ANATOMY- ABDOMEN & PELVIS

15- Hepatobiliary System/Foregut

1. GI Embryologya. Mesentery : formed when liver penetrates mesenchyme of septum transversum

i. Dorsal mesentery : connecting liver to terminal part of esophagus down to initial part of duodenum (lesser omentum)

ii. Ventral mesentery : connecting liver to ventral body wall (falciform ligament)b. Rotation of the Stomach (90 degrees clockwise)

i. Original left side becomes the VENTRAL SURFACEii. Original right side becomes the DORSAL SURFACE

1. Greater curvature comes to lie caudally and to lefta. Lesser sac (omental bursa): space behind the stomach

i. Ulcerated Gastric Ulcer : gastric juices & stomach contents leak into lesser sac

iii. Lesser curvature located cranially and to rightiv. Left vagal trunk will be pulled anteriorlyv. Right vagus pushed posteriorly (“LARP” left anterior, right posterior)

c. Pancreas develops from two buds: i. Ventral bud (from duodenum) forms - uncinate process, part of

pancreas head, main pancreatic duct1. Annular Pancreas : ventral pancreas of two lobes migrate around

duodenum in opposite directions to fuse with dorsal buda. Infants : feeding intolerance, bilious vomiting, abd. distensionb. Adults : abdominal pain, nausea, vomiting, upper GI

bleed (stomach ulceration), acute/chronic pancreatitisii. Dorsal bud (from liver bud origin) forms - rest of pancreas, distal main pancreatic duct

d. Midgut elongation forms intestinal loop connected at its apex to vitelline ducti. Cephalic limb : rest of duodenum, jejunum, part of ileum

ii. Caudal limb : rest of ileum, cecum & appendix, ascending colon, proximal 2/3 of transverse colon

iii. Physiological umbilical herniation : loop elongates rapidly; because of enlargement of liver, abdominal cavity temporarily cannot accommodate the loop and it herniates into extraembryonic cavity

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2. Nothing is in the peritoneal cavity a. Parietal peritoneum : sensitive to somatic painb. Visceral peritoneum : insensitive to somatic painc. Intra-peritoneal organs :

i. Mesentary : double layer peritoneum between body wall & organ; convey all neurovascular structures to abdominal & pelvic organs

ii. Ligament : double layer of peritoneum between organsiii. Omentum : double layer peritoneum between stomach & another organ

d. Retroperitoneal organs : fixed in positioni. Anterior covered by visceral peritoneum (serosa) continuous w/ parietal peritoneum

ii. Posterior surface covered by connective tissue (adventitia)iii. Covered by nearly transparent parietal peritoneum

3. Peritoneal reflections: a. Lesser omentum (hepatogastric ligament): from liver

to stomach lesser curvature & first part duodenumi. Hepatogastric lig. : (superiorly) from liver to

lesser curvature of stomachii. Hepatoduodenal lig. : (inferiorly) free lesser

omentum margin from liver to first part duodenum1. Contains Portal Triad and forms roof of

epiploic foramen of Winslow (connecting the greater & lesser sacs)

b. Greater omentum (gastrocolic ligament): i. Gastrocolic lig. : stomach greater curvature to transverse colon

1. Nerves & vessels serving the stomach course between the two layers of the lesser omentum & the gastric-colic ligament

ii. Gastrosplenic lig. : stomach greater curvature to spleeniii. Gastrophrenic lig. : stomach fundus to diaphragm

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4. Foregut : distal 1/3 esophagus to duodenum at bile duct entrance; pain in foregut is referred to epigastric region

a. ESOPHAGUS : starts at C6i. Right crus of the diaphragm wraps around where esophagus enters

stomach, forming the esophageal hiatus1. Hiatal hernia : hernia of stomach through esophageal hiatus

a. Sliding hernia : common in patients with GERD (Right crus is weakened allowing herniation, reflux)

b. Paraesophageal hernia : (uncommon) normal Z-line & cardia; herniation of fundus - portion may become strangulated

ii. Lower esophageal sphincter : both inner circular & outer longitudinal layersiii. Cardiac orifice : esop opening into stomach (T10); no muscle sphincteriv. Zigzag (Z) line (esophageal-gastric junction): T11 tip xiphoid process;

transition of stratified squamous to simple columnar epitheliumv. Gastro-esophageal reflux disease (GERD): acid reflux to esophagus

1. Esophagitis (acute)2. Esophageal strictures: (chronic) scar tissue reduces lumen & peristaltic functioning

3. Barrett’s esophagus: metaplasia; adenocarcinoma precursor

b. STOMACH : i. Greater & Lesser curvatures:

ii. Fundus : superior to line connecting cardiac notch to greater curvatureiii. Body : inferior to this line, & superior to line connecting incisura angularis to greater curvature

1. Superior region – produces acid & pepsin2. Inferior region – produces alkali & gastrin

a. Gastrectomy : surgical removal of gastrin producing stomach part {gastric ulcers}; stomach reconnected to duodenum

iv. Pylorus : muscular area right of L1 made of pyloric sphincter & canal1. Antrum : small area between the body and the pylorus2. Congenital Pyloric Stenosis : non-bilious projectile vomiting,

abdominal pain, dehydration, failure to gain weightv. Ligament of Treitz : fibro-muscular band attaches duodenum to diaphragm;

duodenal-jejunal junction landmark, palpable through peritoneumvi. Parasympathetic inn. via Left vagus: (anterior) & Right vagus : (posterior)

vii. Sympathetic inn. via Celiac plexus: & Greater splanchnic nerves:

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c. SPLEEN : triangular organ left & posterior of the stomachi. Lienal-renal ligament : attaches spleen to posterior abdominal wall

ii. Rests on (but is not connected to) Phrenico-colic ligament: connects left colic flexure & diaphragm; where the spleen’s inferior border rests

