Download THE ABDOMEN -Located bt thorax and pelvis is surrounded by the

THE ABDOMEN
-Located bt thorax and pelvis is surrounded by the abdominal wall
-Separated from the thorax by the diaphragm
-Continuous inferiorly with the pelvic cavity
-Contains peritoneum, most of digestive organs, including stomach, intestines, gallbladder, liver, pancreas, spleen, kidneys,
adrenal glands, parts of ureters
-Anteriolateral abdominal wall is divided into nine areas by four planes - also divided into four areas by two planes
Right
hypochondriac
Epigastric
Left
hypochondriac
Right lumbar
Umbilical
Left lumbar
Right inguinal
Suprapubic
Left inguinal
Subcostal plane - runs side to side @ 10th costal cartilage (L3)
Transtrabicular plane
Quadrants - medial and Transumbilical plane
RUQ
LUQ
RLQ
LLQ
-Anteriolateral abdominal wall - superiorly, begins @ costal cartilage of 7 - 10, xiphoid process (costal margin)
-Inferiorly, the inguinal ligament and the pelvic bones
-Wall of the anteriolateral abdomen consists of skin, subQ connective tissue, muscles, fascia, peritoneum
-Superficial fascia - subQ - found over most of the AL (anteriolateral) wall, consists of a layer of varying amounts of fat
-Inferior part of the wall - fascia can be divided into two layers
-Camper’s fascia - fatty superficial layer
-Scarper’s fascia - deeper membranous layer
-A firm membranous sheet called the transversalis fascia lines most of the abdominal wall - covers deep surface of the
transversalis abdominus muscles, aponeurosis, is continuous to the linea alba from both sides (down center of AL abdominal
wall)
-Parietal peritoneum is internal to the transversalis fascia, separated from fascia by extraperitoneal fat
Muscles of AL abdominal wall (4)
-3 flat muscles, 1 vertical muscle - direction of the fibers
-All four of them function to compress and support abdominal viscera
-Involved in some trunk flexion
-From most superficial to deep:
1. External oblique - fibers course inferiomedially, interdigitate on lateral sides with the fibers of the serratus anterior
-External surfaces of rib 5 - 12
2. Internal oblique - intermediate (flat) muscle - fibers run @ right angles to the external - superiolateral
-from anterior 2/3rd of iliac crest and lateral half of inguinal ligament  linea alba, inferior border of ribs 10 - 12
3. Transversus abdominus - innermost of the flat muscles - fibers run transverse
-from costal cartilages of 7 - 10
-Most is enclosed in rectus sheath
-Anterior layer of rectus sheath is firmly attached to rectus muscle @ three points:
-Xiphoid
-Umbilicus
-Midway in between xiphoid and umbilicus
-All three muscles end anteriorly in an aponeurosis
-Fibers of aponeurosis - form the sheath of the rectus muscle
-Anterior layer of rectal sheath is formed by the anterior of the
-Posterior layer is formed by the aponeurosis of the interior oblique, transverse abdominus
-Four muscles protect viscera, increase intra-abdominal pressure - important in forced expiration, provides force for
micturition, defecation, parturition
Nerves of the anterior abdominal wall
-Thoracoabdominal intercostal nerves - formed from the ventral rami of T7 - T12 and L1
-Ventral rami of T7 - T9 supply the skin superior to the umbilicus
-T10 is immediately around the umbilicus
-T11, 12, L1 are inferior to the umbilicus
Blood vessels:
-Superior epigastric vessels - arise from the internal thoracic
-Inferior epigastric vessels - arise from the inferior iliac artery
-Inguinal canal - oblique inferiomedially directed canal for passage of spermaticord through inferior part of anterior abdominal
wall
-Lies parallel to and just superior the middle of the inguinal ligament
-Contents - spermaticord in mails, round ligament of the uterus in females
-Ilioinguinal nerves pass through the canal
Inguinal canal - just above inguinal ligament - anterior wall is formed by fibers of the external and internal oblique muscles
-Posterior wall - transversalis fascia, conjoint tendon - formed by fibers from internal oblique, transversalis
-Roof of canal - internal oblique
-Floor is formed by the superior surface of the inguinal ligament and lacuna ligament- extension of inguinal ligament
-Deep inguinal ring - outpouching (bulge) of midpoint of inguinal ligament
Spermatic cord - extends testes and scrotum - contains structures running to and from the testes
-Begins @ deep inguinal ring just lateral to the inferior epigastric artery - passes through inguinal canal and ends on posterior
