Amylase is the only pancreatic enzyme secreted in an active form.  Lipases emulsify and hydrolyse lipids in the presence of bile salts. Proteases are secreted as proenzymes. The duodenal enzyme, enterokinase, converts trypsinogen to trypsin. Trypsin, in turn, activates chymotrypsin, elastase, carboxypeptidase, and phospholipase.
  • Pancreatic juice also contains  water and electrolytes (esp. bicarbonate) secreted by the centroacinar and intercalated duct cells
  • Secretion of enzymes by pancreatic gland cells is stimulated by the hormone cholecystokinin which is released from the wall of the duodenum.  In addition the hormone secretin, results in the pancreas making bicarbonate rich fluid. Secretin – released from the duodenal mucosa in response to a duodenal luminal pH < 3

It is the largest abdominal organ. It is attached to the diaphragm and the anterior abdominal wall by the falciform ligament. The liver is surrounded by Glisson’s capsule of strong connective tissue.

Liver anatomy can be described using two different aspects: morphological anatomy and functional anatomy.

Morphological anatomy is based on external appearances

The falciform ligament on the diaphragmatic surface and left sagittal limb on the visceral surface divides the liver into the right and left anatomic lobes, which are very different from the functional right and left lobes.

On the visceral surface of the liver, there is an H shaped group of fissures and fossa. The crossbar of the H is the porta hepatis. It contains the portal vein, hepatic artery, hepatic ducts, nerves and lymphatics. The left sagittal limb of the H is the fissures containing the ligamentum teres and the ligamentum venosum. The right sagittal limbs of the H are fossae for the gallbladder and IVC.

In this morphological description, the quadrate and caudate lobe belongs to the right lobe of the liver.

Q= quadrate lobe, C= caudate lobe

Functional anatomy

Functionally the liver is divided into two lobes, right and left by a plane that passes through the gallbladder fossa and the fossa for IVC (i.e. left sagittal limb). Each lobe has its own arterial supply and venous and biliary drainage. Thus the caudate and most of quadrate lobe belong to the functional left lobe of liver.

Within each lobe the branches of portal vein and hepatic artery are consistent and divide each lobe into 4 vascular segments. So the liver is divided into eight functionally independent segments. Each segment has its own vascular inflow, outflow and biliary drainage. In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct. In the periphery of each segment there is vascular outflow through the hepatic veins.

Because of this division into self-contained units, each segment can be resected without damaging those remaining. For the liver to remain viable, resections must proceed along the vessels that define the peripheries of these segments.

Segment 1 (caudate lobe) is located posteriorly. It is not visible on a frontal view. On a normal frontal view the segments 6 and 7 are not visible because they are located more posteriorly. The right border of the liver is formed by segment 5 and 8. Although segment 4 is part of the left hemi liver, it is situated more to the right.

Right hepatic vein divides the right lobe into anterior and posterior segments
Middle hepatic vein divides the liver into right and left lobes. Left hepatic vein divides the left lobe into a medial (segment 4) and lateral part (segments 2 and 3). The right portal vein divides the right lobe of the liver into superior segments (7 and 8 ) and the inferior segments (5 and 6). During ultrasound it is easy to detect hepatic veins. Hepatic veins are then used to identify vascular segments.

Discuss caudate lobe?

The caudate lobe is often enlarged in cases of cirrhosis and the Budd-Chiari Syndrome. The reason for this is unclear. However, differences in different hormones, nutritional elements, and hepatotropic factors in the portal blood flow between the caudate lobe and the other segment of the liver may correlate with the hyperplastic change of the caudate. Caudate lobe drains directly into IVC (through hepatic veins) and may receive a specific pedicle independent of the portal vein.

Discuss the vascular and lymphatic supply of Liver?

Arterial supply of the liver

Liver has a dual blood supply

Hepatic artery (30%) – it carries oxygenated blood to the liver. The hepatic artery divides into right and left hepatic artery at the porta hepatis

Portal vein (70%) – It carries venous blood containing the products of digestion from the GIT. At the porta hepatis, portal vein terminates by dividing into right and left branches.

