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Home , Anal sinuses, Anal valves, Duodenojejunal flexure, Pararectal lymph nodes, Pectinate line

ABDOMINAL CAVITY the third lecture Abdominal cavity – third part

Small intestine (small bowel) (large bowel) Lymphatic drainage of the intestine Innervation of the intestine Unpaired visceral branches of the

Consists of: - - -

Extends from the to the ileocecal junction Duodenum

First and shorter part of the small intestine The widest and most fixed part Pursues a C-shaped course around the head of the Begins at the pylorus on the right side and ends at the duodenojejunal junction () on the left side (at the level of the L2 vertebra, 2 to 3 cm to the left of the midline) Duodenum

Divides into four parts: superior (1st), descending (2nd), horizontal (3rd), ascending (4th). Superior (first) part of duodenum

Short, aproximately 5cm Lies anterolateraly to the body of L1 vertebra Ascends from the pylorus and is overlapped by the liver and gallbladder The first 2 cm, immediately distal to the pylorus has a mesentary and is mobile- - ampulla (duodenal cap) Ampulla superiorly attached by the hepatoduodenal ligament and the greater omentum inferiorly Relationship of the duodenum Superior (1st part)- L1 vertebra anterior: gallblader quadrate lobe of liver posterior: common bile duct, gastroduodenal , portal , inferior vena cava superior: neck of gallblader inferior: neck of pancreas Descending (2nd) part of the duodenum

Runs inferiorly Curving around the head of the pancreas Initially lies to the right and parallel to the inferior vena cava The common bile and pancreatic ducts enter its posteromedial wall (the eminence- the ) Entirely retroperitoneal (secondary retroperitoneal) Relationship of the duodenum Descending (2nd part)- L2/L3 vertebra anterior: , transverse mesocolon, coils of small intestine posterior: hilum of right , renal vessels, ureter, psoas major medial: head of pancreas, pancreatic duct, common bile duct The inferior (horizontal) part of the duodenum Runs transversely to the left, passing over the inferior vena cava, aorta and L3 vertebra Is crossed by the superior mesenteric artery and vein and the root of the of the jejunum and ileum The anterior surface- covered with peritoneum Superiorly – the head and uncinate process of pancreas Posteriorly- separated from the vertebral column by the right psoas major, inferior vena cava, aorta and the right testicular/ovarian vessels Relationship of the duodenum Horizontal (3rd) part, anterior to L3 vertebra anterior: superior mesenteric artery superior mesenteric vein, coils of small intestine posterior: right psoas major, right ureter, inferior vena cava, abdominal aorta superior: head and uncinate process of pancreas, superior mesenteric artery superior mesenteric vein The ascending part (fourth) of the duodenum Runs superiorly and along the left side of the aorta to reach the inferior border of the body of the pancreas Curves anteriorly to join the jejunum at the duodenojejunal junction, takes the form of an acute angle – the duodenojejunal flexure (supported by the ligament of Treitz) Two or three inconstant folds and fossae are around the duodenojejunal junction If the loop of intestine enters this fossa, it may strangulate Ligament of Treitz Supports the duodenojejunal flexure Suspensory muscle Composed of a slip of skeletal muscle from diaphragm and a fibromuscular band of smooth muscle from the third and fourth parts of the duodenum Contraction of this muscle widens the angle of the flexure, facilitating movement of the intestinal contents Passes posterior to the pancreas and splenic vein and anterior to the left Relationship of the duodenum Ascending (4th)part, left of L3 vertebra anterior: the root of mesentery, coils of jejunum posterior: left psoas major, left margin of aorta medial: head of pancreas superior: body of pancreas Abdominal aorta

Unpaired visceral branches: celiac trunk superior mesenteric artery inferior mesenteric artery of the duodenum From the celiac trunk (via the gastroduodenal artery) and the superior mesenteric artery The anastomosis between them occurs approximately at the level of entry of the common bile duct The pancreaticoduodenal arteries (superior and inferior) lie in the curve between the duodenum and the head of the pancreas of duodenum Follow the arteries and drain into the portal vein or through the superior mesenteric and splenic veins Lymphatic vessels of the duodenum Anterior- drain into the pancreaticoduodenal nodes located along the superior and inferior pancreatico- duodenal arteries Anterior- also drain into the pyloric lymph nodes that lie along the gastroduodenal artery Posterior- drain into the superior mesenteric nodes

Efferent lymphatic vessels- drain into the celiac lymph nodes (form the intestinal lymphatic trunk) The nerves of duodenum