surface of testes within the scrotum
-Cord is surrounded by fascia from the abdomen - 3 layers
-Internal spermatic fascia - from transversalis fascia
-Cremasteric fascia - from internal oblique - contains fibers that arise from the internal oblique that make up the
cremaster muscle - functionally draw the testes upward within the scrotum (typically in cold temps)
-Contents of the spermatic cord -Ductus (Vas) Deferens
-Testicular artery - arises from abdominal aorta
-Artery for ductus deferens
-Cremasteric artery - arises from the inferior epigastric
-Pampiniform plexus - venous network in the spermatic cord
-Sympathetic fibers on the arteries, both symp and parasymp on vas deferens
-Genital nerves, lymphatic vessels
Scrotum - described as a cutaneous sac consisting of two layers: skin, superficial fascia
-Fascia is devoid of fat, does contain fibers of the dartos muscle - contracts in response to cold temperatures
-Continuous with fascia of anterior abdominal wall, perineum
-Internal pudendal artery, cremasteric, external pudendal
-Genitofemoral nerves (L1, L2), ilioinguinal nerves from L1, branches of the pudenda from S2, 3, 4
Testes - sperm and testosterone production - surface is covered by the tunica vaginalis
-Epididymus is a convoluted duct located on the superior and posteriolateral surfaces of the testes
-Superior part - head of the epididymis
-Efferent ducts transmit sperm from the testes to the epididymis
-Tail of epididymis is continuous with the ductus deferens transmitting sperm to the ejaculatory duct
-Testicular artery arises from the abdominal aorta just below the renal arteries
-Testicular veins join the panpimiform arteries, from which the testicular vein forms
-Autonomic nerves arise from testicular plexus on the testicular artery
-Contains both vagal parasympathetic fibers, sympathetic fibers from T7
Peritoneum
-Defined as a transparent continuous serous membrane that consists of two layers
-Parietal peritoneum - lines abdominal cavity (inferior to transverse abdominal muscle)
-Visceral peritoneum - covers many viscera
-Peritoneal cavity is the space between the two peritoneum - potential space
-Abdominal organs packed very tightly together
-Small amount of serous lubricating fluid is secreted bt the layers to allow for smooth movement
-Peritoneal cavity is closed in males, open in females - through the opening, the uterine tubes, uterus and vagina pass
-Peritoneum and all viscera are within abdominal cavity
-Intraperitoneal organs are the viscera - covered by the visceral peritoneum
-Extraperitoneal (retroperitoneal) organs include kidneys, pancreas, ascending and descending colon - located bt the parietal
peritoneum and posterior abdominal wall
Mesentery - a double layer of peritoneum that begins as an extension of the visceral peritoneum on an organ
-Connects an organ to a body wall
-Have a core of connective tissue - contains blood vessels, lymphatic vessels, nerves
-Viscera with a mesentery are mobile - degree of mobility depends on length of mesentery
Omentum - double layered extension of visceral peritoneum that specifically passes from the stomach to the proximal part of
the duodenum
-Lesser omentum - connects lesser curvature of the stomach, proximal part of duodenum to liver
-Greater omentum - arises from the greater curvature of the stomach, first part of duodenum - descends down and
folds back up to attach to the transverse colon
-Prevents parietal and visceral peritoneum from adhering to each other
-Several ligaments associated with peritoneum and viscera:
-Falciform ligament - connects liver to the anterior abdominal wall
-Stomach is connected to inferior surface of the diaphragm by the gastrophrenic ligament
-Stomach is connected to spleen by gastrosplenic ligament
-Stomach connected to transverse colon by gastrocolic ligament
Principle viscera of the abdomen
-Esophagus, stomach, small intestine, large intestine, spleen, liver, biliary tree, gallbladder, portal vein, renal fascia, kidneys,
ureters, suprarenal/adrenal glands
-*Arterial supply to the viscera via three main branches of the abdominal aorta:
-Ciliac trunk, superior and inferior mesenteric artery
-Foregut
Midgut
Hindgut
-Ciliac trunk is a singular vessel that comes off the abdominal aorta - immediately branches into three major vessels
-Ciliac - splenic, gastric, hepatic arteries
-Portal vein - main channel of portal system of veins - collects blood from abdominal part of GI tract, gall bladder, pancreas,
spleen - carries the blood to the liver