1. Effective barrier (along w/ mesentery root) to infection spreadiii. Medial surface: smooth fossae where rests against each organ (kidney, stomach, colon)

iv. Splenic a. : {celiac trunk} reaches spleen by way of lienorenal ligament

d. LIVER : largest internal organi. Bare area : superior surface touching diaphragm, not covered by

peritoneum1. Bordered by coronary ligament (reflected peritoneum): extreme ends

are the right & left triangular ligaments: angular in shapeii. Ligamentum venosum : obliterated ductus venosus iii. Falciform ligament : (ventral mesentery) anterior abdominal wall to liver

1. Ligamentum teres (round ligament of the liver): obliterated left umbilical vein in free margin of falciform ligament

iv. Liver is divided into left & right halves via: 1. Anterior – Falciform ligament

a. Right & Left Lobe 2. Posterior – Fossa made by IVC & gallbladder

a. Quadrate lobe : between (& anterior) gall bladder fossa & ligamentum teres

b. Caudate lobe : between (& anterior) IVC & ligamentum venosum

v. Living donor liver transplants : 70% removed w/o complication; regrowth compensates but not true regeneration

vi. Portal Triad : consists of:1. Portal vein : union of SMV & splenic vein; receives material from

gut, spleen, pancreas; lipids collected by lymphatics & reach liver via hepatic arteries

a. Divides into right & left hepatic portal veins at the porta hepatis (transverse fissure of the liver) IVC

b. No venous valves - if veins become damaged, liver cannot process & clear incoming blood fast increased portal pressure esophageal varices

c. Cirrhosis : liver parenchyma atrophy & CT hypertrophyi. Sx: epigastric pain, hematemesis, jaundice, tachycar. low

BP; ascites, splenomegaly, caput medusa, hemorrhoidsii. Tx: shunt to IVC {temporarily relieve por. hypertension}

2. Common hepatic duct : a. Jaundice : bile pigment accumulation in blood streamb. Liver frequent site for secondary metastasis (great vascularity)

3. Proper hepatic artery :vii. Portocaval anastomoses : with reduced portal blood flow (portal hypertension)

blood can return to systemic circulation via:1. Esophageal, Rectal, Paraumbilical, Retroperitoneal veins

a. Esophageal varices : stretched v. may rupture hemorrhage

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b. Caput Medusae : dilated periumbilical v.

e. GALL BLADDER : pear-shaped organ in liver fossa which stores bile; develops as an outpouching of hepatic diverticulum

i. Fundus : at junction of 9th rib & linea semilunarisii. Body ; Neck:

iii. Cystic duct : series of pouches separated by cystic folds (act like valves {Spiral valve of Heister} to prevent spontaneous bile release); Hartman’s pouch: possible site for gall bladder stones to lodge

1. Joins hepatic duct at porta hepatis to form common bile duct, which then joins the pancreatic duct before entering duodenum

2. Gall stones : stretching, twisting & bile release stone trappinga. Lodged in cystic duct Cholecystitis: stagnant bile

trapped in gallbladder leading to inflammationb. Lodged in common bile duct Jaundice (yellow color)c. Lodged in hepatopancreatic ampulla (where bile mixes

with pancreatic enzymes) Pancreatitisiv. Cystic artery (arises from right hepatic artery)

f. PANCREAS : posterior to stomach & abdominal cavity peritoneumi. Head : lies in the C-shaped portion of the duodenum

1. Uncinate process : extends posterior to superior mesenteric vesselsii. Neck : more constricted than the head

iii. Body : runs from the right to left connecting the neck to the tailiv. Tail : lies at the spleen hilusv. Main pancreatic duct (Duct of Wirsung): enters duodenum with the

common bile duct, forming Ampulla of Vater at duodenal papilla through Sphincter of Oddi: controls bile & pancreatic secretions in duodenum

1. Spasms of Sphincter of Oddi may result in regurgitation of bile into pancreas acute & severe inflammation, pancreatitis

vi. Accessory pancreatic duct (Duct of Santorini): vii. Usually not subject to trauma damage - exception of gastric surgery

g. DUODENUM : 1st & ½ of 2nd Parts is foregut: i. First : (5cm) mucous membrane is smooth (vs. rest of duodenum where

it is thrown into folds [plicae circulares])ii. Hepatopancreatic ampulla (ampulla of Vater): dilatation from junction of

common bile & pancreatic ducts proximal to opening in duodenal; located at1. Major duodenal papilla : location of initial formation outgrowth

a. Tissue proximal to this (foregut) supplied by celiac trunkb. Tissue distal to this (midgut) supplied by SMA

iii. Second : (8cm) descendingiv. Third : (8cm) inferior, horizontal

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v. Fourth : (5cm) ascending

5. Abdominal aorta : bifurcates at L4 (umbilicus {L3} aorta palpation)a. Left and right common iliac a.s:

i. Internal iliac a. (2): external genitalia, anal canal, perineumii. External iliac a. (2): ext genitalia, abd. wall ( femoral a.)

b. Somatic/Parietal Branchesi. Lumbar a. : 1st - 4th lumbar a.; posterior intercostal a.

ii. Median sacral a. : gives rise to 5th lumbar arteriesiii. Inferior phrenic a.s : diaphragm; gives off 2-3…

1. Superior suprarenal arteries : adrenal glandsc. Paired Visceral Branches

i. Renal a.s : Inferior adrenal branch: adrenal glandsii. Gonadal a.s :

iii. Middle suprarenal a .s : adrenal glandsd. Unpaired Visceral Branches

i. Celiac trunk : from aorta ventral surface just below diaphragm at T12; supplies most of the foregut via:

1. Left gastric : lower esophagus, less. cur. stomach a. Esophageal branch :

2. Splenic : (left) spleen, pancreas, stomacha. Left gastroepiploic : stomach greater curvature; greater omentum

b. Short (left) gastric : stomach fundus3. Common hepatic : (right)

a. Right gastric : stomach lesser curvatureb. Gastro-duodenal : duodenum

i. Right gastroepiploic : through greater omentum; anastomose w/ left gastroepiploic along greater curvature

ii. Superior pancreatico-duodenal : pancreas, duodenum

Common hepatic becomes….4. Hepatic Artery Proper : extends up towards liver, enclosed in

lesser omemtum (hepato-duodenal ligament / Portal triad)a. Right hepatic : right lobe, ½ caudate lobe, gall bladder

i. Cystic artery : gall bladder; passes through Triangle Of Calot (cystic-hepatic triangle: bounded by cystic duct, hepatic duct, liver lower edge)

b. Left hepatic : left lobe, quadrate, ½ caudate (caudate ~ fish tail)

ii. Superior mesenteric a. : ventral aorta 1cm below celiac L1 level; supplies midgut1. Inferior pancreaticoduodenal a .: pancreas head, uncinate process2. Right colic a. : ascending colon3. Middle colic a. : proximal 2/3 transverse colon (part of marginal a.)

a. Vasa recta : do not anastomose; long in jejunum, short in ileum4. Jejunal a. : small intestine jejunum5. Ileocolic a. : terminal ileum, cecum, appendix, ascending colon6. SMA Syndrome : compression of the 3rd part duodenum by SMA;

may also compress left renal vein dilation of 1st & 2nd parts, nausea & billous vomiting (curdled milk & bile); relieved by leaning forward

iii. Inferior mesenteric a. : aorta 3cm above L3 bifurcation; supplies hindgut

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1. Left colic a .: transverse colon (part of marginal a.), descending & sigmoid colon

2. Sigmoid a .: sigmoid colon; lower descending colon6. Inferior Vena Cava :

a. Hepatic veins : receive blood from the liver and terminate in the IVCb. Union of Superior Mesenteric Vein & Splenic Vein {at L2 level}

i. Portal Vein: right & left branches enter the porta hepatis1. Splenic v. :

a. Left gastroepliploc v.:b. Inferior mesenteric v.:c. Pancreatic v.:d. Short gastric v.:

2. Superior mesenteric v. : ileum, jejunum, cecum, sigmoid, ascending, transverse3. Left & Right gastric v.:4. Paraumbilical v.: 5. Cystic v.:

7. Nerves : the major innervation of the visceria is autonomic a. Sympathetic Innervation :

i. Preganglionic fibers : greater splanchnic n. (T5-T9)ii. Post-ganglionic fibers : accompany blood vessels

iii. Sympathetic trunk (Thoracocolumbar): 1. Esophageal Nervous Plexus : esophagus, stomach fundus, left colic flexure

a. Anterior & Posterior Vagal Trunks: Synapse in the Celiac & Superior Mesenteric Plexuses: 2. Thoracic Splanchnic Nerves (T5-12): Foregut & Midgut

a. Greater splanchnic n. (T5-T9): i. Branches to: descending thoracic aorta,

suprarenal glandsb. Lesser splanchnic n. (T9-10):

i. Renal branchesc. Least splanchnic n. (T12):

3. Lumbar Splanchnic nerves (L1-3): Hindgut

b. Parasympathetic innervation via Vagus n. (CNX): Stimulates bile production & glycogen synthesis, but hormones control most functions via enteric NS - 50x more preganglionic neurons

i. Pelvic splanchnic nerves (ventral primary rami S2-4): hindgut1. Passes to the Rectal plexus

c. Subcostal n. (ventral primary rami T12): abdominal musclesd. Lumbar Plexus (ventral primary rami T12-L4):

i. Iliohypogastric n (L1-T12): suprapubic skinii. Ilioinguinal (L1): skin of: penis, scrotum, mons pubis, labium major

iii. Genitofemoral n. (L1-2): cremaster muscle, same skin as ilioinguinaliv. Lateral femoral cutaneous n. (dorsal branches of ventral rami L2-3): v. Femoral n. (L2-4):

vi. Obturator n. (L2-4):vii. Lumbosacral trunk (L4-5):

8. Lymphatics :a. Foregut drains into nodes named after their structure drain superior mesenteric n. to celiac

i. Pre-aortic nodes = inferior mesenteric, superior mesenteric, & celiac nodes

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ii. Celiac nodes drain to the cisterna chyli, and then into the thoracic duct

16- Midgut/Hindgut

1. Midgut : from opening of bile duct into duodenum until 2/3 through transverse colon

a. SMALL INTESTINE : i. Jejunum : [ULQ] upper 2/5 excluding duodenum; greater diameter &

thicker wall (large plicae circulares); longer vasa recta (versus ileum)ii. Ileum : [LRQ] lower 3/5 of small intestine

1. Meckle’s diverticulum : persistence of the yolk stalk in adult in ileum ~3 ft from terminal end; usually asymptomatic but may become inflamed & give appendicitis-like symptoms

a. May contain pancreatic/gastric tissue, and develop ulcer2. Omphalocele : small intestine fails to be completely drawn into

abdomen after rotation hernia filled w/ small bowel covered with amniotic membrane protruding out of abdomen

3. Volvulus : incomplete gut rotation midgut loosely suspended by long mesentery - may become twisted or tangled

iii. Mesenteric Ischemia : arteries supplying small intestines (from SMA) blocked1. Sx: Sudden mid-abdominal pain; normal bowel sounds, minimal tenderness2. Hx: myocardial ischemia, peripheral vascular disease

b. LARGE INTESTINE : greater diameter than S.I.; performs some absorption (water)i. Iliocecal junction : functionless ileocecal valve: forms frenulum ridge)

