Abdomen PDF - Human Anatomy

Advanced Human Anatomy and Histology Abdomen Bellyache Robert Burton, 1621 Billie Eilish Boundaries of the Abdomen Superior ‒ Limited by the diaphragm Lateral / Anterior walls ‒ Abdominal muscles Poster...

Advanced Human Anatomy and Histology Abdomen Bellyache Robert Burton, 1621 Billie Eilish Boundaries of the Abdomen Superior ‒ Limited by the diaphragm Lateral / Anterior walls ‒ Abdominal muscles Posterior wall ‒ Thoracic and lumbar spine ‒ Musculature of abdomen and back Inferior ‒ Communication with the pelvic cavity ‒ Infection in one region can easily spread to the other General Description of the Abdomen Houses and protects major visceral organs Contains: GI tract – stomach, liver, gall bladder, intestine, colon, appendix Spleen Portion of urinary system – kidneys, ureter Adrenal glands Blood vessels – aorta, inferior vena cava Lymphatics Contains the peritoneum, a membranous sheet of connective tissue Abdominal Organs Anterior organs Posterior organs Gray’s Anatomy  Abdominal Organization: Naming Regions 9-region system ‒ Superior regions Epigastric (Center) Right and Left hypochondrium ‒ Middle regions Umbilical (Center) Right and left lumbar ‒ Inferior regions hypogastric (Center) Right and left Abdominal Organization: Naming Regions 4-quadrant system ‒ Right upper ‒ Left upper ‒ Right lower ‒ Left lower Pathology by Quadrant Superior Abdomen Boundary: Diaphragm Central tendon Striated muscle Costal cartilage Foramen Caval – T8, passes the inferior vena cava, right phrenic nerve Esophogeal – T10, passes the esophagus, gastric nerve, gastric blood vessels Aortic – T12, formed by arcuate ligament, left of midline, passes the aorta, thoracic duct, azygous, hemiazygous, splanchnic nerve Ligaments Median arcuate ligament Medial arcuate ligament Lateral arcuate ligament Crus Tendinous structures from diaphragm to vertebral column Form a tether for muscle contraction Right and left crus meet in midline to form the median arcuate ligament (part of aortic foramen) Lateral Abdominal Wall Three layers to lateral abdominal wall External oblique (most external) Internal oblique (middle) Transverse abdominal (most internal) Extend between the vertebral column, the lower ribs, the iliac crest and pubis of the hip Fibers merge towards the midline and surround the rectus abdominis in a sheath before joining up on the opposite side at the linea alba Gray’s Anatomy Lateral Abdominal Wall Muscles External oblique (most external) Origin: Lower 8 costal segments Insertion: Iliac Crest Action: Oppose side torso rotation Internal oblique (middle) Origin: iliac crest, inguinal ligament Inservtion: Inferior costal margin, linea alba Action: same side torso rotation Transverse abdominis (most internal) Part of both the lateral and anterior walls Origin: iliac crest, inguinal ligament Insertion: linea alba, xyphoid process Action: compress Abdomen Anterior Abdominal Wall Rectus abdominus muscle (left and right) Joined by linea alba centrally Origin: the pubis (linea alba more specifically) Insertion: costal segments, xyphoid process Action: lumbar flexion, active respiration Linea alba Fibrous midline structure Runs from xiphoid process to pubic symphysis Posterior Abdominal Wall Made up of muscles that pass through the inferior boundary going from the femur to the abdomen. Pass through from underneath the inguinal ligament Three muscles make up the posterior wall of the abdomen and are also the major muscles that aid in posture Iliacus: runs from iliac crest and fills pelvic bone concavity, attaches to the head of femur Psoas: originates from vertebral bodies, inserts on head of femur; responsible for moving the lower portion of the top torso Quadratus Lumborum: originates from iliac crest and inserts to several vertebral bodies in the lumbar spine, involved with the flexing of the vertebral column, but with the help of other muscles it depresses the thoracic cage Thoracic