Esophagus
- Muscular tube - 25 cm long
-Runs from the pharynx to the stomach
-Follows the curvature of the vertebral column as it descends through the neck and posterior mediastinum
-Pierces the diaphragm just to the left of the median plane
-Enters the cardia region of the stomach (most superior region of the stomach)
-Level of the 7th costal cartilage or the level of T10
-Distally, the esophagus is surrounded by an esophageal plexus of nerves
-Covered anteriorly and laterally by peritoneum in the abdominal cavity (not thorax)
-However, the esophagus is retroperitoneal
- Arterial supply - gastric branch of celiac trunk, inferior phrenic artery under the diaphragm
- Venous drainage of the esophagus via the left gastric vein which enters the azygos vein
- Innervation of the esophagus via vagal trunks
- Anterior and posterior gastric nerve parasympathetically
- Thoracic sympathetic trunks innvervate the esophagus - greater and lesser splanchnic nerves
THE STOMACH
-The greater curvature - the much larger convex border
-Sharp indentation about 2/3rds of the way down on the lesser curvature, which is called the angular notch
-Marks the junction bt the body of the stomach and the pyloric (distal) part of stomach
-Cardia region is right around opening for the esophagus
-Fundus of the stomach - described as a dilated region on the superior part of the stomach that is in close approximation to
the dome of the diaphragm
-Body: in between the fundus and the pyloric region
-Pyloric sphincter - thickened band of muscle - controls discharge of the stomach contents into duodenum
-Stomach is covered by peritoneum except in the back of the cardia portion, along the curvatures where some vessels are
located
-The anterior surface of the stomach is in contact with the diaphragm, the left lobe of the liver, anterior abdominal wall
-The stomach bed is formed by the posterior wall of the omental bursa and the structures bt the omental bursa and the
posterior abdominal wall
-Include: the diaphragm (comes down, stomach as we lie supine rests on the dome), the transverse colon, pancreas,
spleen, ciliac trunk and its three branches, left adrenal gland, left kidney
-Gastric arteries arise from the ciliac trunk
-Major divisions of the ciliac trunk associated with stomach: left gastric, right gastric artery, right and left gastro-omental
arteries
-Gastroomental vessel = epiploic
-Gastric veins parallel the arteries - drainage of these veins is of significance:
-L and R gastric veins drain into the portal vein
-L and R gastroomental (epiploic) veins drain into the splenic vein, which joins the superior mesenteric vein to form
the portal vein
The small intestine
-Extends from the pyloric sphincter to ileocecal junction
-Three sections: the duodenum, the jejunum, and the ileum
-Only one valve in the system: ileocecal valve bt the ileum and the cecum
-The duodenum - shortest, widest, and most fixed portion of the SI
-Follows a "C-shaped" course around the pancreas
-Begins at the pylorus on the right side and ends at the duodenojejunal junction (left side)
-Divided into four parts:
-Superior part - short (5cm), anteriolateral to the body of L1
-Descending part - 10 cm - descends along the right side of L1,L2,L3
-Horizontal part - 8 cm in length and crosses L3
-Ascending part - 5 cm - begins to the left of L3 and rises to the superior border of L2
-The first 2cm of the duodenum is referred to as the duodenal cap
-Has mesentery and is mobile - receiving discharge from antrum of the stomach (squeezes chyme into duodenum)
-Rest of the duodenum is NOT mobile and is retroperitoneal
-Common bile duct, pancreatic duct enter the duodenum as one duct - hepatopancreatic duct @ its posteriomedial wall
-Enter @ junction of superior and center part
-Where they join is called the hepatopancreatic ampula (slight swelling), which then enters the duodenum
-Site of Endoscopic Retrograde Cholangio Pancreatography
-Duodenum joins the jejunum @ the duodenojejunal flexure
-Supported by a fibromuscular band called the suspensory ligament of the duodenum (ligament of Trietz)
-Contraction of the fibromuscular band facilitates movement of its content through the lumen
Arterierial Supply:
-Superior and inferior pancreatoduodenal arteries supply the duodenum
-Duodenal veins (sup and inf pancreatoduodenal) drain into the portal vein
-Supplied by parasympathetic (vagus) and sympathetic nerves
-Sympathethic nerves come off a plexus that run along the arteries