From the vagus and sympathetic nerves through the celiac and superior mesenteric plexuses on the pancreaticoduodenal arteries Jejunum and ileum The jejunum begins at the duodenojejunal flexure The ileum ends at the ileocecal junction – the union of the terminal ileum and the Together: 6 to 7 meters long The jejunum constituting approximately two-fifths and the ileum approximately three-fifths No clear line of the demarcation between the jejunum and the ileum The differences between jejunum and ileum Color: deeper red (paler pink) Caliber: 2-4cm (2-3cm) Wall: thick and heavy (thin and light) (plicae circulares): large, tall and closely packed (low and sparse, absent in distal part) Lymphoid nodules (Peyer’s patches): few (many) The differences between jejunum and ileum

Vascularity: greater (less) Vasa recta (straight arteries): long (short) Loops of arcades: a few large (many short) Jejunum and ileum

The layers of small intestine Intestinal villi - tiny projections of the - increase the internal absorptive surface area of the intestinal wall Lacteals

Specialized lymphatic vessels in the intestinal villi Absorb fat Drain in turn into lymphatic vessels between the layers of the mesentery Ileal (Meckel’s) diverticulum

The most common problem that occurs in the digestive system Congenital disease A remnant of the proximal part of the embryonic yolk stalk 50 cm from the ileocecal junction (30-60 cm in infants) Occurs in 1 out of every 50 people Diffucult to diagnose Symptoms are mistaken for appendicitis or a peptic ulcer The mesentery of the small intestine A fan-shaped fold of peritoneum- attaches the jejunum and ileum to the posterior abdominal wall

Extends from the duodenojejunal juction on the left side of the L2 vertebra to the ileocolic junction and the right sacroiliac joint

The average breadth of the mesentery from its root to the intestinal border is 20 cm The root of the mesentery Crosses:

Ascending and horizontal parts of the duodenum Abdominal aorta Inferior vena cava Right ureter Right psoas major Right testicular/ovarian vessels Superior mesenteric artery

Arises from the abdominal aorta at the level of the L1 vertebra, approximately 1 cm inferior to the celiac trunk Runs between the layers of the mesentery, Sends 15 to 18 branches to the jejunum and ileum. Arterial arcades (arches, loops) - the union of the branches, give rise to straight arteries (the vasa recta) Relations of superior mesenteric vein and artery in root of mesentery

Lies anterior and to the right of the superior mesenteric artery in the root of mesentery of the small intestine Superior mesenteric vein

Ends posteriorly to the neck of the pancreas Unites with the splenic vein to form the portal vein Lymph vessels and nodes of the small intestine The lymphatic vessels pass between the layers of the mesentery The lymph nodes are close to the intestinal wall (juxta- intestinal), among the arterial arcades (mesenteric) and along the proximal part of the superior mesenteric artery (superior, central) Efferent vessels from mesenteric lymph nodes drain to the superior mesenteric (central) lymph nodes From the terminal ileum through ileocolic lymph nodes Innervation of the small intestine Presynaptic sympathetic fibers reach celiac and superior mesenteric ganglia (prevertebral) through greater and lesser splanchnic nerves Parasympathetic fibers (presynaptic nerves) derive from posterior vagal trunk and synapse with intrinsic postsynaptic neurons in the wall (Auerbach plexus- myenteric plexus) Referred site – umbilical region Innervation of the small intestine

Sympathetic stimulation – reduces motility and secretion of the intestine and acts as vasoconstrictor (reducing or stopping digestion and making blood (and energy) available for fleeing or fighting Parasympathetic stimulation increases motility and secretion of the intestine, restoring digestive activity Large intestine

Consists of:

Cecum with

Colon: ascending, transverse, descending, sigmoid

Rectum and The large intestine The differences between small and large intestine

Teniae coli (omental, mesocolic, free)- three thickned bands of muscle Haustra- sacculations of the colon between the teniae Omental appendices- small fatty projections of the omentum Caliber- the internal diameter is much longer Semilunar folds (internal surface) The cecum

The first part of the large intestine Continuous with the A blind intestinal pouch Approximately 7.5cm in both length and breadth Lies in the right lower quadrant (iliac fossa) Lies inferior to the junction of the terminal ileum and the cecum Ileocecal (ileal) orifice

The terminal ileum enters the cecum obliquely and partly invaginates into it

Formed by folds or lips (superior and inferior)

The folds meet laterally to form ridges (the frenula of the valve: anterior and posterior) Ileocecal valve The circular muscle- poorly developed around the orifice The valve- unlikely to have any sphincteric action in terms of controlling passage of the intestinal contents from the ileum into the cecum The opening- usually closed by tonic contraction The valve probably does prevent reflux from the cecum into the ileum as contractions occur to propel contents up to the colon The vermiform appendix