Venous drainage of the liver

Hepatic veins drain the liver into the IVC. Hepatic veins are formed by the union of the central veins in its lobules. There are superior (right, left and middle hepatic veins) and inferior group (6-18 small veins draining the right lobe) of hepatic veins.

Lymphatic drainage of the liver

Hepatic nodes along the hepatic vessels (these drain in coeliac nodes)

Some of the lymph vessels follow the hepatic veins to the vena cava foramen in the phrenic and mediastinal nodes.

Discuss the liver histology?

• Hepatic parenchyma can be divided into hexagonal lobules separated by sheets of connective tissue.
• The lobule is the structural unit of the liver, with portal triads (contains branches of portal vein, hepatic artery and bile ductule) at the vertices and a central vein in the middle.
• The parenchymal cells of the liver are hepatocytes. Hepatocytes make contact with blood in sinusoids, lined by highly fenestrated endothelial cells and populated with phagocytic Kupffer cells. The space between endothelium and hepatocytes is called the Space of Disse which collects lymph for delivery to lymphatic capillaries.
• Bile secreted by hepatocytes collect in channels called canaliculi (the basal faces of hepatocytes are joined together by junctional complexes to form canaliculi). These secretions flow toward the periphery of lobules and into bile ductules and interlobular bile ducts, ultimately collecting in the hepatic duct outside the liver.
• Terminal branches of hepatic artery and portal vein empty together and mix in the sinusoids of the liver. Blood flows through the sinusoids and empties into the central vein of each lobule. Central veins coalesce into hepatic veins, which leave the liver and empty into the vena cava.

Pic 1: Liver lobule

Pic 2: Hepatic lobule -Photo is centred on a lobule with central vein, visible sinusoids, a portal triad to the lower right, some fatty infiltration, and portions of surrounding lobules.

Pic 3: Hepatocytes -note the sinusoids converging on the central vein at the bottom

Pic 4: Bile duct -An interlobular bile duct is seen in longitudinal section, with a cross section of a portal vein branch to the right

Ref:

http://www.radiologyassistant.nl/en/4375bb8dc241d

The parts of the large bowel are:

Discuss the relations of rectum?

Anteriorly- the rectovesical pouch and bladder in males. Uterus, cervix and vagina in females

Laterally- ischial tuberosity and spine

Posteriorly- sacrum and coccyx

Discuss haemorrhoids and anal sphincters?

Internal haemorrhoids are varicosities of the branches of superior rectal veins and covered by mucous membrane and external haemorrhoids are varicosities of the branches of inferior rectal veins and are covered by skin

Anal sphincters- Anal canal has an external and internal sphincters- both must relax before defecation can occur. The external sphincter is voluntary and surrounds the inferior 2/3rd of the anal canal. The internal sphincter is involuntary and surrounds the superior 2/3 rd of the anal canal

Discuss the function of large bowel?

The primary function of the large bowel is the reabsorption of water and inorganic salts. It also secretes mucus, which acts as a lubricant during the transport of the intestinal contents.

Discuss the histology of large bowel?

Mucosa- is flat with no villi or plica circularis as in small bowel

Surface epithelium- is composed of tall columnar epithelium and goblet cells. Paneth cells (secreting antibacterial substances like lysozyme) are usually present in the caecum & proximal colon (usually confined to the crypt bases). Crypts of Lieberkuhn are straight, narrow and mostly unbranched, separated by a thin rim of lamina propria

Lamina propria- There is only little lamina propria squeezed between glands. It is composed of loose, areolar connective tissue which appears highly cellular due to the presence of chronic inflammatory cells in the superficial part of the lamina propria.

Inflammatory cells in the deeper part and separation of crypt bases from muscularis mucosae by plasma cells and lymphocytes is indicative of IBD.