-*95% of duodenal ulcers occur in the superior part of the duodenum (where duodenum receives chyme)
-If the ulcer perforates the duodenal wall, its contents enter the peritoneal space  peritonitis
-Gallbladder and liver may be affected by a duodenal ulcer because of proximity
-Erosion of the gastroduodenal artery may cause hemorrhage into the peritoneal cavity
-Jejunum - begins duodenojejunal flexture (ligament of Trietz), and the ileum ends at the ileocecal junction
-Together, they are 6-7 meters in length - 40% jejunum, 60% ileum
-Most of the jejunum is the umbilical region, most of the ileum is in the suprapubic and right inguinal region
-No clear demarcation between the jejunum and ileum
-Extensive mesentery associated - attaches most of the SI to the posterior abd wall
-Superior mesenteric artery supply the jejunum and ileum
-Veins of the same name drain the jejunum and ileum
-Sympathetic nerves from T5-T9 innvervate the jejunum and ileum, parasympathetic innvervation is from the vagus nerve
-Nerves from T5 and T9 enter the ciliac plexus
-Sympathetic innveration decreases motility, secretions, and causes vasoconstriction
-Very strong sympathetic innervation can shut GI tract down completely
-Parasympathetic innervation increases motility, secretions, and causes vasodilation.
-The SI is insensitive to most pain stimuli, including cutting and burning
-Sensitive to distention
-Occlusion of the Vasa Recta (branch of the SMA) to the SI results in ischemia to the affected part of the intestine - if
obstruction is severe, necrosis can occur
-Ileus - severe pain usually accompanied by vomiting, fever, dehydration - if early dx, then obstructed vessels can be cleared
-Dx via arteriogram in SMA
The Large Intestine
-Consists of the cecum, appendix (vermiform appendix), colon, rectum, anal canal
-Distinct anatomical differences between the SI and LI
-LI has three thick bands of regionalized muscle around it - tenae coli
-LI has sacculations or segments
-Bt the tenae coli, the sacculations are referred to as haustra
-LI has small pouches of omentum, filled with fat  mental (epiploic) appendages
-Cecum - first part of the LI, distal to ileocecal valve, is continuous with ascending colon
-Located in the RLQ of the abdomen, runs along the right iliac fossa
-Ileum invaginates the cecum to form the ileocecal valve
- The cecum is supplied by the ileocolic artery, which is a branch of the SMA (superior mesenteric artery). Nerve supply to the
cecum and appendix is from a plexus that arises off of the SMA.
The appendix is functionally useless.
-Blind tube that joins the cecum inferior to the ileocecal junction
-Has small mesentery called the mesoappendix - suspends the appendix from the mesentery of the terminal part of the ileum
-Appendix is almost always retrocecal
-Base of the appendix lies deep to McBurney's point
-McBurney's point is @1/3 along an oblique line joining the anterior superior iliac spine and umbilicus
-Arterial supply is via the appendicular artery, a branch of the ileocolic artery - branch of SMA
-Receives both sympathetic and parasympathetic innervation from superior mesenteric plexus
-Acute inflamation of the appendix results in acute abd. pain - digital pressure over McBurney's point registers the area of
max tenderness
-Usually caused by obstruction (fecal matter) - prevents the appendix from draining its secretions
-Appendix swells and stretches the visceral peritoneum
-Pain of appendicitis starts as dull periumbilical pain - afferent nerve fibers enter the spinal cord around T10
-As condition progresses, pain moves to lower quadrant - caused by irritation of parietal peritoneum
-Thrombosis in appendicular artery frequently will result in perforation of an acutely inflamed appendix
The Colon
-Ascending colon travels superiorly from the cecum (right side) up to the liver where it turns towards the left  becomes
transverse colon
-Point of transition: Right Colic Flexure or the Hepatic Flexure
-Ascending colon is retroperitoneal, supplied by branches of the SMA
-The transverse colon is the most mobile and largest part of the LI
-Crosses the abd from the right colic flexure (hepatic flexure) to the left colic flexure (splenic flexure) - turns inferiorly to
become the descending colon
-Left colic flexure lies on inferior part of left kidney
-Attached to the diaphragm by the phrenocolic ligament
-Transverse mesocolon is the mobile mesentery of the transverse colon
-Because the transverse colon is motive, it usually hangs at the level of the umbilicus
