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The Abdomen
Surface Anatomy, Vessels,
Muscles, and Peritoneum
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Abdominopelvic Cavity
Ventral body cavity
Thoracic
Abdominopelvic
Abdominopelvic
Abdominal Liver
Stomach
Kidneys
Pelvic cavity
Bladder
Some reproductive organs
Rectum
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AbdominopelvicCavity
Surrounded by theabdominal walls andpelvic girdle
The two cavities arecontinuous
Most organssurrounded by a
peritoneal cavity Visceral peritoneum
Serous peritoneum
Peritoneal cavity
pg242
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Abdominal Quadrants
9 regions
4 quadrants
Draw line through
navel Right upper
quadrant
Left upper quadrant
Left lower quadrant
Right lowerquadrant
pg
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Surface Anatomy
Anterior abdominal wallextends from costal marginto inferior boundaries: Iliac crest
Anterior superior iliac spine
Inguinal ligament Pubic crest
Superior boundary Diaphragm
Central landmark Umbilicus
Linea alba (white line) Tendinous line
Extends from xiphoid processto pubic symphysis
pg345
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Muscles
Function: Help contain abdominal organs
Move trunk
Forced breathing
Increase intra-abdominalpressure
Abdominal wall Anterior (4) Innervated by intercostal nerves
Continuous with layers ofintercostal muscles
Fibers of layers run in differentdirections for strength
Ends in aponeurosis which
contains rectus abdominismuscle
Posterior (3)
pg250
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Anterior Abdominal WallMuscles
Rectus Abdominis Origin
Pubic crest, symphysis
Insertion
Xiphoid process, costal cartilages ofribs 5-7
Function
Flex, rotate trunk, fix and depress ribs,stabilize pelvis, compress abdomen
Internal oblique
Origin
Lumbar fascia, iliac crest, inguinalligament
Insertion
Linea alba, pubic crest, last 3-4 ribs,costal margin
Function
Same for external obliques
pg 250,251
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Anterior Abdominal Wall
External oblique Origin
Lower 8 ribs
Insertion Aponeurosis to linea alba, pubic and
iliac crest Function
Flex trunk, compress abdominal wall(together), Rotate trunk (separatesides)
Transversus abdominis
Origin Inguinal ligament, lumbar fascia,
cartilage of last 6 ribs, iliac crest
Insertion Linea alba, pubic crest
Function
Compress abdominal contents
pg249
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Posterior Abdominal Wall Iliopsoas
Psoas major Origin
Lumbar vertebrae, T12
Insertion Lesser trochanter of femur via iliopsoas
tendon
Function
Thigh flexion, trunk flexion, lateral flexion Innervation Ventral rami L1-L3
Iliacus Origin
Iliac fossa, ala of sacrum
Insertion
Lesser trochanter of femur via iliopsoastendon
Function Thigh flexion, trunk flexion
Innervation Femoral nerve (L2 and L3)
Psoas minor variable (40-60% do nothave)pg
316
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Posterior Abdominal Wall
Quadratus lumborum Origin
Iliac crest and lumbar fascia
Insertion
Transverse process of upperlumbar vertebrae, lower marginof rib 12
Function Flex vertebral column, maintains
upright posture, assists ininspiration
Innervation:T12 and upper lumbar spinal
nerves (ventral rami)
pg
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Peritoneum
Mesenteries Double layer of peritoneum (2 serous membranes
fused together)
Extend to the digestive organs from the body wall
Function:Hold organs in place
Sites of fat storage
Provide a route for vessels and nerves
Dorsal mesenteries: Lesser omentum and Falciform ligament
Ventral mesenteries: Greater omentum, Transverse mesocolon, Mesentary, and
Sigmoid mesocolon
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Dorsal Mesenteries
pg 269 pg291
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Ventral Mesenteries
pg 269
pg 271
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Peritoneum
Peritoneal Remains surrounded by peritoneal cavity
Liver, stomach, ileum and jejunum
Retroperitoneal
Some organs lay behind/outside peritoneum Primarily retroperitoneal
Organs NEVER within the cavity
Kidneys, bladder, ureter
Secondarily retroperitoneal Organs once suspended within the abdominal cavity by mesentery
