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Surface Anatomy, Vessels, Muscles, and Peritoneum
The Abdomen Surface Anatomy, Vessels, Muscles, and Peritoneum
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Abdominopelvic Cavity
Ventral body cavity Thoracic Abdominopelvic Abdominal Liver Stomach Kidneys Pelvic cavity Bladder Some reproductive organs Rectum
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Abdominopelvic Cavity
Surrounded by the abdominal walls and pelvic girdle The two cavities are continuous Most organs surrounded by a peritoneal cavity Visceral peritoneum Serous peritoneum Peritoneal cavity pg 242
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Abdominal Quadrants 9 regions 4 quadrants Draw “line” through navel
Right upper quadrant Left upper quadrant Left lower quadrant Right lower quadrant pg 242
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Surface Anatomy Anterior abdominal wall extends from costal margin to 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 process to pubic symphysis pg 345
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Muscles Function: Abdominal wall Help contain abdominal organs
Move trunk Forced breathing Increase intra-abdominal pressure Abdominal wall Anterior (4) Innervated by intercostal nerves Continuous with layers of intercostal muscles Fibers of layers run in different directions for strength Ends in aponeurosis which contains rectus abdominis muscle Posterior (3) pg 250
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Anterior Abdominal Wall Muscles
Rectus Abdominis Origin Pubic crest, symphysis Insertion Xiphoid process, costal cartilages of ribs 5-7 Function Flex, rotate trunk, fix and depress ribs, stabilize pelvis, compress abdomen Internal oblique Lumbar fascia, iliac crest, inguinal ligament Linea alba, pubic crest, last 3-4 ribs, costal margin 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 (separate sides) Transversus abdominis Inguinal ligament, lumbar fascia, cartilage of last 6 ribs, iliac crest Linea alba, pubic crest Compress abdominal contents pg 249
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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 Iliac fossa, ala of sacrum Thigh flexion, trunk flexion Femoral nerve (L2 and L3) Psoas minor – variable (40-60% do not have) pg 316
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Posterior Abdominal Wall
Quadratus lumborum Origin Iliac crest and lumbar fascia Insertion Transverse process of upper lumbar vertebrae, lower margin of rib 12 Function Flex vertebral column, maintains upright posture, assists in inspiration Innervation: T12 and upper lumbar spinal nerves (ventral rami) pg 316
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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 291 pg 269
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Ventral Mesenteries pg 271 pg 269
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Peritoneum Peritoneal Retroperitoneal
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 of embryogenesis to become retroperitoneal Lack mesenteries Duodenum, ascending and descending colon, rectum, pancreas
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pg 226
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Urinary and Digestive Systems
Organs of the Abdomen Urinary and Digestive Systems
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Urinary System
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Urinary System Kidney (2) Ureter (2) Urinary Bladder Urethra
Purify blood Ureter (2) Drains urine from kidney to bladder Urinary Bladder Stores urine Urethra Drains urine from bladder to outside body pg 314
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Kidneys Filter waste from blood Excretion of waste Homeostasis
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 T12 to L3 Laterally convex, medially concave Hilus Where blood vessels, ureters, and nerves enter and leave kidney Adrenal gland On superior portion pg 325
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Kidney: Gross Anatomy Separated into lobes Blood supply Innervation
Renal artery and vein ¼ heart’s systematic output reaches the kidney Innervation Branches of renal plexus pg 323
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Kidney: Gross Anatomy Supportive tissue Renal capsule Adipose capsule
Internal 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 pg 322 External
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Kidney: Internal Gross Anatomy
Cortex Superficial Lighter zone Functional portion Medulla Deep Darker zone Pyramid shaped Contains collecting tubules pg 323
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Kidney: Internal Gross Anatomy
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 ureter pg 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: Microscopic Anatomy
Uriniferous tubules Produces urine through filtration, reabsorption, and secretion 2 major part: Nephron Collecting duct
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Ureters Carry urine from the kidneys to the bladder
Begins superiorly at L2 as a continuation of renal pelvis Opens into the bladder Retroperitoneal Enters the bladder at an oblique angle This prevents backflow into the ureters Increased pressure in bladder lead to the distal end of ureter closing Not only gravity at work here!! pg 325
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Ureters: Microscopic Anatomy
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 receives the ureter Inferior angle drains into the urethra 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 expands into abdominal cavity
Empty bladder lies within pelvic cavity Vasculature: Internal iliac branches of arteries and veins Innervation: Branches of the hypogastric plexus pg 399
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Urinary Bladder: Internal Anatomy
Tubular organ!!!!! Trigone area 3 layers: Mucosa Transitional epithelium Lamina propria Muscular layer Detrusor muscle (smooth); layers: Inner and outer longitudinal, middle circular Adventitia Fibrous CT Parietal peritoneum on superior surface pg 400
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Urethra Drains urine from bladder to outside of body Female: Male
Short tube Male 3 regions Prostatic urethra Membranous urethra Spongy/penile urethra Opens at the external urethral orifice Also carries ejaculating semen 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 being passed 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
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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 sympathetic pathways that would prevent urination)
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Micturition = Urination
Other brain receptors (pons, cerebral cortex) can inhibit urination Relaxing of the detrusor, keeping external urinary sphincter closed Voluntary contraction of abdominal wall muscles increases abdominal pressure Voluntary relaxation of external urethral sphincter
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Digestive System
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Digestive System Alimentary Canal Accessory Organs 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 – 6 Steps
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 Submucosa