and Abdominal Contents Sobotta's Atlas and Text-book of Human Anatomy 1906 Abdominal Peritoneum Large serous membrane lining the cavity of the abdomen and covering the abdominal organs Composed of a layer of mesothelium supported by a thin layer of connective tissue Simple squamous epithelium derived from mesoderm Forms the lining of the lungs, heart, abdomen, and testes One continuous sheet that folds into 2 layers forming the peritoneal cavity Pareital peritoneum Visceral peritoneum Intraperitoneal space - located within the abdominal cavity, and covered in peritoneum Retroperitoneal space – structures in the abdominal cavity that are located behind the intraperitoneal space Red: parietal peritoneum Purple: visceral peritoneum Green: omentum Yellow: mesentary Fuschia: retroperitoneal Pink shaded: greater sac Blue shaded: lesser sac Abdominal Peritoneum Peritoneal Folds - connect organs to each other or to the abdominal wall Omenta Mesenteries Two main regions of the peritoneal cavity Greater sac (pink in previous slide) Lesser sac aka omentum bursa (blue in previous slide) – divided into two omenta (folds of visceral peritoneum) Greater omentum - attaches greater curve of stomach to transverse colon Lesser omentum – attaches lesser curve of stomach to liver Abdominal Peritoneum Visceral peritoneum ‒ Envelops visceral organs Parietal peritoneum ‒ Lines the interior abdominal wall Mesentery ‒ Lies between two peritoneal cavities ‒ Suspensory structure ‒ Conveys vasculature and nerves Peritoneal cavity ‒ Space enveloped in peritoneum Organs lined with peritoneum are called ‘intraperitoneal’ Retroperitoneal space ‒ Deep to the visceral peritoneum  Mesenteries Peritoneal folds that connect organs to each other or to the abdominal wall Continuous set of tissues, formed by the double fold of peritoneum Attaches the stomach, small intestine, spleen, and other organs to the posterior wall of the abdomen Aids in storing fat, provides conduit for blood vessels, lymphatics, and nerves Omentum Also from peritoneum, structurally similar to mesentery Attaches the stomach to another viscus Lesser sac aka omentum bursa – divided into two omenta (folds of visceral peritoneum) Greater omentum - attaches greater curve of stomach to transverse colon Lesser omentum – attaches lesser curve of stomach to liver Intraperitoneal vs Retroperitoneal Intraperitoneal - stomach, spleen, liver, bulb of the duodenum, jejunum, ileum, transverse colon, and sigmoid colon Retroperioneal – Suprarenal glands, abdominal aorta, inferior vena cava, remainder of the duodenum, pancreas, ureters, the cecum and ascending and descending colon, kidneys, esophagus, rectum (SAD PUCKER) S = Suprarenal (adrenal) glands A = Aorta/Inferior Vena Cava D = Duodenum (second and third segments) P = Pancreas U = Ureters C = Colon (ascending and descending only) K = Kidneys E = Esophagus R = Rectum Clinical cases: Abdominal Adhesions Bands of fibrous tissue that can form between abdominal tissues and organs Scar tissue results from previous surgical procedures, infection, trauma, or radiation Can be asymptomatic, or lead to severe abdominal pain or cramping, vomiting, bloating, obstruction, constipation May need surgical treatment Clinical Cases: Ascites Accumulation of fluid in the peritoneal cavity, causing abdominal swelling Normal fluid volume of peritoneal sac is 50 mL, can increase to over several liters (up to 35 L possible) Most common cause is liver cirrhosis, other causes include cancer, heart failure, tuberculosis, pancreatitis, and blockage of the hepatic vein Arterial Circulation of the Abdomen Abdominal aorta ‒ Continuation of the thoracic aorta inferior to the diaphragm ‒ Located left of midline Parietal Branches ‒ Lumbar aa. ‒ Median sacral a. Visceral Branches ‒ Inferior phrenic aa. ‒ Celiac trunk ‒ Superior mesenteric a. ‒ Middle suprarenal aa. ‒ Renal aa. ‒ Testicular / ovarian aa. ‒ Inferior mesenteric a. Terminal Branches ‒ Common iliac aa. ‒ Internal iliac a. ‒ External iliac a. (distally: femoral a.) Arterial Circulation of the Abdomen Geekymedics.com Abdominal Regions: Arterial Supply Celiac trunk supplies the foregut ‒ Liver ‒ Gallbladder ‒ Stomach ‒ Spleen ‒ Pancreas Superior mesenteric a. supplies the midgut ‒ Small intestine ‒ Appendix ‒ Part of the colon (ascending, first part of transverse) Inferior mesenteric a. supplies the hindgut ‒ Part of colon (last part of transverse, descending, sigmoid) ‒ Rectum Celiac Trunk: Foregut Left gastric a. (smallest): stomach Splenic a. (largest): spleen, tail of pancreas, stomach left gastro-omental Common hepatic a. ‒ Right gastric a.: Stomach ‒ Hepatic a. proper: Liver/gallbladder ‒ Gastroduodenal a.: Liver Duodenum Right gastro-omental a. Spleen anastomses with left gastro-omental (branch of splenic a.) Celiac Trunk: Foregut Celiac Trunk: Foregut Atlas of Anatomy , 1st edition (Thieme) Superior Mesenteric Artery: Midgut Pancreaticoduodenal a. - Pancreas and Duodenum (first section of small intestine) Jejunal a. - Jejunum (second section of small intestine) Ileal a. - Ileum (third section of small intestine) Ileocolic a. - Cecum, appendix (first section of large intestine) R. colic a. - Ascending colon (second section of large intestine) Middle colic a. - Transverse colon (first part only; third section of large intestine) Inferior Mesenteric Artery: Hindgut Smallest of the 3 GI branches Branches from abdominal aorta at level L3 Left colic a. - Transverse colon (last part) and descending colon (fourth section of large intestine) Sigmoid aa. - Sigmoid colon (fifth section of large intestine) Superior rectal a. - Rectum (last section of large intestine) Branches of Abdominal Aorta Superior *Inferior phrenic (2) suprarenal (2) *Left Gastric *Celiac Trunk (1) *Splenic Pancreatic Right gastric Middle suprarenal *Common hepatic (2) *Hepatic artery proper Gastroduodenal *Right hepatic *Left hepatic *Renal (2) Inferior supraenal (2) Pancreaticoduodenal *Superior Middle colic mesenteric (1) Right colic *Gonadal (2) Left colic jejunal ileocolic *Lumbar (many) ileal *Inferior Sigmoid mesenteric (1) Superior rectal *R & L *Internal iliac common iliac *Median sacral (1) *External iliac *Femoral  Abdominal Venous Schematic Two abdominal venous systems ‒ Caval: Renal + pelvis + lower limbs → inferior vena cava ‒ Portal: GI Organs + Spleen → hepatic portal v. → liver → hepatic v. → inferior vena cava (this is called portal circulation) Organs of caval system ‒ Urinary organs ‒ Genital organs ‒ Suprarenal glands ‒ Abdominal walls ‒ Pelvis ‒ Lower Limbs Organs of portal system ‒ Hollow organs ▪ Stomach ▪ Small Intestine ▪ Large Intestine ‒ Solid Organs ▪ Pancreas ▪ Liver ▪ Gallbladder ▪ Spleen Tributaries of the Inferior Vena Cava Common iliac v. Median sacral v. Lumbar v. (some) ‒ Potential collateral with azygous v. Right gonadal v. Renal v. ‒ Left suprarenal v. ‒ Left gonadal v. Right suprarenal v. Hepatic vv. (~3 of them) Inferior phrenic v. Hepatic Portal System Responsible for directing blood from parts of the gastrointestinal tract to the liver Raw nutrients in blood are processed before the blood returns to the heart Extends from the lower portion of the esophagus to the upper part of the anal canal, also includes venous drainage from the spleen and pancreas Total liver blood flow is quite high, on average one fourth of the average cardiac output at rest Large veins that are considered part of the portal venous system are the: Hepatic portal vein Splenic vein Superior mesenteric vein Inferior mesenteric vein Hepatic Portal System Collects nutrients, hormones, drugs, alcohol, pathogens from gut to process in liver – first pass metabolism Carries oxygen poor blood Vessels of the organs of the GI tract, spleen, and pancreas drain to the portal system Portal vein does not contain valves, blood moves down a pressure gradient Tributaries of the Hepatic Portal Vein Superior