Migrate posterior to the peritoneum during the course ofembryogenesis to become retroperitoneal
Lack mesenteries
Duodenum, ascending and descending colon, rectum, pancreas
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pg 226
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Organs of the Abdomen
Urinary and Digestive
Systems
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Urinary System
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Urinary System
Kidney (2) Purify blood
Ureter (2)
Drains urine fromkidney to bladder
Urinary Bladder Stores urine
Urethra Drains urine from
bladder to outsidebody
pg 314
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Kidneys
Filter waste from blood
Water, toxins, urea, uric acid, creatinine,metabolic waste, ions
Excretion of waste Homeostasis
Acid-base balance
Blood pressure Plasma volume
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Kidneys: Gross Anatomy
Lie in retroperitoneal,superior lumbar region
Extend from T11 or T12to L3
Laterally convex,medially concave
Hilus Where blood vessels,
ureters, and nerves enterand leave kidney
Adrenal gland On superior portion
pg 325
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Kidney: Gross Anatomy
Separated into lobes
Blood supply
Renal artery and vein
hearts systematicoutput reaches the kidney
Innervation
Branches of renal plexus
pg 323
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Kidney: Gross Anatomy
Supportive tissue Renal capsule
DCT Adheres directly to
kidney surface Maintains shape and
forms barrier
Adipose capsule Perirenal fat Cushions kidney
Keeps kidney in place Renal fascia Pararenal fat
Cushions kidney Keeps kidney in place
Internal
External
pg 322
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Kidney: Internal GrossAnatomy
Cortex
Superficial
Lighter zone
Functional portion
Medulla
Deep
Darker zone Pyramid shaped
Contains collectingtubules
pg 323
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Kidney: Internal GrossAnatomy
Medullary pyramid Makes up the medulla
Base: against cortex
Apex: inward Papilla = tip
Drips urine into minor calyx
Calices Collect urine draining from papillae
and empty into renal pelvis
Major calices Branching extensions of renal pelvis
Minor calices Divisions of major calices
Surround papilla of pyramids
Collect urine from papilla Renal pelvis
Expanded superior part of ureterpg 323
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Kidney: Internal Vasculature
Renal arteries
Segmental arteries
Enter through the
hilus Branch into:
Lobar arteries
Interlobar arteries
Arcuate arteries At border of cortex
and medulla
Interlobular arteries
pg 323
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Kidney: MicroscopicAnatomy
Uriniferous tubules
Produces urine through filtration, reabsorption, andsecretion
2 major part:
Nephron Collecting duct
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Ureters
Carry urine from thekidneys to the bladder
Begins superiorly at L2 as acontinuation of renal pelvis
Opens into the bladder Retroperitoneal
Enters the bladder at anoblique angle This prevents backflow into
the ureters
Increased pressure inbladder lead to the distalend of ureter closing Not only gravity at work
here!!
pg 325
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Ureters: MicroscopicAnatomy
Another tubular organ!!
Mucosa Lamina epithelialis
Transitional epithelium
Stretches when ureters
are full Lamina propria
Muscularis Inner longitudinal
Outer circular
External longitudinal layer(inferior third)
Function in peristalsis
Adventitia CT
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Urinary Bladder
Stores and expels urine
Posterolateral angle receivesthe ureter
Inferior angle drains into theurethra
Located: Inferior to peritoneal cavity On pelvic floor
Posterior to pubic symphysis
Male: Anterior to rectum
Female: Anterior to vagina and uterus
pg 400
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Urinary Bladder
Full bladder expandsinto abdominal cavity
Empty bladder lieswithin pelvic cavity
Vasculature:
Internal iliac branches ofarteries and veins
Innervation:
Branches of thehypogastric plexus
pg 399
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Urinary Bladder: InternalAnatomy
Tubular organ!!!!!