Epithelium Lamina propria (MALT) Lamina muscularis mucosa Submucosa CT with elastic fibers, nerves, vessels Muscularis Inner circular Outer longitudinal Creates sphincters Serosa / Adventitia pg 313
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Peristalsis vs Segmentation
Propulsion Adjacent segments of the alimentary canal contract and relax Moves food distally along the canal Segmentation Part of mechanical breakdown Food-mixing process Nonadjacent segments of the intestine alternatively 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, Visceral Sensory 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 or slows activity controlled by enteric system Allows the CNS to influence it
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Stomach J-shaped Temporary storage tank Regions: Cardiac Fundus Body
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 – Internal Anatomy
Mucosa Epithelium Simple columnar Rugae Folds that allow for volume changes Intrinsic glands Goblet cells Gastric glands Submucosa Muscularis Oblique layer Circular layer Pyloric sphincter Longitudinal layer Serosa
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Stomach Function Storage of chyme Breakdown of food proteins
Food paste Breakdown of food proteins Done by pepsin Protein-digestion under acidic conditions Absorption of nutrients H2O, 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 and absorption 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: Regions:
From pyloric sphincter to first part of the large intestine Regions: Duodenum (5%) Proximal Jejunum (almost 40%) Middle Ileum (almost 60%) Distal pg 274
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Small Intestine Duodenum Ileum and jejunum C – shaped Short, straight
Mostly retroperitoneal Receives: Digestive enzymes from pancreas via main pancreatic duct Bile from liver via the bile duct Ileum and jejunum Highly coiled Fewer modifications Hang by mesentery in peritoneal cavity Mesentery Arcades Arteries + veins Nerves Store fat pg 283
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Small Intestine Internal Anatomy
Intestinal flora produces vitamin K Epithelium: Simple columnar epithelium with many modifications for absorption 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 Rectum
Ascending Transverse Descending Sigmoid Rectum Anal Canal pg 279
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Large Intestine Functions: Absorbs remaining nutrients
Most material largely digested Absorbs water and electrolytes Forms, stores and expels feces from body Propulsion is slow and weak through LI except for mass peristaltic movements pg 283
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LI: Internal Features Intestinal flora
No intestinal villi or modifications for absorption Many goblet cells Simple columnar epithelium except lower half of anal canal Significant lymph tissue in mucosa and submucosa Muscularis mucosae has 2 layers Some parasympathetic innervation from vagus
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LI Special Features Teniae coli Haustra Epiploic appendages
3 Longitudinal strips Thickenings of longitudinal muscle layer Maintain muscle tone Cause LI to pucker into sacs……. Haustra Saclike divisions Epiploic appendages Fat-filled pouches of visceral peritoneum Hang from the intestine pg 279
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Cecum and Vermiform Appendix
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 Transverse Descending Sigmoid
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 279
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Colon Functions Absorb H2O and electrolytes Some digestion by bacteria
Mass Peristaltic Movements (2-3x day) Moves through in hours 1.5 meters
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Rectum Joins with the sigmoid colon Descends into the pelvis
Complete and well-developed longitudinal muscle 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 passes through the levator ani muscle
Releases mucus to lubricate feces Internal anal sphincter Made of smooth muscle Involuntary External anal sphincter Made of skeletal muscle Voluntary Toilet training!!! Stratified squamous epithelium at lower half pg 398
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Defecation Stretching of rectal wall initiates defecation reflex
Mediated by the spinal cord Parasympathetic reflex signals walls of sigmoid colon and rectum to contract and anal sphincters to relax Involuntary If not ready, reflective contraction ends and rectum relaxes Reflex initiated again until you actually defecate Contraction of diaphragm, levator ani and abdominal muscles assist Voluntary
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Accessory Digestive Organs
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Liver Largest gland in the body! Highly vascular Location:
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: Lobes: Diaphragmatic Visceral
pg 285 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 287
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Liver – Visceral Surface
pg 286 Hepatic Vein (into inferior vena cava) Porta Hepatis Hepatic Artery (from abdominal aorta ) Hepatic Portal Vein Carries nutrient-rich blood from stomach and intestines to liver Hepatic portal system = 2 capillary beds! Hepatic Ducts (carry bile)
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Gallbladder Muscular sac Rests in depression of right liver lobe
pg 285 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 287
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Gallbladder Mucosa Smooth muscle layer Thick connective tissue
Simple columnar epithelium Lamina propria Expandable mucosal folds Smooth muscle layer Thick connective tissue Covered by serosa in places pg 287
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Bile Ducts Hepatic duct Cystic duct Common Bile duct
Carries bile from liver Cystic duct Joins hepatic duct from liver to form the bile duct Carries bile from gallbladder 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 meet and enter duodenum Sphincter of Oddi around it closed when bile not needed for digestion Bile then backs up into gallbladder via cystic duct When needed gallbladder contracts, sphincters open
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Pancreas Both exocrine and endocrine gland Exocrine Endocrine
pg 288 Both exocrine and endocrine 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
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Pancreatic Ducts Main pancreatic duct Accessory 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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Spleen Largest lymphoid organ Location: Highly vascular Function:
Left superior quadrant of abdominal cavity Posterior to stomach Highly vascular Function: Removes blood-borne antigens Removes and destructs aged blood cells Site of hematopoiesis in fetus Stores blood platelets pg 297
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Arterial Blood Supply to Abdominal 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: YOU MUST 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 = lumbar region Epiploic = membrane-covered Mesenteric = mesentery Duodenal = duodenum Ileo = ileum Colic = colon Rectal = rectum
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