A blind intestinal diverticulum 6-10 cm length Arises from the posteromedial aspect of the cecum inferior to the ileocecal junction Has a short triangular mesentery – mesoappendix, which attaches to the cecum and the proximal part of the appendix The position of the vermiform appendix Variable

Usually retrocecal toward the right colic flexure(64%) or pelvic (32%) or other (subcecal, paracecal, preileal, postileal, subileal)

May project inferiorly toward or across the pelvic brim

The anatomical position determines the symptoms and the site of muscular spasm and tenderness when the appendix is inflammed The base of vermiform appendix- tenderness of two points McBurney point - one third of the distance along the oblique spinoumbilical line, joining the right anterior superior iliac spine to the umbilicus Lanz point- one third of the distance along the line connecting the anterior superior iliac spines The arteries of the cecum

The ileocolic artery, terminal branch of the superior mesenteric artery

The appendicular artery, a branch of the ileocolic artery supplies the vermiform appendix The ascending colon

The second part of the large intestine Passes superiorly on the right side of the abdominal cavity from the cecum to the right lobe of the liver, where turns to the left at the right colic flexure (hepatic flexure) Lies retroperitoneally (secondary retroperitoneal) The transverse colon

The largest and most mobile part of the large intestine Aproximately 45 cm long Crosses the abdomen from the right colic flexure- hepatic flexure (at the level of VIII rib) to the left colic flexure, where it bends inferiorly to become The left colic flexure (splenic flexure)

More superior, more acute and less mobile than right colic flexure

Lies anterior to the inferior part of the left kidney and attaches to the diaphragm through the phrenicocolic ligament (at the level of VII rib) The transverse mesocolon

Loops down, often inferior to the level of the iliac crests

Adherent or fused with the posterior wall of the omental bursa

The root lies along the inferior border of the pancreas The descending colon Passes retroperitoneally from the left colic flexure into the left iliac fossa, where it is continuous with the

Passes anterior to the lateral border of the left kidney

Paracolic gutter on its lateral aspect The sigmoid colon

S-shaped loop of variable length Usually approximately 40 cm Links the descending colon and the Extends from the iliac fossa to the third sacral segment where it joins the rectum The termination of the teniae coli, approximately 15 cm from the anus indicates the rectosigmoid junction The root of the sigmoid mesocolon Has an inverted V- shaped attachment Extending first medially and superiorly along the external iliac vessels and then medially and inferiorly from the bifurcation of the common iliac vessels to the anterior aspect of the sacrum The left ureter and the division of the common iliac artery lie retroperitoneally, posterior to the apex of the root The intersigmoid recess The layers of the colon Colonoscopy The arterial supply to the colon Ascending colon and right colic flexure: - from the ileocolic and right colic arteries (superior mesenteric artery)

Transverse colon: - mainly from middle colic artery (superior mesenteric artery)

Descending and sigmoid colon - from left colic and superior sigmoid arteries (inferior mesenteric artery) Venous drainage of colon Through the superior mesenteric vein (ascending and transverse colon)

Through the inferior mesenteric vein (descending and sigmoid colon), flows into the splenic vein and then to the portal vein on its way to the liver Venous drainage of the colon Lymph vessels and nodes of colon From ascending colon through epicolic, paracolic lymph nodes, next to the ileocolic and right colic nodes

From transverse colon through the epicolic, paracolic and middle colic lymph nodes

From the descending and sigmoid colon through the epicolic and paracolic nodes, then to the left colic nodes Pathway of the lymph from the colon

Lymphatic vessels Epicolic lymph nodes Paracolic l.n. (Appendicular l.n.) Intermediate (right, middle, left) l.n. Superior mesenteric l.n. (Inferior mesenteric l.n.) Intestinal lymphatic trunk Chyle cistern Thoracic duct Left venous angle The innervation of the colon Superior mesenteric nerve plexus (sympathetic and parasympathetic nerve fibers) : ascending and transverse colon The innervation of the colon Lumbar part of the sympathetic trunk and superior hypogastric plexus (sympathetic nerves) and the pelvic splanchnic nerves (parasympathetic nerves): descending and sigmoid colon Hirschsprung's disease A condition that affects the large intestine (colon) and causes problems with passing stool Is present when a baby is born (congenital) and results from missing nerve cells in the muscles of part or all of the baby's colon. The rectum Part of the alimentary tract continuous proximally with the sigmoid colon and distally with the anal canal The rectosigmoid juction lies anterior to the S3 vertebra Follows the curve of the sacrum and coccyx, forming the sacral flexure of the rectum Has an S-shape when viewed laterally Ends anteroinferior to the tip of the coccyx by turning sharply posteroinferiorly (anorectal flexure)- perforates the pelvic diaphragm to become the anal canal The rectum Demonstrates three sharp lateral flexures (superior, intermediate and inferior) when viewed anteriorly because of the presence of three internal infoldings (transverse rectal folds) The ampulla- the dilated terminal part of the rectum, lying directly above pelvic diaphragm and anococcygeal ligament The ampulla- receives and holds fecal mass until it is expelled during defecation The arteries of the rectum The superior rectal artery- the continuation of the inferior mesenteric artery Two middle arteries- arising from the inferior vesical arteries The inferior rectal arteries from the internal pudendal arteries Veins of the rectum