1. Colon Intussusception : invagination of ileum into cecum through ileo-cecal valve intestinal obstruction; usu. 1y/os

a. Causes: benign/malignant growths, adhesions (scars), motility disorders, long-term diarrhea

ii. Cecum : sac lying below the ilio-cecal junction1. Carcinoma of the Cecum : 2nd leading cause of cancer death;

mass protruding into lumen usually arising from mucosa; neoplastic, hyperplastic, or inflammatory in etiology

iii. Vermiform appendix : at McBurney’s point; base attached to cecum, appendix itself attached to ileum’s mesentery (via mesoappendix)

1. Appendicitis : causes deep pain in right iliac fossa (RLQ)a. Pain severe & localized once peritoneum involvedb. Afferent nerves enter T10 referred pain around umbilicus

iv. Ascending colon : when reaches right (hepatic) colic flexure becomes 1. Transverse colon : to left (splenic) colic flexure (more superior)

v. Diverticulosis : (sigmoid) outpouchings (herniation) of colonic mucosa & submucosa through muscle wall layer weaknesses; due to low-fiber diet, constipation which increases intra-luminal pressure

vi. Crohn’s Disease : chronic relapsing inflammatory condition 1. Sx: diarrhea, abdominal pain, weight loss, constitutional symptoms

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c. Taenia coli : colon external longitudinal muscle division into 3 bands; ‘purse-string’ effect & colonic out-pouching (Haustra coli)

d. Epiploic appendages : small fat pouches along colon except cecum, appendix, & rectum2. Hindgut : posterior (caudal) part of the alimentary canal

a. Splenic (left) flexure of colon: transverse descending colonb. Descending colon : to the pelvic brim where it becomes the..

i. Sigmoid (pelvic) colon : which continues to the rectum c. Upper 1/3 rectum : terminates at levator ani attachment (pectinate line/anorectal junction)

i. Inside of the rectum is thrown into folds (rectal valves)ii. Internal hemorrhoids : above pectinate line & outside rectal columns

iii. External hemorrhoids : below pectinate line; seen when enlargedd. Inferior mesenteric artery : from aorta ~4cm above bifurcation

i. Left colic : 1. Ascending (superior) branch : distal 1/3 transverse, superior descending

2. Descending (inferior) branch : lower descending colonii. Sigmoid branches :

iii. Superior rectal (hemorrhoidal a.) : branches obliquely encircle rectum1. Middle rectal (internal iliac b.) & inferior rectal (internal pudendal b.)

arteries anastomosis in rectum wall - can supply entire rectum if IMA (& superior rectal a.) clamped

e. Marginal Artery of Drummond : anastomosing ends of superior & inferior mesenteric a.

f. Rectal plexus of veins : i. Upper – tributaries form superior rectal vein inferior mesenteric

veinii. Middle – passes to internal iliac vein (with tributaries from bladder, prostate, seminal vesicle)

iii. Inferior part – drains into internal pudendal veing. Lymphatics

i. Rectum: inferior mesenteric group of pre-aortic lymph nodesii. Anal canal: internal iliac nodes (along middle rectal a.) lateral aortic nodes

iii. Anus: (below white line of Hilton) join those of perineum & scrotum superficial inguinal nodes

16b- Autonomic Innervation of GI track

1. SYMPATHETIC : regulation of blood flowa. Greater Splanchnic nerves (T5-T9): from

intermediolateral cell columns, travel along spinal ventral roots, synapse celiac ganglia

i. Then along blood vessels to foregut b. Lesser Splanchnic nerves (T10-T11):

synapses in superior mesenteric gangliai. Supplies midgut

c. Least Splanchnic nerves (T12): synapses in aortico-renal ganglia

i. Regulate blood flow to kidneys

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d. Lumbar Splanchnic nerves (L1-L2): synapse in inferior mesenteric gangliai. Regulate blood flow to hindgut

2. PARASYMPATHETIC : peristalsisa. Vagus nerve : thorax, abdomen, GI tract up to transverse colon boundaryb. Craniosacral : Pelvic splanchnic nerves (S2, 3, 4): hindgutc. Hirschsprung’s Disease : congenital absence enteric PS ganglia in distal colon

i. Absence of peristalsis, dilation of proximal colon, constipation, failure to pass meconium, abdomen distension

d. Motility of the Large Intestinei. Haustra sequentially contract as they are stimulated by distension

ii. Presence of food in stomach gastrocolic reflex & peristalsisiii. Defecation

1. Fecal distension of rectal walls rectal contractiona. Relaxes internal anal sphincter (Pelvic splanchnic n)

2. Voluntary relaxation external anal sphincter (Pudendal n)

3. Autonomic nervous system is a visceral motor systema. Somatic sensation: conscious, sharp, well-localized

i. Touch, pain, temperature, pressure, proprioceptionb. Visceral sensation: often unconscious; if conscious – dull & poorly localized

i. Distension, blood gas, blood pressure, cramping, irritantsc. Visceral afferent sensory nerves (GVA): sensory CNS feedback about autonomic requirement

i. Run with sympathetic & parasympathetic nerves ii. Cell bodies in dorsal root ganglion; Nerve ending in viscera

iii. Referred pain : pain originating in visceral structure perceived as from area of skin innervated by same segmental level as the visceral afferent

1. From convergence of somatic & visceral afferents on same segmental level - “Cross-talk” in dorsal horn

Organ Spinal Level Site of Referred PainStomach T5–T9 Epigastric or left hypochondriumDuodenum T5–T8 Epigastric or right hypochondriumJejunum T6–T10 PeriumbilicalIleum T7–T10 PeriumbilicalCaecum T10–T11 Periumbilical or right lower quadrantAppendix T10–T11 Periumbilical, then to right iliac fossaAscending colon T10–T12 Periumbilical or right lumbarSigmoid colon L1–L2 Left lower quadrantSpleen T6–T8 Left hypochondriumLiver & gallbladder