mesenteric v. ‒ Small intestine ‒ Cecum ‒ Ascending colon ‒ Transverse colon Inferior mesenteric v. ‒ Descending colon ‒ Sigmoid colon ‒ Rectum Atlas of Anatomy, 1st edition (Thieme) Tributaries of the Hepatic Portal Vein Pancreaticoduodenal v ‒ Carries insulin and other hormones to liver Splenic v. ‒ Spleen ‒ Removes old RBCs, bilirubin Right and left gastric vv ‒ Stomach (lesser curvature) ‒ Absorbs lipid soluble substances like aspirin and alcohol Atlas of Anatomy, 1st edition (Thieme) Portal Drainage Right gastric Left gastric Pancreaticoduodenal Portal Vein Portal hepatic venules Superior mesenteric Sinusoidal capillaries Inferior phrenic Inferior mesenteric Splenic Central veins Right Left suprarenal suprarenal Hepatic veins Left gonadal Renal Inferior vena cava Right gonadal Lumbar Median sacral Common iliac Caval Drainage Portal and Caval Drainage Portal-Systemic Anastamose Three locations have drainage to both the caval system and portal system Esophagus Rectum Abdominal wall Restricted blood flow in liver, such as in cirrhosis and portal hypertension, can cause back-up in portal system leading to esophageal varices, hemorrhoids, and caput medusae (gut, butt, and caput) Blood Supply to Liver Portal vein Provides 75% of blood supply to liver Confluence of veins from gut Oxygen poor blood Hepatic artery Provides 25% of blood supply to liver Branch of celiac trunk Oxygen rich blood  Liver Porta hepatis ‒ Hepatic artery ‒ Portal vein ‒ Common hepatic duct ‒ Left hepatic duct ‒ Right hepatic duct ‒ Other structures ‒ Hepatic nerve plexus ‒ Parasympathetic from CN X ‒ Sympathetic from celiac ganglion ‒ Lymphatics  Liver Classic Lobule Hepatic artery Bile duct Portal vein Bile duct Small intestine Portal triad Central vein Hepatic vein Inferior vena cava Liver Lobule Gallbladder Storage for accumulated bile ‒ Transported from portal triads via bile ducts ‒ To right and left hepatic ducts ‒ Lumen consists of simple columnar epithelium Route of Secretion: cystic duct → common bile duct (cystic joins with common hepatic duct) → duodenum (merges with main pancreatic duct) Mode of secretion ‒ Muscular contraction of gallbladder and common bile duct. ‒ Relaxation of hepato-pancreatic ampulla and sphincter of common bile duct ‒ Initiated by acid or fat in duodenum ‒ Bile salts reabsorbed by ileum Atlas of Anatomy, 2nd edition (Thieme) Gallbladder Bile - dark green fluid produced by the liver that aids the digestion of lipids in the small intestine About 400 to 800 ml of bile is produced per day in adult human beings Abdominal Innervation Sympathetic Plexus Ganglia Abdominal Lymph Trunks Atlas of Anatomy, 1st edition (Thieme) Spleen Located in the upper left quadrant of the abdomen, but not part of the GI tract Large spongy lymphoid organ ‒ Typically softball-size Thin outer capsule Part of reticuloendothelial system Functions ‒ Production of immunological response to blood borne antigens ‒ Filters RBC’s and particulate matter from blood ‒ Produces RBC’s in fetus and diseased adults Pancreas Morphology ‒ Head (proximal to duodenum), uncinated process, neck, body, and tail ‒ Lobular units Pancreatic duct ‒ Joins with common bile duct Accessory duct ‒ Connection with duodenum above hepatopancreatic ampulla Exocrine function ‒ Predominant tissue ‒ Digestive enzyme secretion ‒ Bicarbonate secretion Endocrine function ‒ Hormone secretion Atlas of Anatomy, 2nd edition (Thieme)  Gastrointestinal System The GI tract from the mouth to anus is about 30 feet Humans produce 1-2 liters of saliva per day Surface area of the small intestine is 2,700 feet Humans have over 400 different species of bacteria in their colon The entire intestinal tract is sterile at birth Hydrochloric acid, produced by the stomach, can dissolve metal but has no effect on plastic The average American adult eats roughly 2,000 lbs of food a year Sword swallowers can insert the blade down the esophagus and to the bottom of the