Trigone area
3 layers: Mucosa
Transitional epithelium Lamina propria
Muscular layer Detrusor muscle (smooth);
3 layers:
Inner and outerlongitudinal, middle circular
Adventitia Fibrous CT
Parietal peritoneum onsuperior surfacepg 400
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Urethra
Drains urine frombladder to outside ofbody
Female:
Short tube
Male 3 regions
Prostatic urethra
Membranous urethra
Spongy/penile urethra
Opens at the externalurethral orifice
Also carries ejaculatingsemen
pg 400
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Urethra Landmarks
Internal urethral sphincter At bladder/urethral junction
Thickening of detrusor muscle
Involuntary; keeps urethra closed when urine is not beingpassed
Prevents dribbling!
External urethral sphincter Surrounds urethra within the urogenital diaphragm
Inhibits voluntary urination until ready
External urethral orifice Males:
End of the penile urethra
Females: Anterior to vaginal opening and posterior to clitoris
M l F l
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Males versus Females:
pg 403
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Micturition = Urination
Contraction of the detrusor muscle to raise intra-abdominal pressure
Controlled by the brain
Urine accumulation leads to distention of the bladder
Activates stretch receptors Send sensory impulses to micturition center (MC) in the
pons
MC sends signals to parasympathetic neurons Stimulate detrusor muscle to contract (involuntary)
Internal urinary sphincter opens (also inhibits sympatheticpathways that would prevent urination)
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Micturition = Urination
Other brain receptors (pons, cerebralcortex) can inhibit urination
Relaxing of the detrusor, keeping external
urinary sphincter closed
Voluntary contraction of abdominalwall muscles increases abdominal
pressure Voluntary relaxation of external
urethral sphincter
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Digestive System
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Digestive System
Alimentary Canal Mouth
Pharynx
Esophagus
Stomach Small Intestine
Large Intestine
Accessory Organs Teeth, Tongue
Salivary Glands Gallbladder
Liver
Pancreas
pg 222
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Digestive Processes 6Steps
Ingestion Taking food into the mouth
Propulsion Movement of food through GI tract
Swallowing and peristalsis
Mechanical digestion Prepares food for chemical digestion Chewing, churning, segmentation
Chemical digestion Enzymes break down complex food molecules
Absorption
Digested end products from lumen to blood
Defecation Elimination of indigestible substances
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Alimentary Canal Wall
ANOTHER tubular organ!
Layers:
Mucosa
Epithelium
Lamina propria (MALT)
Lamina muscularis mucosa
Submucosa
CT with elastic fibers, nerves,vessels
Muscularis
Inner circular Outer longitudinal
Creates sphincters
Serosa / Adventitiapg 313
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Peristalsis vs Segmentation
Peristalsis
Propulsion
Adjacent segments of the alimentarycanal contract and relax
Moves food distally along the canal
Segmentation
Part of mechanical breakdown
Food-mixing process
Nonadjacent segments of the intestinealternatively contract and relax
Moves food on and back
Mixes rather than propels
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Innervation
Nerve plexuses Occur within wall of alimentary canal
Parasympathetic, Sympathetic, VisceralSensory fibers
2 types: Myenteric nerve plexus
Between 2 muscle layers of the tunica muscularis
Controls segmentation and peristalsis
Submucosal nerve plexus Between submucosa and muscularis mucosa
Signals glands to secrete and LMM to contract
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pg 313
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Innervtion
Enteric Nervous System (ENS) Internal neurons in wall of canal (100 million!!)