T6–T9 Epigastric, later to right hypochondrium

Pancreas T7–T9 Inferior epigastrium

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Kidney T10–L1 Small of back, flankUreter T11–L1 Loin to groin

17- Posterior Abdominal Wall/Urinary System

1. Lumbar vertebrae location markersa. Transpyloric (L1) b. Subcostal (L2) along lowest part of rib cage (rib 10)c. Transiliac (L4) upper edge of iliac crest

2. Anal canal : lining continuous with skin at white line of Hilton (intersphincteric line: small indentation between internal a.sphincter & subcutaneous external a.sphincter)

a. White line of Hilton : anus transition point nonkeratinized to keratinized st. sq. epi.b. Internal anal sphincter : involuntary circular fibers

i. Innervated by PS ns. from S2, 3, 4; not innervated by pudendal n. (somatic n.)a. External anal sphincter : voluntary; always in tonic contraction

3. DIAPHRAGM : a. Openings:

i. Caval orifice (T8): inferior vena cavaii. Esophageal sphincter (T10): formed by arching fibers of right crus

iii. Aortic orifice (T12): aorta passes behind diaphragm between R & L crusb. Left crura : from vertebrae L1-L2c. Right crura : from vertebrae L1-L3d. Lumbocostal arches (arcuate ligaments): diaphragm crosses quad.lumborum & psoas

i. Medial arcuate ligament : (over psoas major m.)ii. Lateral arcuate ligament : (over quadratus lumborum m.) over subcostal n. (T12)

iii. Median arcuate ligament : (between R & L crus) over aorta & cysterna chyli

e. Congenital Diaphragmatic Hernia : abdominal organs push into lung formationf. Eventration of Diaphragm : elevation of diaphragm due to congenital

malformation or phrenic nerve interruption from birth or operative traumaa. Phrenic nerve : motor fibers & also sensory fibers to central diaphragmb. Intercostal nerves : sensory fibers to peripheral partc. Blood supply: musculophrenic, pericardiophrenic, superior & inferior phrenic

4. POSTERIOR ABDOMINAL WALL : a. Psoas major : passes with iliacus under inguinal ligament (iliopsoas: covered

by dense fascia – muscles & lumbar plexus behind fascia, iliac vessels in front)i. Flexes hip joint; Innervated by L1, 2, 3 inside abdomen

ii. Psoas Sign : pain on passive extension of right thigh

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1. Inflamed appendix is in a retroperitoneal location in contact with the psoas muscle which is stretched by this maneuver

b. Psoas minor : small muscle belly whose long tendon lays over psoas majorc. Quadratus lumborum : lateral to psoas, running between iliac crest & R12

i. Side trunk flexor; Innervated segmentally by adjacent lumbar nervesd. Transverse abdominus : arises from the thoracolumbar fasciae. ADRENAL GLANDS : embedded in perinephric fat

i. Cortex : production of steroidsii. Medulla : source of epinephrine – secreted by chromaffin cells

1. Derived from neural crest cells: where preganglionic abdomino-pelvic splanchnic nerves synapse

2. Pheochromocytoma : tumor of the chromaffin cells; large suprarenal mass, sympathetic system overdrive

iii. Right adrenal gland : triangular shape1. Posterior – diaphragm2. Medially anterior – IVC; Laterally anterior - liver

3. Between the adrenal glands are the celiac trunk & celiac plexus4. Left adrenal gland : crescent shape; descend to the hilus of the L kidney

a. Posterior – diaphragm left crusb. Anterior – stomach; Inferior – pancreas

5. Only one large venous branch leaving each adrenal gland at the hilusa. Left adrenal v. left renal vein; Right adrenal v. IVC

f. KIDNEYS : lie on psoas major, quadratus lumborum and transversus abdominis; develop in pelvis, ascend to T12 level; lie in a paravertebral gutter

i. Per i renal space : inside fascia, around kidneys; Pararenal space: around fasciaii. Signs of Retroperitoneal bleeding :

1. Cullen’s Sign : tracking of liberated pancreatic enzymes to ant. abd wall from gastrohepatic ligament across falciform ligament

2. Grey-Turner’s Sign : tracking of blood-stained pancreatic exudate from anterior pararenal space through tissue planes (including posterior renal fascia) to the abdominal wall

iii. Hilum : where renal arteries enter the kidneysiv. Major, minor calices : minor form major calices, form pelvis ureter partv. Ureters : pass anterior to psoas m. & common iliac a. bifurcation into pelvis

vi. Pelvic kidney : fails to ascend to the abdomen from the pelvicvii. Ectopic kidney : has migrated to an abnormal position

viii. Horseshoe kidney : primordial kidneys fuse, usually at inferior polesix. Kidney stone : passage may give rise to referred pain from the testis

(testicular plexus at T10) since afferents from the kidney enter at T12x. Surgical access to kidney through lumbar triangle (fewer muscle layers)

5. Lymphatics a. Pre-aortic nodes : in front of the aorta

i. Celiac nodes : ii. Superior mesenteric nodes :

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iii. Inferior mesenteric nodes : iv. all unite to form the intestinal trunk enters the cisterna chyli (a

dilated sac marking the inferior end of the thoracic duct)b. Para-aortic (lateral aortic) nodes: in front of vertebral bodies, near aorta

i. Drains: posterior abd. wall, kidneys, adrenal glands, pelvic organs, lower limbc. Thoracic duct : starts at L2 & extends to root of the neck

i. Origin in abdomen from confluence of R & L lumbar & intestinal trunks

6. Abdominal aorta : enters abdomen under median arcuate ligament at T12, ends at L4 left of midline

a. Lateral branches (suprarenal glands, kidneys, gonads)i. Renal arteries : ¼ of cardiac output; arise just below SMA; enter

kidneys at the hilus posterior to renal veins1. Right renal a .: passes posterior to inferior vena cava; longer2. Left renal a .:3. Inferior adrenal a. :

ii. Middle suprarenal branch : to suprarenal glandsiii. Gonadal (ovarian or testicular) a.: arise from aorta just below renal a.

