Surface Anatomy, Vessels, Muscles, and Peritoneum The Abdomen Surface Anatomy, Vessels, Muscles, and Peritoneum

Abdominopelvic Cavity Ventral body cavity Thoracic Abdominopelvic Abdominal Liver Stomach Kidneys Pelvic cavity Bladder Some reproductive organs Rectum www.templejc.edu

Abdominopelvic Cavity Surrounded by the abdominal walls and pelvic girdle The two cavities are continuous Most organs surrounded by a peritoneal cavity Visceral peritoneum Parietal peritoneum Peritoneal cavity pg 254

Abdominal Quadrants 9 regions 4 quadrants Draw “line” through navel Right upper quadrant Left upper quadrant Left lower quadrant Right lower quadrant pg 268

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 383

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 276

Anterior Abdominal Wall Muscles 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) Internal oblique Lumbar fascia, iliac crest, inguinal ligament Linea alba, pubic crest, last 3-4 ribs, costal margin Same for external obliques pg 276, 277

Anterior Abdominal Wall pg 276 pg 275 Transversus Abdominis Origin Inguinal ligament, lumbar fascia, cartilage of last 6 ribs, iliac crest Insertion Linea alba, pubic crest Function Compress abdominal contents Rectus Abdominis Pubic crest, symphysis Xiphoid process, costal cartilages of ribs 5-7 Flex, rotate trunk, fix and depress ribs, stabilize pelvis, compress abdomen

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 350

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 350

Peritoneum Mesenteries Function: Ventral 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 Ventral mesenteries: Lesser omentum and Falciform ligament Dorsal mesenteries: Greater omentum, Transverse mesocolon, Mesentery proper, and Sigmoid mesocolon pg 296 pg 324 pg 295, 297

Peritoneum Intraperitoneal Retroperitoneal Organs remain surrounded by peritoneal cavity Liver, stomach, ileum and jejunum, transverse colon 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

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 341

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

Kidneys: Gross Anatomy Lie in retroperitoneal, superior lumbar region Extend from T11 or T12 to L3 Laterally convex, medially concave Hilum Where blood vessels, ureters, and nerves enter and leave kidney Adrenal gland On superior portion Endocrine Cortisol Aldosterone Adrenaline pg 360

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 357 External

Kidney: Internal Gross Anatomy Cortex Superficial Lighter zone Functional portion Medulla Deep Darker zone Pyramid shaped Contains collecting tubules pg 358

Kidney: Gross Anatomy Separated into lobes Blood supply Innervation Medulla pyramid & associated cortex Blood supply Renal artery and vein Innervation Branches of renal plexus pg 358

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 Minor calices Collect urine from papilla Surround papilla of pyramids Empty into major calices Major calices Receive urine from several minor calices Empty into renal pelvis Renal pelvis Funnel-shaped Empties urine into ureter pg 358

Kidney: Microscopic Anatomy Uriniferous tubules Produces urine through filtration, reabsorption, and secretion 2 major part: Nephron Collecting duct www.uptodate.com

Ureters Carry urine from the kidneys to the bladder www.incostress.com 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 360

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 faculty.une.edu

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 442

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 441

Urinary Bladder: Internal Anatomy Tubular organ!!!!! Trigone area 3 layers: Mucosa Transitional epithelium Lamina propria Muscular layer Detrusor muscle (smooth); Inner and outer longitudinal, middle circular Adventitia Fibrous CT Parietal peritoneum on superior surface pg 442

Urethra Drains urine from bladder to outside of body Opens at the external urethral orifice Female: Short tube Male 3 regions Prostatic urethra Membranous urethra Spongy/penile urethra Also carries ejaculating semen pg 442

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 pg 445

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)

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

Digestive System Alimentary Canal Accessory Organs Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine Accessory Organs Teeth, Tongue Salivary Glands Gallbladder Liver Pancreas pg 248

Digestive Processes – 6 Steps Ingestion Taking food into the mouth Mechanical digestion Prepares food for chemical digestion Chewing, churning, segmentation Propulsion Movement of food through GI tract Swallowing and peristalsis Chemical digestion Enzymes break down complex food molecules Absorption Digested end products from lumen to blood Defecation Elimination of indigestible substances

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 347

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 www.answers.com www.3dscience.com

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

Innervation 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 pg 313

Stomach J-shaped, Temporary storage tank Intraperitoneal 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 299

Stomach – Internal Anatomy www.acm.uiuc.edu Mucosa Epithelium Simple columnar Rugae Folds that allow for volume changes Intrinsic glands Goblet cells Gastric glands Parietal cells Enteroendocrine cells Chief cells Submucosa Muscularis Oblique layer Circular layer Pyloric sphincter Longitudinal layer Serosa

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

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!!