Within the above plexuses
Form independent arcs of sensory, intrinsic,and motor neurons
Controls glandular secretion, peristalsis,segmentation
Autonomic Nervous System speeds up orslows activity controlled by enteric systemAllows the CNS to influence it
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Stomach
J-shaped
Temporary storage tank
Regions: Cardiac
Cardiac orifice
Junction of esophagus Fundus
Under diaphragm
Body Large midportion
Pyloric
Ends at the stomach Pyloric sphincter
Greater curvature
Lesser curvature
pg 272
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Stomach Function
Storage of chyme Food paste
Breakdown of food proteins
Done by pepsin Protein-digestion under acidic conditions
Absorption of nutrients H
2O, electrolytes
Alcohol, other drugs Food remains for about 4 hours
Holds from 1.5 to 4 liters
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Small Intestine
Longest portion of GI tract
Site of most enzymatic digestion andabsorption of nutrients Bile: emulsifier (gallbladder, liver)
Enzymes (pancreas)
Undergoes segmentation Allows for an increase contact with intestinal walls
Peristalsis propels chyme through in about 3
to 6 hours 2.6 to 6 meters long!!
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Small Intestine
Location: From pyloric sphincter
to first part of thelarge intestine
Regions: Duodenum (5%)
Proximal
Jejunum (almost 40%) Middle
Ileum (almost 60%) Distal
pg 274
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Small Intestine
Duodenum C shaped Short, straight Mostly retroperitoneal Receives:
Digestive enzymes from pancreasvia main pancreatic duct Bile from liver via the bile duct
Ileum and jejunum Highly coiled Fewer modifications
Hang by mesentery in peritonealcavity Mesentery Arcades
Arteries + veins Nerves Store fat
pg 283
S ll I t ti I t l
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Small Intestine InternalAnatomy
Intestinal flora produces vitamin K
Epithelium: Simple columnar epithelium
with many modifications forabsorption
Lymph tissue in submucosa Muscularis externa has 2 layers
Innervation: Some parasympathetic
innervation from vagus
Arterial supply: Superior mesenteric
Rt (cranial)pancreaticoduodenal
pg 283
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SI Absorption Modifications
Length More length, more area for
absorption!
Circular folds Plicae circulares
Transverse ridges of mucosa
Increase surface area
Force chyme to slow down
Villi Move chyme and increase contact
Contain lacteals
Remove fat
Microvilli More increasing of the surfcae area
Modifications decrease distally
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Large Intestine
Regions:
Cecum
Vermiform appendix
Colon Ascending
Transverse
Descending
Sigmoid
Rectum
Anal Canal
pg 279
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Large Intestine
Functions:
Absorbs remainingnutrients
Most material largelydigested
Absorbs water andelectrolytes
Forms, stores and expels
feces from body Propulsion is slow and weak
through LI except for massperistaltic movements
pg 283
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LI: Internal Features
Intestinal flora
No intestinal villi or modifications forabsorption
Many goblet cells
Simple columnar epithelium except lower halfof anal canal
Significant lymph tissue in mucosa andsubmucosa
Muscularis mucosae has 2 layers
Some parasympathetic innervation fromvagus
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LI Special Features
Teniae coli 3 Longitudinal strips
Thickenings oflongitudinal muscle layer
Maintain muscle tone
Cause LI to pucker intosacs.
Haustra Saclike divisions
Epiploic appendages Fat-filled pouches of
visceral peritoneum
Hang from the intestinepg 279
Cecum and Vermiform
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Cecum and VermiformAppendix
Cecum Sac-like pouch (blind pouch)
Ileocecal valve 2 raised edges of the mucosa
Sphincter keeps closed until
food in stomach Prevents reflux of feces from
cecum to ileum
Vermiform Appendix Blind tube
Opens into cecum Contains large masses of
lymphoid tissue
pg 276
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Colon Segments
Ascending Right side of posterior
abdominal wall Makes right angle turn
Right colic / hepatic flexure
Transverse Extends left across the
peritoneal cavity Bends downward at the
spleen Left colic / splenic flexure
Descending Left side Sigmoid
S-shaped True pelvis
pg
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Colon Functions
Absorb H2O and electrolytes
Some digestion by bacteria
Mass Peristaltic Movements (2-3xday)
Moves through in 12-24 hours
1.5 meters
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Rectum
Joins with the sigmoidcolon
Descends into thepelvis
Complete and well-developed longitudinalmuscle layer
Rectal valves
3 transverse folds Prevent feces from being
passed along with gas
pg 283
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Anal Canal
Begins where rectum passesthrough the levator animuscle
Releases mucus to lubricatefeces
Internal anal sphincter Made of smooth muscle
Involuntary
External anal sphincter Made of skeletal muscle
Voluntary
Toilet training!!!