Blood drains through the superior, middle and to the portal and systemic veins Lymphatic drainage of the rectum

From the superior half of the rectum through the and then to the lumbar lymph nodes (lumbar lymphatic trunks form a chyle cistern)

From the inferior half of the rectum into the internal iliac lymph nodes The innervation of the rectum

Sympathetic supply from lumbar part of the symphathetic trunk and the superior hypogastric plexus Parasympathetic supply from the pelvic splanchnic nerves by the right and left inferior hypogastric plexuses Anal canal The terminal part of the large intestine Extends from the upper aspect of the pelvic diaphragm to the anus, external outlet of the 2.5 to 3.5 cm long Begins where the rectal ampulla narrows at the level of the U-shaped sling formed by puborectalis muscle Surrounded by internal and external anal sphincters, descends posteroinferiorly between the anococcygeal ligament and the perineal body The

A large, voluntary sphincter Forms a broad band on each side of the inferior two-thirds of the anal canal Blends superiorly with the puborectalis muscle Supplied mainly by S4 through the inferior rectal nerve The

An involuntary sphincter Surrounds the superior two- thirds of the anal canal A thickening of the circular muscle layer Innervated by parasympathetic fibers that pass through the pelvic splanchnic nerves Tonically contracted most of the time to prevent leakage of fluid or flatus Relaxes in response to the pressure of feces or gas distending the rectal ampulla Anal canal – parts

Superior derived from the embryonic and inferior derived from the embryonic The (the dentate or mucocutaneous line), an irregular line, indicates the junction of the superior and inferior part, is formed by the inferior comb- shaped limit of the The parts differ in arterial supply, innervation and venous and lymphatic drainage Anal canal – parts

Superior derived from the embryonic hindgut and inferior derived from the embryonic proctodeum The pectinate line (the dentate or mucocutaneous line), an irregular line, indicates the junction of the superior and inferior part, is formed by the inferior comb- shaped limit of the anal valves The parts differ in arterial supply, innervation and venous and lymphatic drainage The inferior part of the anal canal

Anal valves join the inferior ends of the

Anal sinuses- small recesses, superior to the anal valves Arterial supply of the anal canal

The superior rectal artery supplies the superior part of the anal canal The two inferior rectal arteries supply the inferior part of the anal canal The middle rectal arteries form anastomoses with the superior and inferior rectal arteries Venous drainage of the anal canal The internal rectal venous plexus drains in both directions from the level of the pectinate line Superior to the pectinate line the plexus drains chiefly into the superior rectal vein Inferior to the pectinate line the plexus drains into the inferior rectal veins The middle rectal veins mainly form anastomoses with the superior and inferior rectal veins Lymphatic drainage of the anal canal

Superior to the pectinate line the lymphatic vessels drain into the internal iliac lymph nodes and through them into the common iliac and lumbar lymph nodes

Inferior to the pectinate line the lymphatic vessels drain into the superficial Lymphatic drainage Left venous angle Thoracic duct Chyle cistern Right lumbar trunk Intestinal trunks Left lumbar trunk

Right lumbar l.n. Celiac l.n. Left lumbar l.n.

Common iliac l.n. Superior mesenteric l.n. Common iliac l.n

External Internal External Internal

Deep inguinal l.n. Deep inguinal l.n.

Superficial inguinal l.n. Superficial inguinal l.n. Innervation of the anal canal

Superior part- sensitive only to streching, has visceral innervation from the inferior hypogastric plexus (sympathetic and parasympathetic fibers)

Inferior part- sensitive to pain, touch and temperature, has innervation from inferior anal (rectal) nerves, branches of the pudendal nerve The rectouterine pouch

In females the peritoneum reflects from the rectum to the posterior fornix of vagina The rectovesical pouch

In males the peritoneum reflects from the rectum to the posterior wall of the urinary bladder Per rectum- PR THANK YOU!