-Arterial supply is via colic artery - branch of the SMA
-Receives symp and parasymp innervation
-Descending colon descends retroperitoneally from left colic flexure (splenic flexure) into the left iliac fossa where it is
continuous with the sigmoid colon
-Descends next to the lateral border of the left kidney
-Sigmoid colon is an "S-shaped" loop - links descending colon to the rectum
-Termination of tenae colli indicate the beginning of the rectum
-Rectosigmoid junction is about 15cm from the anus
-Has considerable movement
-Has its own mesentery - sigmoid mesocolon
-Sigmoid colon has both sympathetic and parasympathetic innvervation
-Left colic and superior sigmoid artery (branches of the IMA) supply the sigmoid colon
For test, make sure you know "The descending colon is always ass-ending"
The Spleen
-Largest lymphatic organ, located in the LUQ
-It's diaphragmatic surface is convexly curved to fit the curve of the diaphragm
-Normally contains a large volume of blood - expelled into the circulation periodically by the action of smooth muscle
-*Attached to the stomach by gastrosplenic ligament, attached to the left kidney by the splenorenal ligament
-Except at its hilum, where the splenic artery enters and splenic veins leave, the spleen is enclosed in peritoneum
-Hilum of the spleen is close to the tail of the pancreas
-Splenic artery - largest division of the celiac trunk - divides into five branches as it enters the hilum
-Splenic vein (exits through hilum) - units w/superior mesenteric vein  portal vein
-Spleen is often injured and bleeds profusely - capsule is thin, and its parenchyma ("the meat") is soft and spongy
-Rupture of the spleen causes intraperitoneal hemorrhaging  shock
-Repair of the spleen is not possible, it is removed when injured to prevent massive blood loss and death
The Pancreas
-Elongated digestive and endocrine organ that lies transversly across the abdomen, posterior to the stomach, posterior to the
abdominal wall
-Both endocrine and exocrine organ - s&s insulin, glucagon, exocrine - produces digestive enzymes
-Head of the pancreas lies in the curve of the duodenum
-Has an extension (prolongation) - uncinate process  lies posterior to the superior mesenteric vessels
-Lies on the IVC, the right renal artery and vein, and the left renal vein
-The common bile duct lies in a groove on the posterior superior head of the pancreas
-The neck of the pancreas is right next to the pyloric sphincter
-The body of the pancreas extends over to the left across the aorta and vertebrae L2
-The anterior surface is covered with peritoneum and forms part of the bed of the stomach
-The posterior surface has NO peritoneum and is in contact with the aorta, superior mesenteric artery, left kidney, left
adrenal gland, renal vessels
-The tail of the pancreas passes bt layers of the splenorenal ligament, contacts the hilum of the spleen
The pancreatic duct
-Begins @ tail of the pancreas, runs through the entire gland  turns inferiorly and comes in contact with common bile duct
-Where pancreatic duct and CBD unite -- ampulla  opens into duodenum
-Sphincter @ end of the pancreatic duct (pancreatic duct sphincter) just prior to it joining the common bile duct
-Sphincter on the hepatopancreatic duct - sphincter of Oddi, which is located just before the entrance to the duodenum (after
they unite)
-Essential that pancreatic juice secretion is controlled as it goes into the SI
-In about 9-10% of the population, there is an accessory pancreatic duct which arises from the uncinate process
-Drains directly into the duodenum
-Pancreas has a very rich blood supply via divisions of the splenic artery, branches of the gastroduodenal artery
Surface anatomy
-The spleen lies on the left side of the abd. between ribs 9-11
-Rests on the left colic flexure (where the transverse colon becomes the descending colon)
-Tail of pancreas is in contact w/hilum of the spleen
-Body of the pancreas lies at a level bt T12, L2
The Liver
-Largest gland in the body
-Extensive ligament network involving triangular and corollary ligaments to support the liver
-Lies almost entirely in the right upper quadrant where part of it is protected by the thoracic cage
-Drops somewhat inferiorly when you stand
-Pyramidal in shape: base to the right, apex to the left
-In supine position, it extends inferiorly to the right costal margin
-Easily palpated when the individual being examined inspires deeply due to inferior mov‘t of diaphragm