Stratified squamousepithelium at lower half
pg 398
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Defecation
Stretching of rectal wall initiates defecationreflex
Mediated by the spinal cord Parasympathetic reflex signals walls of sigmoid
colon and rectum to contract and anal sphinctersto relax
Involuntary
If not ready, reflective contraction ends and
rectum relaxes Reflex initiated again until you actually defecate
Contraction of diaphragm, levator ani andabdominal muscles assist Voluntary
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Accessory Digestive
Organs
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Liver
Largest gland in thebody! Weighs about 3 pounds
Highly vascular
Location: Inferior to diaphragm In right superior part of
abdominal cavity
Mostly upper rib cage
Functions: (Over 500!) Produce bile Pick up glucose
Detoxify poison, drugs
Produce blood proteins
pg 242
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Liver Gross Anatomy
2 surfaces: Diaphragmatic
Visceral
Lobes:
Right lobe Left lobe
Divided by: Falciform ligament on
diaphragmatic surface
Fissure on the visceral
surface Quadrate lobe
Caudate lobe Both part of left lobe and
visceral surface
pg 285
pg 287
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Liver Visceral Surface
Hepatic Vein (intoinferior vena cava)
Porta Hepatis
Hepatic Artery (from
abdominal aorta ) Hepatic Portal Vein
Carries nutrient-rich bloodfrom stomach andintestines to liver
Hepatic portal system = 2
capillary beds!
Hepatic Ducts (carry bile)
pg 286
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Gallbladder
Muscular sac Rests in depression of
right liver lobe
Has many ducts
associated with it Stores and
concentrates bile Breaks down fats
Emulsification
Produced in liver
Stored in gallbladder
Secreted in duodenum
pg 285
pg 287
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Gallbladder
Mucosa Simple columnar
epithelium
Lamina propria
Expandable mucosalfolds
Smooth muscle layer
Thick connective
tissue Covered by serosa inplaces
pg 287
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Bile Ducts
Hepatic duct Carries bile from
liver
Cystic duct
Joins hepatic ductfrom liver to formthe bile duct
Carries bile fromgallbladder
Common Bile duct Empties into the
duodenum
pg 289
pg 290
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Movement of Bile
Bile secreted by liver continuously Hepatopancreatic (Vater) ampulla
common bile + main pancreatic duct meetand enter duodenum
Sphincter of Oddi around it closed when bile not needed for digestion
Bile then backs up into gallbladder via cysticduct
When needed gallbladder contracts, sphinctersopen
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Pancreas
Both exocrine andendocrine gland
Exocrine Produce enzymes that
digest food
Endocrine Produce hormones that
regulate blood sugar(insulin and glucagon)
Secondarily
retroperitoneal Location: Curve of duodenum Extends to spleen
pg 288
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Pancreatic Ducts
Main pancreatic duct Extends length of pancreas Joins bile duct to form the hepatopancreatic ampulla Empties into duodenum
Accessory pancreatic duct
Lies in head of pancreas Drains into the main duct Enters duodenum also
pg 289
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Arterial Blood Supply to
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Arterial Blood Supply toAbdominal Viscera
All branches of Abdominal Aorta
Anastomoses
Left + Middle colic
Left + Right gastric Left + Right gastroepiploic
Cranial + Caudal pancreaticoduodenal
Deep Iliac Circumflex + Adrenolumbar
Remember your zoological roots: YOUMUST KNOW WHAT SUPPLIES WHAT!!
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Names give hints!
Hepato = liver
Pancreatico =pancreas
Cystic = gallbladder Gastro = stomach
Splenic = spleen
Adreno = adrenal gl
Lumbar = lumbarregion
Epiploic =membrane-covered
Mesenteric =
mesentery Duodenal =
duodenum
Ileo = ileum
Colic = colon
Rectal = rectum