Small Intestine Location: Regions: www.nlm.nih.gov Location: From pyloric sphincter to first part of the large intestine Regions: Duodenum (5%) Proximal Jejunum (almost 40%) Middle Ileum (almost 55%) Distal pg 300

Small Intestine Duodenum Jejunum and ileum Duodenal glands: C – shaped , short, straight Mostly retroperitoneal Receives: Digestive enzymes from pancreas via main pancreatic duct Bile from liver via the bile duct Duodenal glands: Neutralize acid from stomach Jejunum and ileum Highly coiled Intraperitoneal Fewer modifications Hang by mesentery in peritoneal cavity Mesentery Arcades Arteries + veins Nerves Store fat www.si.mahidol.ac.th

Small Intestine Internal Anatomy Intestinal flora produces vitamin K Epithelium: Simple columnar epithelium with many modifications for absorption Goblet cells Enteroendocrine cells Lymph tissue in submucosa Muscularis externa has 2 layers Innervation: Some parasympathetic innervation from vagus Arterial supply: Superior mesenteric Rt (cranial) pancreaticoduodenal pg 311

SI Absorption Modifications www.siumed.edu www.cartage.org.lb Length More length, more area for absorption! Plicae Circulares Transverse ridges of mucosa Increase surface area Force chyme to slow down Villi Evagination of plicae circulares Move chyme and increase contact Contain lacteals Remove fat Microvilli Further increasing of the surface area Modifications decrease distally

Large Intestine Regions: Cecum Vermiform appendix Colon Rectum Ascending Transverse Descending Sigmoid Rectum Anal Canal pg 311

Large Intestine Overall 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

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

Cecum and Vermiform Appendix Sac-like pouch (blind pouch) Intraperitoneal Ileocecal valve 2 raised edges of the mucosa Prevents reflux of feces from cecum to ileum Vermiform Appendix Tubular pouch Opens into cecum Contains large masses of lymphoid tissue assets.aarp.org pg 302

Colon Special Features Teniae coli 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

Colon Segments Ascending Transverse Descending Sigmoid Retroperitoneal Right side of posterior abdominal wall Makes right angle turn Right colic / hepatic flexure Transverse Intraperitoneal Extends left across the peritoneal cavity Bends downward at the spleen Left colic / splenic flexure Descending Left side Sigmoid S-shaped “False pelvis” pg 311

Colon Functions Absorb H2O and electrolytes Some digestion by bacteria Mass Peristaltic Movements (2-3x day) Moves through in 12-24 hours 1.5 meters

Rectum Joins with the sigmoid colon Descends into the pelvis Retroperitoneal Complete and well-developed longitudinal muscle layer Rectal valves 3 transverse folds Prevent feces from being passed along with gas pg 312

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 440

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 sphincter 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

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 under rib cage Functions: (Over 500!) Produce bile Pick up glucose Detoxify poison, drugs Produce blood proteins pg 268

Liver Gross Anatomy 2 surfaces: Lobes: Diaphragmatic Visceral pg 317 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 pg 318

Liver – Visceral Surface Hepatic Vein (into inferior vena cava) Porta Hepatis Common Hepatic Artery (from celiac trunk) Hepatic Portal Vein Carries nutrient-rich blood from stomach and intestines to liver Hepatic portal system = 2 capillary beds! Hepatic Ducts (carry bile) pg 318

Gallbladder Muscular sac Rests in depression of right liver lobe pg 317 Muscular sac Rests in depression of right liver lobe Has many ducts associated with it Stores and concentrates bile Emulsification Produced in liver Stored in gallbladder Released into the duodenum pg 319

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 319

Bile Ducts Hepatic duct Cystic duct Common Bile duct pg 321 pg 323 Hepatic 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

Movement of Bile Bile secreted by liver continuously pg 321 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

Pancreas Both exocrine and endocrine gland Exocrine Endocrine pg 320 Both exocrine and endocrine gland Exocrine Produce enzymes that digest food Endocrine Produce hormones that regulate blood sugar (insulin and glucagon) Secondarily retroperitoneal (mostly) Location: Curve of duodenum Extends to spleen

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 pg 321

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 331

Arterial Blood Supply to Abdominal Viscera All branches of Abdominal Aorta Anastomoses Left + Middle colic Left + Right gastric Left + Right gastroepiploic Cranial + Caudal pancreaticoduodenal Remember your zoological roots: YOU MUST KNOW WHAT SUPPLIES WHAT!!

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