-In addition to many metabolic functions, the liver stores glycogen and S&S's bile
-Bile from the liver passes through the hepatic duct into the cystic duct - bile is concentrated by reabsorption of water
-The diaphragmatic surface is smooth and dome shaped - conforms to the concavity of the diaphragm
-Separated from the diaphragm by the subphrenic recess (invagination of peritoneum)
-Covered by peritoneum, except on its posterior superior surface in bare region - direct contact w/diaphragm
-Surrounded by the anterior (upper) and posterior (lower) coronary ligaments
-Merge to form the right triangular ligament
-Anterior layer of the coronary ligament is continuous on the left with the right layer of the falciform ligament
-Posterior layer of the coronary ligament is continuous with the lesser omentum
-The right layer of the falciform ligament and the lesser omentum meet to form the left triangular ligament
-Visceral surface of the liver - covered with peritoneum except @ gall bladder and the Porta Hepatis (opening in liver)
-In contact w/right side of the stomach, superior part of the duodenum, gallbladder, the right colic flexure, right kidney and
adrenal gland
-Hepatorenal recess is space bt visceral surface of right lobe of liver, right kidney
-The liver is divided into functionally independent right and left lobes
-Each lobe has its own blood supply from the hepatic artery and portal vein, + venous and biliary drainage
-Right and left lobes of the liver are separated by the gall bladder fossa.
-The IVC runs along right next to the gallbladder
-The left lobe of the liver further divided: the caudate lobe and most of the quadrate lobe
-The lesser omentum encloses the portal triad (portal vein, bile duct, and hepatic artery) @ the porta hepatis or hilum of liver
-The part of the lesser omentum between the liver and the stomach - hepatogastric ligament
-The part of the lesser omentum that attaches the liver to the duodenum - hepatoduodenal ligament
-The liver receives blood from two sources: hepatic artery and the portal vein
-70% from portal vein, 30% from hepatic artery
-Hepatic artery delivers oxygen rich blood from aorta to the liver
-Portal vein delivers oxygen deficient blood to the liver from the GI tract
-Horizontal plane through the liver divides it into 8 vascular segments
-Hepatic veins drain these segments
-Open into the IVC just inferior to the diaphragm
-Attachment of veins to IVC also helps to support the liver
-Nerves associated w/liver are from the hepatic plexus - derivative of ciliac plexus - both symp and parasymp fibers
The biliary ducts and the gallbladder
-Bile is S&S by hepatocytes (liver cells), drained into R and L hepatic ducts  leave the liver through the porta hepatis
-Unite to form the common hepatic duct
-Common hepatic duct joins with the cystic duct on the right from the gallbladder to form the common bile duct
-CBD (lies posterior to the head of the pancreas) to deliver bile to the superior part of the duodenum
-CBD + pancreatic duct = hepatopancreatic duct prior to entering the duodenum
-@ distal end of CBD, before it unites w/pancreatic duct - thickened band of muscles called the choledochal sphincter
-When sphincter is in closed position, bile backs up to the gallbladder where the bile is concentrated
-CBD has extensive arterial supply via the cystic artery, right hepatic artery, pancreaduodenal artery, gastroduodenal artery
-Veins of similar names drain blood
-The gallbladder lies in the gallbladder fossa - visceral surface of the liver
-Peritoneum holds body of gallbladder to the liver
-Parts of gallbladder:
-Fundus - wide end, located @ tip of 9th costal cartilage, midclavicular line
-Body - in contact w/visceral surface of the liver, transverse colon, superior part of the duodenum
-Neck - narrow part (where stones are lodged) - pointed toward the porta hepatis - joints the cystic duct
-Mucosa over the neck of the gallbladder is shaped into a spiral valve - keeps the cystic duct open
-Cystic artery supplies the cystic duct and gallbladder
The Portal System
-The portal vein is the main channel for the portal system of veins
-Collects blood from the abd. part of the GI tract (gallbladder, pancreas, spleen), carries it to the liver
-*Portal venous system communicates w/systemic venous system in the following way:
1. Left gastric vein and the esophageal vein (portal system) communicate w/azygous vein (systemic)
