Surface Topography of the Abdomen

The Abdomen

Surface Topography of the Abdomen:

Quadrants and Their Contents: Divided by Transumbilical plane (L3/L4) and Median Plane Intersection

Right Upper Quadrant: liver and gallbladder Left Upper Quadrant: stomach and spleen Right Lower Quadrant: cecum and appendix (at Left Lower Quadrant: descending colon and McBurney’s Point between ASIS and umbilicus) sigmoid colon

Nine Region Pattern: Intersections of 2 Midclavicular Planes, Subcostal Plane (below costal cartilage of rib 10), and Intertubercular Plane (tubercles of iliac crests)

Right Hypochondrium Epigastric Left Hypochondrium Right Flank Umbilical Left Flank Right Groin (Inguinal) Pubic Left Groin (Inguinal)

Gut Derivatives:

Primitive Gut Region Adult Gut Region Supplying Artery/Lymphatics/ Innervations/ and Referred Pain Distal esophagus, stomach, Celiac Foregut proximal duodenum, liver, Epigastric region pancreas, and gallbladder Parasympathetic: Vagus Nerve Celiac Pre-aortic nodes Distal duodenum, jejunum, Superior Mesenteric ileum, cecum, appendix, Umbilical region Midgut ascending colon, and proximal Parasympathetic: Vagus Nerve 2/3 of transverse colon Superior mesenteric Pre-aortic nodes Inferior Mesenteric Distal 1/3 of transverse colon, Pubic region Hindgut descending colon, sigmoid colon, Parasympathetic: Pelvic rectum, and upper anal canal Splanchnic Nerves Inferior mesenteric Pre-aortic nodes

Skeletal Components of the Abdominal Wall

- 5 lumbar vertebrae and their intervertebral discs

- Superior expanded parts of pelvic bones

- Inferior thoracic wall: costal margin, rib 12 and end of rib 11, and the xiphoid process Muscles of the Abdominal Wall

Muscle Attachment Innervation Action Transverse processes of L5, iliolumbar ligament, and iliac Anterior rami of Depress and stabilize rib Quadrates lumborum crest to transverse processes T12 and L1 to L4 12 and some lateral of L1 to L4 and inferior border bending of trunk of rib 12 Bodies and intervertebral discs Psoas major of T12-L5, transverse processes Anterior rami of Flex thigh at hip of L1-5 to lesser trochanter of L1 to L3 femur Bodies and intervertebral discs Psoas minor of T12 and L1 to pectineal line Anterior rami of Weak flexion of lumbar of pelvic brim and iliopubic L1 vertebral column eminence Iliac fossa, anterior sacroiliac Iliacus and iliolumbar ligaments, and Femoral Nerve upper lateral sacrum to lesser (L2 to L4) Flexion of thigh at hip trochanter of femur Thoracolumbar fascia, iliac crest, lateral 1/3 inguinal Transversus abdominis ligament, costal cartilages of Anterior rami of Compress abdominal ribs 7-12 to linea alba, pubic T7 to T12 and L1 contents crest, and pectineal line Thoracolumbar fascia, iliac Compress abdominal crest, and lateral 2/3 inguinal contents, bilaterally flex Internal oblique ligament to inferior border of Anterior rami of trunk, unilaterally bend lower 3 ribs, linea alba, pubic T7 to T12 and L1 trunk to same side and crest, and Pectineal line turn anterior part of abdomen to same side Compress abdominal contents, bilaterally flex External oblique Outer surface of ribs 5-12 to Anterior rami of trunk, unilaterally bend lateral lip of iliac crest and T7 to T12 trunk to same side and linea alba turn anterior part of abdomen to same side Pubic crest, pubic tubercle, Compress abdominal Rectus abdominis and pubic symphysis to costal Anterior rami of contents, flex vertebral cartilages of ribs 5-7 and the T7 to T12 column, and tense xiphoid process abdominal wall Pyramidalis Front of pubis and pubic Anterior ramus Tenses the linea alba symphysis to linea alba of T12 Ligaments of the Abdomen

Ligament Attachments Significance Inguinal Ligament ASIS and Pubic Tubercle Formation of inguinal canal Lacunar Ligament Extends from medial inguinal ligament that pass backward to attach to pecten pubis Pectineal (Cooper’s) Ligament From lacunar ligament to pecten pubis of pelvic brim