1. Descend anterior to surface of psoas to reach ovary, or2. Pass into the inguinal canal to go to the scrotum

b. Branches to the body walli. Inferior phrenic a .: ramify on inferior diaphragm surface

1. Superior adrenal branches (6-8): suprarenal glandsii. Lumbar a . (4):

1. Anterior branch : between transversus & internal oblique m.2. Posterior branch : goes through the back giving a spinal branch

iii. Median sacral a .: midline, anterior to sacrum; main continuation of aortac. Repair of Abdominal Aortic Aneurysms : put in stent (clamp aorta above &

below), insert catheter into femoral & ext. iliac, then aorta; stent distributes blood from aorta

7. Inferior Vena Cava : begins in front of L5, ascends to diaphragm, pierces central tendon at T8a. Renal veins :

i. Above – veins lie anterior to corresponding arteriesii. Below – arteries lie anterior to the veins

b. Tributaries may be deduced from branches of the aortai. Ventral branches: drain to the portal system

1. Hepatic veins : drain to IVCii. Lateral tributaries: correspond to the named arteries except on the left

where the suprarenal & gonadal veins open in the left renal veiniii. Body wall tributaries:

1. Inferior phrenic & lumbar veins: drains into IVC2. Median sacral : drains into left common iliac vein

8. Lumbosacral plexus : roots L1-L5 are the ventral primary rami of spinal nervesa. L1: iliohypogastric & ilioinguinal nerves: both course along quadratus

lumborum to anterior abdominal wall, with iliohypogastric lateral

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b. L1 + L2: genitofemoral nerve: courses through and more medially along the psoas muscle to turn laterally to the anterior abdominal wall

i. Motor innervation to cremaster m.c. L2 + L3: lateral femoral cutaneousd. L2 + L3 + L4: femoral & obturator nervese. L4 + L5: lumbosacral trunk, which joins sacral nerves to form sacral plexus

18- Cross-Sectional Anatomy

1. X-rays – beam attenuation affected by: tissue density & thickness, x-ray energy (kV)a. Structural elements that attenuate the beam to a greater extend than air (black)

or are less attenuating than bone (white) show in various shades of grayb. Four basic densities:

i. Air – least absorbing {black}ii. Soft tissue {gray}

iii. Fativ. Bone - most absorptive {white}

2. Approach to plain film interpretationa. What is the normal & variant anatomy?

i. Situs inversus : congenital invariant where heart and aortic arch are rotated to the right side (normally left-sided structures)

b. Check for clues in the skin & soft tissuesc. Evaluate bones (Position/alignment, cortex, density, internal architecture, focal lesions)

3. Ultrasonography : a. Uses sound waves of frequencies 2 to 17 MHz b. Images from propagation & surface reflection of sound waves through body c. Time it takes sound waves to return provides information on tissue position d. No ionizing radiation - Uses sound waves to visualize structurese. Very operator dependentf. Can not penetrate boneg. Mainstay of diagnosis for:

i. Ob-gyn; Pediatric / Young womenii. Screening for vascular, abdominal & renal pathology

iii. Thyroid/neck pathology; Palpable lesions: Breast & Musculoskeletalh. Colour Doppler : velocity & direction

4. CT (Computer Tomography)a. Cross-sectional with multiplanar reconstruction & 2D imaging to assess vascularityb. Tube rotates around body and stationary circle detects penetrating x-raysc. Limitations: $$$

i. Ionizing radiationii. Requires contrast: IV and oral - prep time (1-2 hours)

1. Nephrotoxic; fatality rate 1:50,000 (even with low osmolar contrast)iii. Patient must be supine (prone)

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5. MRI (Magnetic Resonance Imaging)a. Rapidly switching magnetic field gradients align H protons (water and fat)b. When the gradients are turned off, a faint radiofrequency signal is produced

i. Different tissues absorb & give off different amounts of RF energy (different resonances)

c. Image is reconstructed using Fourier transformsd. Multiplanar and vascular assessment possiblee. Offers greatest “contrast” in tissue imaging technology (knee, ankle diagnosis)f. Mainstay of diagnosis for:

i. Neurologic imagingii. Musculoskeletal imaging (after plain film)

iii. Magnetic Resonance Angiography 1. Angiography without iodinated contrast : no arterial puncture (no

risk of vascular damage); 3D view of arteries & adjacent organsiv. Expanding applications in chest, abdominal, breast, & pelvic imaging

g. Advantages: i. True multiplanar imaging

ii. Intravenous contrast not usually required; No ionizing radiation iii. Minimize problems with claustrophobia

h. Limitations: $$$$ {$1450 - $2000}i. Ferromagnetic objects cause artifacts that limit imaging

ii. Contraindicated for patients with1. Implantable devices: cochlear implants, pacemakers*2. Metal shavings in orbits3. Severe renal failure

iii. Requires more cooperation and longer time than CT {30 min - 2 hrs}

6. Fluoroscopy : a. Dynamic radiography

i. Permits real-time evaluation of the gastrointestinal tractii. Barium Swallow (esophagus)

iii. Upper GI Series (stomach); Small Bowel Follow-throughiv. Barium Enema (colon)

b. Barium appears white on images (high density attenuates the x-ray beam)c. Assess both intrinsic (mucosal) & some extrinsic (mass-effect) abnormalities