2. Inferior and middle rectal veins (systemic) communicate w/ the inferior mesenteric vein (portal)
-The portal-systemic anastomoses is important - when portal system is obstructed, as in liver disease, blood can still reach
the right side of the heart through the IVC
-This connection works bc the portal vein and its tributaries have NO valves
-Allows for blood to flow in either direction
The Kidneys
-Retroperitoneal, located on posterior to the abdominal wall from T12-L3
-Right kidney being slightly lower because of the size of the liver
-Each kidney has anterior and posterior surface, lateral margin, superior and inferior pole
-Superiorly, each kidney is next to diaphragm and Rib 12
-Inferiorly is in contact with the quadratus lumborum muscle
-Subcostal vessels and ileohypogastric and ileoinguinal nerves pass right over the back surface of the kidney
-Liver, duodenum, and ascending colon are anterior to right kidney
-Left kidney is right next to stomach, spleen, and pancreas, small parts of the jejunum and descending colon
-Medial surface of each kidney is hilum - opening for renal artery, renal nerves, renal vein, ureter
-Hilum leads into the renal sinus
-Renal fascia - fibrous tissue that surrounds the kidney
-Separated from capsule of the kidney by a layer of of fat - perirenal fat
-Continuous w/fat in renal sinus
-External to the renal fascia is pararenal fat
-Renal fascia sends collagen fibers through the fat to help hold the renal vessels and ureters as well as kidneys
themselves in position
-Renal ptosis - kidneys slip out of place, bend the ureters
-Ascends to the suprarenal (adrenal) glands
-Attachment of the renal fascia is important in preventing the spread of exudate (pus) if there is a perinephric
abscess
-Within the sinuses of the kidneys are the calices, renal vessels, renal nerves
Ureters of the kidneys
-Muscular ducts with a narrow lumen
-Carry urine from kidney to urinary bladder
-Expanded end of the ureter = renal pelvis - located in the sinus of each kidney
-Each ureter divides into two or three major calices - further divide into minor calices - each of the minor calices drain from
apex of the renal pyramid
-(each papilla from kidney drain into minor calyx - several minor calices unite to form a major calyx - major calices unite to
form renal pelvis = expanded end of the ureter)
-Abdominal part adheres to the parietal peritoneum - retroperitoneal
-Run inferiomedially along the transverse processes of the lumbar vertebrae - each cross the external lumbar arteries just
inferior where the iliac arteries bifurcate
The adrenal glands
-Lie on the superiomedial border of each kidney
-Each gland is enclosed by the renal fascia - holds them in close approximation
-R adrenal gland is triangular in shape, anterior to the diaphragm
-Makes contact with the IVC laterally and with the liver
-L adrenal gland is semilunar in shape and is in contact with the spleen, stomach, pancreas, and diaphragm
-Renal arteries arise off abdominal aorta almost as soon as aorta pierces the diaphragm
-(Kidney is most active tissue metabolically than any other tissue - receive 20-25% of cardiac output at rest)
-Each renal artery enters the hilum and divides into five segmental arteries
-R renal artery is lower than the left (liver is on the right) - right renal vein lower than left renal vein
-Each renal vein drains into the IVC
-Adrenal glands have a profuse blood supply from three sources:
1) Superior suprarenal arteries  arise off the inferior phrenic arteries
2) Middle suprarenal arteries  arise off the abdominal aorta
3) Inferior suprarenal arteries  arise off renal arteries
-Each gland is drained by a suprarenal vein
-Arteries for abdominal part of the ureters are from renal arteries, testicular(/ovarian) arteries, abdominal aorta
-Nerves to the adrenal gland are from the renal plexus - consist of both sympathetic and parasympathetic fibers
The diaphragm (thoracic diaphragm)
-Musculotendinous partition - separates the abdominal and thoracic cavities
-Principle muscle of resting inspiration, forms convex floor of the thorax, concave roof of the abdomen
-Only the domes of the diaphragm move during inspiration
-Peripheral parts of the diaphragm are attached to the inferior thoracic cage, lumbar vertebrae
-Right dome of the diaphragm is higher than the left (liver on right side)
-Levels of the domes change based on posture, phase of the respiratory cycle
-Composed of a peripheral muscular part and a central apneustic part (central tendon)