Major Arteries of the Abdomen

Artery Branches From Supplies Significance Celiac Anterior Aorta at L1 Foregut Superior mesenteric Anterior Aorta at L2 Midgut Inferior mesenteric Anterior Aorta at L3 Hindgut Anastomoses with right Left Gastric Celiac Trunk (smallest Abdominal esophagus gastric a. and branch) and surfaces of stomach esophageal branches from thoracic aorta Spleen, neck/body/tail Gives off left gastro- Splenic Artery Celiac Trunk (largest of pancreas, fundus of omental a. that branch) stomach (short gastric anastomoses with the arteries) right gastro-omental a. Divides into Hepatic artery proper (right Liver, pancreas, (gives of cystic a.) and Celiac Trunk (medium gallbladder, surface of left hepatic aa.) and Common Hepatic Artery size branch) stomach and greater Gastroduodenal artery omentum (right gastro- (to the right gastro- omental a.), duodenum omental and posterior and anterior superior pancreaticoduodenal aa.) Splits into anterior and Inferior Head and uncinate posterior inferior p-d aa Pancreaticoduodenal a. Superior Mesenteric process of the pancreas that anastomose with Artery and the duodenum the anterior and post superior p-d aa. Pass between 2 layers of mesentery and form Superior Mesenteric anastomosing arches Jejunal and Ileal Artery (left side) Jejunum and ileum and the vasa recta that Arteries give the final direct supply to the walls of the small intestine Middle Colic Artery Superior Mesenteric Transverse colon Enters the transverse Artery (1st branch from mesocolon and right side) branches to right and left middle colic aa. Superior Mesenteric Anastomoses with Right Colic Artery Artery (2nd branch from Ascending colon ileocolic and middle right side) colic aa. Divides into superior (anastomose with right Superior Mesenteric Ascending colon, colic a.) and inferior Ileocolic Artery Artery (3rd branch from cecum, appendix, and (colic, cecal, right side) final portion of ileum appendicular, and ileal branches) branches. Upper descending colon Divides into ascending Inferior Mesenteric and distal transverse and descending Left Colic Artery Artery (1st branch) colon (ascending), branches and lower descending colon anastomoses with 1st (descending) sigmoid artery Inferior Mesenteric Lower descending colon Anastomoses with left Sigmoid Arteries Artery (2 to 4 branches) and sigmoid colon colic a. and superior rectal artery branches Inferior Mesenteric Rectum and internal Anastomose with Superior Rectal Artery Artery (terminal branch) anal sphincter middle rectal aa. And inferior rectal aa. Musculophrenic artery Internal thoracic artery Superficial Superior abdominal wall Superficial epigastric Superficial and inferior and Superficial Femoral artery Superficial Inferior epigastric arteries enter circumflex iliac artery abdominal wall rectus sheath and anastomose Superior Epigastric Internal thoracic artery Deep superior artery abdominal wall 10th and 11th intercostal Deep lateral abdominal arteries and subcostal wall artery Inferior epigastric artery Superficial and inferior and deep circumflex External iliac artery Deep inferior epigastric arteries enter iliac artery abdominal wall rectus sheath and anastomose

Major Veins of the Abdomen

Vein Tributaries Drains Significance Formed by splenic and superior mesenteric Spleen, pancreas, Hepatic portal system. Portal Vein veins (at level of L2). gallbladder, abdominal Its right and left Right and left gastric part of GI tract branches enter the veins (lesser curvature liver. of stomach and esophagus), cystic veins gallbladder), para- umbilical veins (ab wall) Short gastric veins, left gastro-omental vein, Spleen, greater Splenic Vein pancreatic veins, curvature of stomach Hepatic portal system inferior mesenteric vein Jejunal, ileal, ileocolic, right colic, middle colic, right gastro-omental, Small intestine, cecum, Superior Mesenteric and anterior and ascending colon, and Hepatic portal system Vein posterior inferior transverse colon pancreaticoduodenal veins Inferior Mesenteric Superior rectal vein, Rectum, sigmoid colon, Vein sigmoid veins, and left descending colon, and Hepatic portal system colic vein splenic flexure

Lymphatic Drainage of the Abdomen:

- Superficial drainage to axillary nodes (above umbilicus) and superficial inguinal nodes (below umbilicus)

- Deep drainage to parasternal nodes(along internal thoracic artery), lumbar nodes (along aorta), and external iliac nodes (along external iliac artery)

- Pre-aortic nodes (celiac, superior and inferior mesenteric) drain gut (GI tract, liver, gallbladder, pancreas, and spleen)