7. Nuclear Medicine – GI Bleeding Scan

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a. Radiopharmaceutical = Tc99m in-vitro labelled RBCsb. Sequential 5 minute images acquired over an hourc. Looking for progressive accumulation of tracer

8. Gallium Scan : used for lymphoma staging & responsea. Baseline imaging determines whether the tumor is gallium-avidb. Serial scans assess response to treatment - can distinguish scar from residual tumor

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19- Male/Female Pelvis & Perineum

1. PERINEUM : region inferior to pelvic diaphragm between the legsa. Boundaries:

i. Anterior - Pubic symphysis: fibrocartilage; Posterior – Coccyx:ii. Lateral – Ischial tuberosities: hamstrings origin; Obturator internus m.

iii. Anterolateral – Ischiopubic ramus:iv. Posterolateral - Sacrotuberous ligament:

b. Diamond-shaped area subdivisionsi. Urogenital triangle (anterior): anus, external

anal sphincter, levator ani, obturator internus muscleii. Anal triangle (posterior): area bounded by

ischial tuberosities laterally and the coccyx posteriorly; perineal body, anal opening, midline anococcygeal raphe

2. Pelvic brim : divides greater (false) from lesser (true) pelvis from sacrum, ilium arcuate line, pectineal line (pectin of pubis) & pubic crest

3. Pelvic Floor : made up of a. Pelvic diaphragm : dividing line between pelvis &

perineum; forms floor of abdominal & pelvic cavities, consists of paired levatores ani & coccygeus muscles

b. Urogenital diaphragm : 4. Sacrospinous ligament : posteriorly holds hip to sacrum

a. Prevents upward motion; crossing of these two ligaments (Sacrotuberous/sacrospinous) forms sciatic foramen on either side of ischial spine

5. Obturator foramen : passage for obturator nerve6. Lesser sciatic notch : from pelvis into perineum (pudendal nerve)7. Greater sciatic notch : from pelvis to gluteal region (sciatic nerve, piriformis)8. Ala : attachment of piriformis muscles

9. Blood vessels: a. Ovarian a .: branches directly form the aorta just inferior to renal a. b. Common iliac artery :

i. Internal iliac a .: pelvis & perineum1. Obturator a : pelvic muscles, hip joint2. Superior & Inferior gluteal a.s.:3. Obturator a .: medial thigh4. Uterine & Umbilical a.: (near broad ligament) cervix, vagina, uterine tube, round ligament

5. Middle Rectal (hemorrhoidal a.): lower rectum 6. Internal pudendal a .: perineum

a. Inferior Rectal :

c. Veins form an anastomotic basket lining pelvic cavity – functionally one networki. Unite to form internal iliac veins (2), which unite with corresponding

external iliac veins to form common iliac veins to the IVC

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10. Nerves: a. Pudendal n .: (S2-4) provides the only TTPP & voluntary efferent fibers to anal canal

i. Passes through greater & then lesser sciatic foramen to enter ischiorectal fossa where it enters the pudendal (Alcock's) canal

ii. Posterior scrotal n. : innervate posterior scrotum walliii. Perineal b. : Motor to bulbospongiosus, perineal, sphincter urethra

1. Somatic sensory innervation to the labia via Ilioinguinal, genitofemoral, & Posterior Labial nerves

iv. Deep perineal b. : to muscles of the UG diaphragm & superficial pouchv. Inferior rectal b. : cross medially to sphincter ani muscles

b. Sacral plexus (lumbosacral S2-4): pelvis, lower limbc. Pelvic splanchnic n . (efferent PS fibers from S2-4): motor to wall of bladder

& rectum, inhibitory to bladder sphincter, vasodilator fibers to erectile tissue

11. Muscles: a. Levator ani : supportive muscles for midline pelvic organs

i. Iliococcygeus : {posterior} arises from the fascia of internal obturator1. Ischiorectal (ischioanal) fossa : fat-filled space between

obturator internus & levator ani; accommodates rectal filling & emptying related to defecation

a. Lateral wall – obturator internus; Medial wall – external anal sphincterb. Superior – levator ani; Inferior – superficial fascia & skinc. Floor – UG diaphragm

ii. Pubococcygenus : {anterior} attaches to inner surface of pubic bone & obturator fascia; passes back lateral to anal canal to reach the coccyx

1. Puborectalis : part of the pubococcygeus muscle that wraps around posterior rectum, forming a sling around anorectal junction that maintains flexure & holds rectum forward

b. (Ischio-) Coccygeus : fused with sacrospinous lig; attaches to spine of ischiumc. Obturator internus : forms the pelvis lateral wall

12. Urinary bladder : sac on the pelvic floor {true pelvis} - shape affected by age, sex, urine vol.

i. Males: superior to prostate; separated from rectum by restovesical pouchii. Females: inferior to uterus, anterior to vagina; separated rectum by vesicouterine pouch

b. Detrusor muscle : smooth m. fibers in spiral, longitudinal, & circular bundlesi. Stretch receptors - Afferent (sensory) impulses enter spinal cord

(S2-S4) via Pelvic Splanchnic n. PNS contracts expel urine via1. Internal sphincter (autonomic) & external sphincter (voluntary)

ii. Parasympathetic fibers: 1. Preganglionic : pelvic splanchnic n. synapse in inferior hypogastric plexus2. Posganglionic : to bladder m. induce reflex contraction of

detrusor muscle & relaxation of internal sphincter3. Pudendal n. somatic fibers : voluntary relaxation ext sphincter

iii. Sympathetic fibers: relax bladder, contract internal sphincter {inhibit emptying}; also prevent reflux retrograde ejaculation into bladder

c. Trigone : smooth triangular region at bladder base where ureters enter; very sensitive to expansion – stretching sends emptying signals to brain