stomach Which food best represents the human body? Gastrointestinal System Ingestion Digestion Absorption Excretion  Gastrointestinal Tract Four layer organization (innermost to outermost layer) ‒ Mucosa (tunica mucosa) ▪ Muscularis mucosae ▪ Lamina propria ▪ Epithelium (SSNK or simple columnar depending on location) ‒ Submucosa ▪ Submucosal plexus ▪ Connective tissue, exocrine glands, lymphatics, vasculature ‒ Muscularis externa Lumen ▪ Outer longitudinal muscle ▪ Myenteric plexus ▪ Inner circular muscle ‒ Serosa (visceral peritoneum) / Adventitia Esophagus Vascular supply ‒ Superior: Inferior thyroid a. and v. ‒ Middle (thoracic): Bronchial and esophageal aa. and azygous, hemiazygous, and accessory hemiazygous vv. ‒ Abdominal (portion inferior to diaphragm): left gastric a. and v. (one of three main branches of celiac trunk) Innervation ‒ Sympathetic: Thoracic plexus ‒ Parasympathetic : Vagus nerve (CN X) ▪ Left vagus - Primarily to anterior vagal trunk ▪ Right vagus - Primarily to posterior vagal trunk ▪ Trunks contribute to esophageal plexus Esophagus Layers ‒ Tunica mucosa (innermost) ▪ Stratified squamous epithelium ▪ Lamina propria: Vessels & Lymphoid aggregates (Ly) Atlas of Anatomy, 1st ▪ Muscularis mucosae (MM) edition (Thieme) ‒ Submucosa (SM) ▪ Loose, distensible, elastic fibers ▪ Seromucous exocrine glands (G) ‒ Muscular externa ▪ Circular muscle ▪ Longitudinal muscle ‒ Serosa/Adventitia (outermost) ▪ Adventitia = Retroperitoneal Wheater’s Functional Histology, 6th edition Gastro-esophageal Junction Sharp mucosal transition from stratified squamous in the esophagus to simple columnar in the stomach Stratified sq. e. (P) Glandular secretory mucosa (M) Muscularis mucosae (MM) Submucosa (SM) Muscular Layer (MP) Wheater’s Functional Histology, 6th edition Gastro-Esophageal Junction Stomach Regions ‒ Fundus ‒ Cardia ‒ Body ‒ Pylorus ‒ Pyloric sphincter Musculature (muscularis externa) ‒ Longitudinal (outer) ‒ Circular (middle) ‒ Oblique (inner) Structures ‒ Rugal folds  Stomach: Gastric Fundus & Body Mucosa Organized into gastric pits Surface-secreting mucus cells (protection of stomach lining) Straight tubular glands ‒ Production of gastric juice ‒ Gastric juice = HCl + Pepsin (hydrolyzes proteins) 7 glands may supply 1 gastric pit (foveola) ‒ Parietal cells (P) ▪ Gastric acid (primarily HCl) ‒ Peptic cells (Pc) ▪ Pepsin ‒ Neuroendocrine ▪ Serotonin, etc. Wheater’s Functional Histology, 6th edition Stomach: Pyloric Body Mucosa Branched and coiled secretory glands Gastric Pits occupy 50% of mucosa (P) G-cells (G) ‒ Secrete gastrin ‒ Stimulates further secretion of HCl ‒ Increases motility ‒ Neuroendocrine cells Muscularis mucosa prominent Gastroduodenal Junction Demarcated by pyloric sphincter (PS) 2-3 mm in diameter Contraction expels food into duodenum Wheater’s Functional Histology, 6th edition Small Intestine Variable length – 10-34 feet (avg 22) Diameter - 3 cm Three sections ‒ Duodenum (8 in) ‒ Jejunum (8 feet) ‒ Ilium (10 feet) Atlas of Anatomy, 1st edition (Thieme) Small Intestine Digestion (duodenum; first 1 m of jejunum) Absorption (differs by region) Surface area maximized ‒ Kerckring’s folds ‒ Villi (long in jejunum; short in ileum) ‒ Microvilli Simple columnar epithelium Wheater’s Functional Histology, 6th edition Duodenum Short segment Neutralize gastric secretions Mucosal layer changes ‒ Prominent villi (more than jejunum or ileum) Brunner’s glands Return to 2-layered muscular externa (inner circular and outer longitudinal muscles) Atlas of Anatomy, 1st edition (Thieme)) Duodenum: Histology Prominent mucosal villi (V) ‒ More than jejunum or ileum Brunner’s glands (B) ‒ Submucosa layer ‒ Ducts pass through muscularis mucosae ‒ Glands secrete alkaline mucus Muscular externa ‒ Circular muscle (CM) ‒ Longitudinal muscle (LM) Wheater’s Functional Histology, 6th edition Small Intestine Jejunum and Ileum Atlas of Anatomy, 1st edition (Thieme) Simple columnar epithelium