- Para-aortic nodes (right and left lateral aortic or lumbar nodes) drain the body wall, kidneys, suprarenal glands, and the gonads

- Right and Left Subclavian trunks: upper abdominal wall

- Thoracic Duct: abdominal walls and viscera

Canals and Compartments

Canal/Compartment Borders Contents Begins with deep inguinal ring and ends Spermatic cord in men and the with superficial inguinal ring. Aponeurosis round ligament of uterus and of external oblique (anterior wall), genital branch of genitofemoral Inguinal Canal transversalis fascia (posterior wall), nerve (L1/L2) in women transversus abdominis and internal oblique (roof), and inguinal ligament (floor) External spermatic fascia (aponeurosis of Ductus deferens, artery to ductus external oblique), cremasteric fascia deferens, testicular artery (from Spermatic Cord (internal oblique), and internal spermatic aorta), pampiniform vein plexus, fascia (transversalis fascia) cremasteric artery and vein, genital branch of genitofemoral nerve, sympathetic and visceral afferent nerve fibers, lymphatics, and remnants of processus vaginalis

Abdominal Viscera: Intraperitoneal or retroperitoneal

Viscera Location Blood Supply/Nerve Supply

Esophageal branches from left gastric artery (from celiac Esophagus T10 (esophageal hiatus trunk) and esophageal branches from left inferior phrenic through diaphragm) to artery (aorta) (abdominal the cardiac orifice of the part) stomach (left to midline) Anterior vagal trunk (several small trunks, from left vagus nerve) and the Posterior vagal trunk (single trunk from right vagus nerve

Stomach Between the esophagus Left gastric artery (from celiac trunk), right gastric artery and small intestine in the (from hepatic artery proper), right gastro-omental artery (4 regions: epigastric, umbilical, and (from gastroduodenal artery), left gastro-omental artery cardia, fundus, left hypochondriac (from splenic artery), and the posterior gastric artery body, pylorus) regions (from splenic artery)

Duodenum Between stomach and jejunum, C-shaped, 20- Supraduodenal artery, duodenal branches from anterior (4 parts: 1st 25cm long, above the and posterior superior pancreaticoduodenal artery (all superior, 2nd level of the umbilicus, from gastroduodenal artery), the anterior and posterior descending, 3rd adjacent to head of inferior pancreaticoduodenal artery, and first jejuna inferior, 4th pancreas branch (all from superior mesenteric artery) ascending) Between duodenum and Jejunum ileum, the proximal 2/5 of the small intestine, Jejunal arteries from the superior mesenteric artery mostly in the left upper quadrant Between the jejunum and the cecum, the distal Ileal arteries and ileal branch from ileocolic artery (both Ileum 3/5 of the small intestine, from superior mesenteric artery) mostly in right lower quadrant Large Intestine From right groin (as the To cecum and appendix: anterior and posterior cecal cecum) through right arteries and appendicular artery from ileocolic artery (Sections: flank, right (from superior mesenteric artery), to ascending colon: cecum, hypochondrium, crossing superior mesenteric artery branches, to transverse colon: appendix, abdomen to left superior and inferior mesenteric artery branches, to the ascending hypochondrium, descending and sigmoid colons: branches of inferior colon, continuing down to left mesenteric artery, to rectum and anal canal: branches of transverse flank and into left groin inferior mesenteric artery and internal iliac artery colon, descending colon, sigmoid colon, rectum, and anal canal) Liver Primarily in right hypochondrium and (4 lobes: right, epigastric regions, rests Right and Left hepatic arteries from hepatic artery proper left, caudate, under the diaphragm, (from common hepatic artery from celiac trunk) and quadrate) protected by the rib cage Gallbladder Found on the visceral surface of the liver in a (3 parts: fossa between the right Cystic artery from the right hepatic artery (from hepatic fundus, body, and quadrate lobes artery proper) neck) Pancreas Extends across the posterior abdominal wall Gastroduodenal artery, anterior and posterior superior (5 parts: head, from the duodenum to and inferior pancreaticoduodenal arteries, dorsal uncinate the spleen, mostly pancreatic artery, great pancreatic artery, process, neck, posterior to the stomach body, and tail) Lies against diaphragm in the area of rib 9 to 10 in the left upper quadrant, Spleen connected to the Splenic artery from the celiac trunk stomach (by gastrosplenic ligament) and to the left kidney (by the splenorenal ligament) Lie in the posterior extraperitoneal Kidneys connective tissue lateral Renal arteries (2) from lateral abdominal aorta to vertebral column from T11 to L3 Renal arteries, branches from the abdominal aorta , testicular or ovarian arteries, and common and internal iliac arteries Between the kidneys and Ureters the urinary bladder, (Renal, aortic, superior hypogastric, and inferior hypogastric plexuses. Visceral efferents (symp and para) Visceral afferents return to T11-L2 (referred pain to cutaneous areas of T11-L2: post/lat abdominal wall, pubic region, scrotum, labia majora, prox. Ant. Thigh) Suprarenal Superior pole of each Inferior phrenic arteries (branch to superior suprarenal Glands kidney arteries), middle suprarenal arteries, artery, and inferior suprarenal arteries