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13. MALE PELVIS : a. Seminal vesicles : glands postero-inferior to bladder whose secretions are

responsible for primary alkalization of semen; duct opens into vas deferensb. Vas (ductus) deferens : transports sperm from epididymis to ejaculatory duct

i. Vasectomy : transection/ligation; reliable form of birth control for menc. Ureter : passes inferior & medial to Vas deferens to enter posteolateral bladderd. Prostate : cone-shaped chestnut-sized gland of CT & smooth muscle that rests

on superior levator ani with urethra passing through urogenital hiatuse. Ejaculatory Duct : formed at junction of ductus deferens & seminal vesicle

i. Prostatic urethra : passes directly through prostate gland1. External Urethral Sphincter constricts during ejaculation

ii. Membranous urethra : passes through the UG diaphragmiii. Penile (spongy) urethra : passes through the corpus spongiosum

1. Compressed by the bulbospongiosus muscle during ejaculation2. Rupture : urine/blood pass into superficial perineal pouch,

scrotum, penis shaft, and lower abdominal wallf. Bulbo-urethral (Cowper’s) glands: lie within substance of UG diaphragmg. Sexual episode:

i. Erection : blood filling cavernous bodies (parasympathetic “Point”)1. Pelvic Splanchnic n .: dilates erectile tissue arteries causing

engorgement, compressing veins (impeding venous return) ii. Emission : contraction of smooth muscle deposits semen in urethra

iii. Ejaculation : contraction of bulbospongiosus m. (sympathetic “Shoot”)h. PENIS :

i. Bulb of penis : (posterior) located in superficial pouch (inferior to perineal membrane/ UG dia.); covered by the two bulbospongiosus muscles

ii. Corpus cavernosum : (dorsal & anterior) formed by the two crura (attached to inferior pubic rami) coming together in the shaft portion of the penis

iii. Corpus spongiosum : (ventral) enlarges distally to form glans penis1. Gland penis : distal end of corpus cavernosum2. Urethra : passes through the bulb & corpus spongiosum

iv. Penis: 1. Posterior femoral cutaneous n. (S1-3): scrotum2. Pudendal n. (S2-4):

a. Dorsal n. of Penis : corpus spongiosum, penile skinb. Perineal n.: bulbospongiosus, sphincter urethra, scrotum

3. External & Internal pudendal a.: genitalia, anal canal, perineum, scrotum

a. Deep a. : to the crus; Dorsal a.: gland penis4. Superficial dorsal vein : along superficial surface of corpus

cavernosum external pudendal vein great saphenous vein5. Deep dorsal vein : ends in the prostatic plexus6. Superficial inguinal nodes: penis skin & glans, scrotum7. Internal Iliac nodes: erectile tissue8. Paraoartic lymph nodes: testes

v. Testicular vein : formed by pooling of the pampiniform venous plexus 1. Right test. v .: drains to IVC; Left v.: drains to left renal vein

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14. FEMALE PELVIS : a. Adnexa : uterine tubes, ovaries, & their associated mesenteriesb. Vagina : tubular organ from posterior fornix to opening in vestibule

i. Fornix : 1. Anterior & Lateral : digital examination allows palpation of

urethra & bladder (A); ovaries, uterine tubes, ureters (L)2. Posterior : site of Culdocentesis (aspiration of fluid from

rectouterine pouch by puncture of the vaginal wall)c. Rectouterine pouch of Douglas : most inferior extent of peritoneum; frequent

location for ectopic pregnancy or pooling of fluid (which becomes palpable)d. Uterosacral ligament : form the lateral walls of recto-uterine pouche. Vestibule : openings of urethra (A) & vagina (P); divides UG triangle into R & L

1. Bulbs of the vestibule : erectile tissueii. Labium majus : folds of tissue with subcutaneous fat located on either

side of the vestibule; receives termination of the round ligamentsiii. Labium minus : folds fat-free hairless skin enclosed by labia majoraiv. Clitoris : on anterior vestibule; contains erectile tissue pair of corpora cavernosa

f. Fallopian (uterine) tubes: enters uterus at each superolateral angleg. Cardinal ligament (transverse cervical lig. of Mackenrodt): normally is

what supports the uterine angle (anteversion); cut during hysterectomyh. Uterus : midline pear-shaped organ of a fundus, body, isthmus, & cervix

i. Cervical canal : narrow and terminates as the external osii. Caudal epidural : anesthetizes lower birth cancal (cervix, lower

uterus, external genitalia) not fundus & body of uterusiii. Pudendal nerve block : anesthetizes skin of external genitalia

i. Broad ligament : double layer of peritoneum holding the uterus to the lateral walls of the true pelvis; also encloses the uterine tube in its upper free border

i. Three subcomponents of the broad ligament: 1. Mesosalpinx : (over uterine tube) most superior portion2. Mesovarium : (over ovary) connects ovary to broad ligament

a. Ovarian ligament : {in broad ligament} ovary to uterus3. Mesometrium : (largest) (over uterus) mesentery of the uterus

a. Transmits uterine & ovarian arteriesb. Round ligament of uterus : {within broad lig.} maintains

uterine anteversion (ventrally) during pregnancyj. Ureter : lies above fornix and is crossed superiorly by uterine vessels; (“water {ureter} flows

under the bridge {uterine a.}”); pelvic surgery injury risk (hysterectomy)

k. Superficial perineal space (external genitalia, rectum, bartholin’s glands): Inguinal lymph nodes superior anterior thigh external iliac nodes

l. Deep perineal space (sphincter m., uterus, ovary, bulbourethral glands, pudendal n. & a.) Internal iliac nodes & lateral sacral nodes common iliac

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