Muscularis mucosae- 2 layers inner circular and outer longitudinal

Submucosa

Loose connective tissue, also contains Meissner’s plexus of autonomic nerve fibres

Muscle layer- inner circular and outer longitudinal layer of muscle. The outer longitudinal muscle layer forms three flattened strands, the taenia coli. Only a thin layer of longitudinal muscle surrounds the inner circular muscle layer between the taenia coli. The taenia converges at the root of the appendix and the rectum.

Serosa or adventitia- forms small pouches (appendices epiploicae) filled with fatty tissue along the large intestine.

Source: National Cancer Institute

Jejunum begins at the DJ flexure. Together the jejunum and ileum are about 5-8 metres long; jejunum constitutes about two-fifths and ileum comprises the remainder. There is no clear line of demarcation between jejunum and ileum.

Jejunum is thicker, more vascular and redder than ileum. The mucosal folds (valvulae conniventes) are well developed in jejunum, whereas they are small in the proximal part of ileum and absent in its distal part.

The jejunum and ileum is suspended by a mesentery from the posterior abdominal wall. The blood vessels, lymphatics and nerves run between the two layers of the mesentery.

Discuss the blood supply of jejunum and ileum?

Jejunal and ileal branches from the superior mesenteric artery. The arteries unite to form arches from which vasa recta raise and supply the intestine.

Discuss the lymphatic drainage of the jejunum and ileum?

The lymph drain into the mesenteric nodes which then drain in the superior mesenteric lymph nodes. The mesenteric nodes are situated in three positions:

• Close to the wall of the intestine
• Amongst the arterial arches
• Along the superior mesenteric artery

What is Meckel’s diverticulum?

It is a remnant of the vitello-intestinal duct that occasionally persists in the adult as an ileal (Meckel’s) diverticulum, which is situated near the ileocolic junction. It may contain gastric or pancreatic tissue, and inflammation of the diverticulum may simulate acute appendicitis.

Discuss the histology?

Mucosa

Epithelium

Small intestinal mucosa is specially adapted to increase the luminal surface area to facilitate absorption. The mucosa and submucosa form crescent shaped folds called plicae circulars. These extend around one-half to two-thirds of the circumference of the lumen of the small intestine. Plicae circulars are absent from proximal parts of the duodenum and the distal part of the ileum. The entire intestinal mucosa forms intestinal villi (about one mm long). The surface of the villi is formed by a simple columnar epithelium. Each absorptive cell or enterocyte of the epithelium forms numerous microvilli. Plicae circulars, villi and microvilli tremendously increase the absorptive surface area
Crypts of Lieberkuhn- these are simple tubular glands opening between the intestinal villi. They extend through the lamina propria down to the muscularis mucosae. Function of the crypts of Lieberkuhn:

• Paneth cells located at the bottom of the crypts release antibacterial substances (e.g. lysozyme) to control infections.
• Undifferentiated cells close to the bottom of the crypts regenerate the epithelium.
• Secretion of intestinal juice (about 2 litres/day).

In addition to enterocytes, the epithelium is composed of mucus-secreting goblet cells and endocrine cells. Endocrine cells secrete gastrin, somatostatin, cholecystokinin and secretin. Cholecystokinin stimulates pancreatic digestive juice secretion and the contraction of the gall bladder. Secretin also stimulates the pancreas to release pancreatic juice rich in bicarbonate ions. Secretin also amplifies the effects of cholecystokinin.

Lamina propria- is cell rich. Lymphocytes form solitary lymphoid nodules in the lamina propria. These lymphoid nodules may form large aggregation called Peyer’s patches in the ileum.

Muscularis mucosae- extend into the intestinal villi, where the smooth muscle cells form a longitudinal bundle in the centre of the villi.

Submucosa

The submucosa contains glands (Brunner’s glands) only in the duodenum.
Muscle layer
Serosa

Pic 1 Anatomy

Pic 2 Jejunal mucosa

Pic 3 Jejunal Goblet cell