Peritoneum:

Fold Location Function/Significance Attaches to the greater curvature of the stomach Greater and the first part of the Derived from dorsal mesentery, can migrate to inflamed Omentum duodenum and travels areas of the bowel, important site for tumor spread back upward to attach to posterior abdominal wall Extends from lesser Derived from ventral mesentery, divided into the Lesser curvature of the stomach hepatogastric and hepatoduodenal ligaments (encloses Omentum and first part of the hepatic artery proper, bile duct, and portal vein, and duodenum to the inferior forms anterior border of omental foramen), contains surface of the liver right and left gastric vessels Connects jejunum and ileum to the posterior Mesentery abdominal wall, passes Contains arteries, veins, nerves, and lymphatics that obliquely from supply the jejunum and the ileum duodenojejunal junction to ileocecal junction Transverse Connects transverse colon Contains arteries, veins, nerve, and lymphatics related to Mesocolon to posterior abdominal transverse colon wall Attaches sigmoid colon to abdominal wall, V shaped Sigmoid with the apex near the Contains the sigmoid and superior rectal vessels, along Mesocolon division of the left with nerves and lymphatics associated with the sigmoid common iliac artery into colon internal and external branches

Important Nerve structures and Innervations:

Structure Innervation Referred Pain Parietal Peritoneum Somatic afferents of associated spinal nerves No, well localized Yes, poorly localized Visceral Peritoneum Visceral afferents that accompany autonomic nerves back discomfort and to CNS reflex activity Abdominal GI Tract, Extrinsic: motor impulses from CNS and sensory impulses spleen, pancreas, to CNS (visceral afferents and efferents) Parasympathetic gallbladder, liver from Vagus and Pelvic splanchnics Intrinsic: enteric nervous system (sensory and motor) organized into two plexuses (myenteric and submucosal), Walls of GI tract regulates and controls secretary activities, GI blood flow, and peristalysis. Can be modified by Sympathetics! Sympathetic Trunk:

- Base of skull to coccyx

- Composed of ganglia (neuronal cell bodies) and trunks

- 3 cervical, 11 or 12 thoracic, 4 lumbar, 4 or 5 sacral, and the ganglion impar at the coccyx

- Trunks contain preganglionic and postganglionic sympathetic fibers and visceral afferents

- Gray rami communicantes connect ganglia and trunks to adjacent spinal nerves

- White rami communicantes present from T1 to L2

Splanchnic Nerves:

- Innervate abdominal viscera

- Thoracic, lumbar and sacral splanchnic nerves carry preganglionic sympathetic fibers and visceral afferents

- Pelvic splanchnic nerves carry preganglionic parasympathetic fibers (from S2-4)

- Greater Splanchnic Nerve (Thoracic):T5-9, travels to celiac ganglion

- Lesser Splanchnic Nerve (Thoracic): T10-11, travels to aorticorenal ganglion

- Least Splanchnic Nerve (Thoracic): T12, travels to renal plexus

- Lumbar Splanchnic Nerves (2 to 4 of them) enter the prevertebral plexus (extends from aortic hiatus to right and left common iliac arteries) carrying preganglionic sympathetic fibers and visceral afferents

- Sacral Splanchnic Nerves enter the hypogastric plexus (pelvic plexus)

- Pelvic Splanchnic Nerves: ONLY splanchnics that carry Parasympathetic fibers, originate directly from anterior rami of S2-4, supplies the distal 1/3 colon transverse, descending colon, and sigmoid colon with preganglionic parasympathetic fibers

Abdominal Prevertebral Plexus and Ganglia:

- 3 major divisions: celiac, aortic, and superior hypogastric plexuses

- Receives preganglionic parasympathetic and visceral afferents from Vagus nerve, preganglionic sympathetic and visceral afferents from thoracic and lumbar splanchnic nerves, and preganglionic parasympathetics from the pelvic splanchnic nerves Clinical Correlations:

Clinical Correlate Anatomy Involved Patients Presents W/ Misc. The herniated sac protrudes Most common through the deep inguinal Lump present in the More common in men Indirect Inguinal ring lateral to inf. epigastric scrotum or labia because of their larger Hernia vessels, compressing the majorus inguinal canal structures within the Congenital (processus inguinal canal. vaginalis patent) The herniated sac enters the More common in Direct Inguinal medial end of the inguinal mature men Hernia canal (at the inguinal Lump present in groin Acquired (weak muscles triangle) through a or raised intra- weakened posterior wall abdominal pressure)

Superior part of duodenum, Most common in either anteriorly( erode into Peritonitis and duodenal cap (1st part) peritoneal cavity) or subdiaphragmatic gas posteriorly (erode into (anterior ulcer), or May be due to H. pylori Duodenal Ulcers gastroduodenal or posterior internal bleeding bacteria or excessive superior (posterior ulcer) acid production in pancreaticoduodenal stomach arteries) Remnant of the proximal Bleeding, yolk stalk (vitelline duct) intussusception, Meckel’s that extends into the diverticulitis, ulceration, Occurs in about 2% of Diverticulum umbilical cord and lies on obstruction (symptoms population the antimesenteric border present in small of the ileum number of patients) Vague epigastric pain, Stomach Stomach wall, can be caused early fullness with Carcinoma by gastritis, pernicious eating, bleeding leading Poor survival rates anemia, and polyps to chronic anemia, and obstruction Pain begins as a central periumbilical intermittent pain that develops into constant Requires an Appendicitis appendix localized pain in the appendectomy right groin. May have a temperature, nausea, and vomiting Pancreas, duodenum. Ventral bud of embryologic Poor gastric emptying, Annular Pancreas pancreas splits and the 2 vomiting, Congenital segments encircle the polyhydramnios, failure duodenum to thrive Gallbladder, bile ducts. The Referred pain in skin stones are a mix of over shoulder, jaundice More common in Gallstones cholesterol and bile pigment (bile flow obstructed) women that undergo calcification Excess bilirubin in the blood plasma, can be caused by: conditions involving excessive RBC breakdown Yellow discoloration of Jaundice (hemolytic anemia), the skin (best seen in inflammatory change within sclera of eyes) the liver (hepatitis, cirrhosis), poisons, obstruction of biliary tree (gallstones, tumor)

Rupture: localized trauma to left upper quadrant, left lower rib Huge blood supply to Splenic disorders fractures the spleen: bleeds (rupture and Spleen and its vasculature profusely when enlargement) and lymphatic tissue Enlargement: ruptured lymphadenopathy, leukemia, lymphoma, infections Varicose veins (hemorrhoids, Liver tissue damaged by esophageal varices, and toxins/virus/biliary caput medusa) ), Hepatic Cirrhosis obstruction/ vascular jaundice (buildup of obstruction/ malnutrition/ bilirubin) buildup of and inherited disorders. toxins (leads to Portal hypertension leading neurological to varicose veins symptoms), inadequate blood clotting proteins Diaphragm (central tendon and esophageal hiatus) Diaphragmatic Morgagni’s: between Abdominal contents Hernia: xiphoid process and costal (bowel) enters the Morgagni’s and margins on the right thoracic cavity and Bochdalek’s most Bochdalek’s: on left where reduces respiratory common the pleuroperitoneal function membrane fails to close the pleuroperitoneal canal Acid reflux, pain in Hiatus Hernia Diaphragm, esophagus, epigastric region, Very common, about fundus of stomach ulceration leading to 20% of population bleeding and anemia Can become lodged at the 3 constricted points Kidney Stones Pain in infrascapular of the ureters: Kidney tissue, precipitates of region into the groin, ureteropelvic junction, calcium, phosphate, oxalate, and possibly in scrotum pelvic brim (where they More common in urate, and other salts or labia majora, blood cross the common iliac Men in urine vessels), and their entrance into the bladder wall Arises near intervertebral discs, some infections like Psoas sheath most Psoas muscle tuberculosis and salmonella Mass below inguinal important out of any abscess discitis spread ant/lat and ligament muscle sheath infection seeps into the psoas muscle and its sheath