-The muscle fibers of the diaphragm radiate inward toward the central tendon
-Divided into three sections:
1) Sternal part - attached to the posterior xiphoid
2) Costal part - attached to the inferior 6 ribs
3) Lumbar part - attached to the lumbar vertebrae
-Central tendon is the tendon of all of the muscle fibers of the diaphragm - fused with the inferior surface of
the fibrous pericardium
-Has NO bony attachments
-Diaphragmatic apertures - openings allowing structures to pass from thorax to abdomen
-Venacavoforamen - allows IVC to pass through as it ascends
-Located within the central tendon of the diaphragm bt T8 and T9
-IVC is attached to the edge of the foramen - when diaphragm contracts, the venacavoforamen enlarges
-Facilitates venous return
-Esophageal hiatus - aperture in the right dome of the diaphragm (T10) for the esophagus
-Right crus is a region of the diaphragm where there are muscle fibers  esophagus is constricted when
muscle contracts (@ inspiration)
-Vagal trunks, gastric vessels also pass through
-Aortic hiatus - behind the diaphragm - blood flow is NOT affected by breathing
-Thoracic duct and azygous vein also pass through the aortic hiatus
Posterior abdominal wall
-Composed mostly of muscle and fascia attached to the vertebrae, hip bones, ribs
-PAW also contains fat, nerves, lymph, blood vessels
-Three paired muscles:
-Psoas major - runs from transverse process of the lumbar vertebrae to lesser trochanter of the femur
-Hip flexor
-Quadratus lumborum (back ache) - runs from lumbar vertebrae to iliac crest
-Extends and laterally flexes the vertebral column
-Iliacus - runs from inferior 2/3rds of iliac fossa to lesser trochanter
-Flexor @ hip joint
-PAW is covered with a continuous layer of fascia that lies bt the peritoneum and those three muscles
-Fascia take name of muscles (quadratus lumborum fascia, iliac fascia, etc)
-Subcostal nerves  arise from ventral rami of T12 - supply muscles and skin of anteriolateral abd wall supply
-Lumbar nerves supply muscles of the skin and back (dorsal rami)
-Lumbar plexus - located in psoas muscles - formed from the ventral rami of L1-L4**
-Major nerves: Obturator formed from the ventral rami of L2, 3, 4 - innervates the medial ADDuctor thigh muscles
-Femoral - L2, 3, 4 - innervates the extensors at the knee (anterior/quadriceps)
-Lumbrosacral trunk from L4-L5 - descend into pelvis to participate in the formation of the sacral plexus
(along with ventral rami of S1-S4)
-Both sympathetic and parasymp nerves are distributed to the abdominal viscera by ganglia located on the anterior surface of
the abdominal aorta
-Sympathetic portions = splanchnic nerves
-Parasympathetic portions = vagal
-Vessels of the posterior abdominal wall are primarily branches of the abdominal aorta
-Runs from T12 to L4 - @ L4, bifurcates to form the common iliac arteries
-Arterial branches off the abdominal aorta are either parietel or visceral and paired or unpaired
-Unpaired visceral vessels: celiac trunk, superior and inferior mesenteric arteries
-Paired visceral: renal arteries, suprarenal arteries, gonadal arteries
-Paired parietal: lumbar arteries, subcostal arteries, and inferior phrenic
-Unpaired parietal: median sacral artery  arises off abdominal aorta @ point where it splits into common iliac
-Veins of the posterior abdominal wall are tributaries of the IVC
-Except gonadal veins - enter the renal veins before IVC
-Several collateral roots for venous return if IVC is obstructed
-Venous return through lateral thoracic veins - connect w/circumflex iliac veins, then axillary vein
-Lymphatics run along IVC aorta and iliac vessels
-Common iliac lymph nodes receive lymph from lower limbs, pass lymph to lumbar lymph nodes
-Lymph from GI tract, liver, spleen pancreas drain into preaortic lymph nodes - located along aorta where arteries arise
-Lumbar lymph nodes receive lymph from the iliac, posterior abdominal wall, kidneys, ureters, gonads, uterus, uterine tubes,
descending colon, areas within the pelvis
-Drain into the cisterna chili - thin walled sac at the inferior end of the thoracic duct
-Located just in front of bodies of L1, L2
-Thoracic duct - ascends through the aortic hiatus to thorax- behind the diaphragm
-Receives ALL lymph from areas of the body inferior to the diaphragm and returns the lymph to the vascular system at the
junction of the left subclavian vein and the left internal jugular vein
-Also returns lymph from the left half of the torso, head, upper limb (75%)
-25% through R. Lymphatic duct