Jejunum ‒ Long villi ‒ Prominent circular folds Ileum ‒ Short villi ‒ Less prominent folds Peyer’s patches (GALT) ‒ Most common in ileum ‒ Similar in many ways to lymph nodes  Wheater’s Functional Histology, 6th edition Ileocaecal Junction Thickened muscular externa (M) Transition from villiform (S) to glandular (L) + Peyer’s patches (Ly) Ileocecal valve Muscular orifice Seals ileum from reflux Atlas of Anatomy, 1st edition (Thieme) Large Intestine Length – 5 feet Diameter (6 cm) Sections ‒ Cecum (dead-end pouch containing the appendix) ‒ Ascending colon (1 foot) ‒ Transverse colon(1.5 feet) ‒ Descending colon (0.5 feet) ‒ Sigmoid colon (1.3 feet) ‒ Rectum (0.4 feet) ‒ Anus (0.16 feet)  Atlas of Anatomy, 1st edition (Thieme) Large Intestine Flexures Hepatic (or right colic) Splenic (or left colic) Haustra (segments) Taeniae Coli Three longitudinal ribbons of smooth muscle Movements Segmental (within haustra) Antiperistaltic (reverse movements) Mass movement (stripping evacuation)  Wheater’s Functional Histology, 6th edition Rectum and Anus Rectum Short dilated terminal portion of the large intestine Columnar epithelium Anus Abrupt transition from simple columnar to SSNK epithelium Anal sphincter ‒ Internal: Smooth muscle ‒ External: Skeletal muscle Atlas of Anatomy, 1st edition (Thieme) Inflammatory Bowel Disease Immune-associated inflammation of the GI tract ‒ Crohn’s disease ▪ Mostly associated with the small intestine ‒ Ulcerative colitis ▪ Mostly associated with the large intestine Unknown etiology ‒ Genetics with environmental triggers ‒ Does not appear to be related to diet http://hopkins-gi.nts.jhu.edu/ Secondarily affects the eyes (uveitis) and kidneys Differs from Irritable Bowel Syndrome (IBS)  Celiac Disease Gluten-sensitive enteropathy Immunologic response to gluten (wheat, rye, oats, barley) Abnormal mucosal membrane (loss of villi in small intestine) Autoimmune etiology Biopsy and resolution with avoidance of gluten- Normal villi Abnormal villi containing foods makes the diagnosis. http://www.nature.com/nri/journal/v2/n9/fig_tab/nri885_F1.html Exercises What are the anatomical limits of the abdomen? What structures pass through the diaphragm to the abdomen and how and where do they pass? What are the visceral organs of the abdomen and where are they located? What is the transverse structural organization common throughout the length of the GI tract (think histology) where does it depart from the usual pattern? What organs are intraperitoneal and retroperitoneal? What are the three major arteries supplying blood to the GI tract? Exercises What is the organizational layout of venous drainage for the GI tract? What common structure must all GI blood pass through before returning to cardiac circulation and for what purpose? Describe ANS innervation of the abdomen and its regional organization Describe the source of neurological plexuses related to GI motility and secretion What are the ganglia of the prevertebral autonomic plexus and what structures are they associated with? Exercises What is the source of sympathetic and parasympathetic innervation in the abdomen? How is motility and secretion controlled in the gut? What structural features facilitate the primary function for each segment of the GI tract (e.g. transport, mixing, secretion, absorption, etc.)? What structural and or histological features distinguish each segment of the GI tract (e.g. how does the GI mucosa differ by region)? What is GALT and what is its role in immunological surveillance? Exercises To what system does the spleen belong? What is the function of this organ and what structural features enable this function? Describe the two main histological types of glandular pancreatic tissue and the functions associated with each. What is the organization of the portal triad and how does this relate to the location and flow through hepatic venules? What determines the functional and surgical subunits of the liver?