Lab 10: Abdomen Flashcards
abdominal skeleton
- bounded superiorly by the abdominal diaphragm and inferiorly by the upper margin of the bony pelvis
- consists of a large cavity that is walled by muscle and serous membrane
- abdominal cavity is continuous inferiorly with the pelvic cavity which is enveloped by the bony pelvis
- structure of rib cage and tilt of pelvis cause the thoracopelvic gap between them to be higher in front than behind
- dome of abdominal diaphragm is very high -> from margins of 12th ribs up to the level of 5th ribs
- some abdominal organs are covered by the lower 5 or 6 ribs and their costal cartilage
relationship of abdominal viscera to the rib cage
- several ab organs are partially, largely, or entirely covered by the rib cage
- liver- deep to rib cage, covered anteriorly by the bottom of the sternum and some of the inferior costal cartilage to the left, on the right -> covered by the 5th to 11th ribs and their costal cartilage, posteriorly it is deep to the 9th to 11th ribs
- stomach- covered anteriorly on the left side by the 5th to 8th ribs
- spleen- entirely covered by the 9th to 11th ribs
- kidneys- deep to ribs -> both adrenal (suprarenal) glands are covered by the 12th ribs
roof of the abdominal cavity
- abdominal diaphragm forms the roof of the abdominal cavity
- innervated by phrenic nerve (C3-C5)
anterolateral walls of the abdominal cavity
- cover by 4 muscles on each side
- one is strap-like longitudinal muscles in the front and 3 sheet-like muscles more laterally
anterior abdomen muscle: rectus abdominis
- rectus abdominis- strap-like muscle that arises from the xiphoid (and 5th to 7th costal cartilage)
- runs from superior (xiphoid process), 5th-7th costal cartilages -> to the pubis
- 2 sheets
- inserts on the superior edge of the pubis
- flexes the trunk
- in between each muscle belly there is a tendinous intersections muscle section
- 3 (sometimes 4) connective tissue tendinous intersections that interrupts the muscle belly
- recuts sheath- encloses the rectus abdominis
- formed by aponeuroses of 3 lateral wall muscles
- arcuate line (bellow belly bottom)- below this line the rectus sheath is only in the front (not behind)
- semilunar line- where it stops
- tendinous sheath of lateral wall muscle - make up the layers of rectus abdominis
- innervated by spinal nerves T7-T12
3 layers of rectus abdominis
external oblique aponeuroses
- internal oblique aponeuroses
- transversus abdominis
anterolateral wall: external oblique
- external oblique- most superficial layer
- arises from the lower 8 ribs and the iliac crest
- fibers run inferiorly and medially and become tendinous anteriorly to form the linea alba
- inguinal ligament
- thick inferior edge of aponeurosis -> stretches between the anterior superior iliac spine and the pubic tubercle -> inguinal ligament
- superficial inguinal ring- hole in the aponeurosis above the pubic tubercle (testes exit here)
- inguinal canal passes though the inguinal ligament- testes originate here and drop)
anterolateral wall: internal oblique
- middle layer
- arises from the front of the iliac crest and the inguinal ligament
- fibers run superiorly and medially -> insert onto ribs 10-12
- inferior edge form an arc above the inguinal ligament that is deep to and slightly lateral to the superficial inguinal ring
- above the umbilicus -> aponeurosis splits into superficial and deep layers around rectus abdominis
- below umbilicus -> aponeurosis runs superficial to rectus abdominis to mesh with the linea alba
- runs the opposite direction of external oblique
anterolateral wall: transversus abdominis
- running horizontally
- deepest muscle layer
- arises posteriorly form an aponeurosis that passes behind quadratus lumborum
- attaches to transverse processes of L1-L5
- also attaches to the lower 6 costal cartilages -> iliac crest and inguinal ligament
- fibers run anteriorly to become aponeurotic and mesh with the linea alba
- above the umbilicus -> aponeurosis passes behind rectus abdominis
- below umbilicus -> its aponeurosis passes in front of rectus abdominis
transversalis fascia
- fascial layer
- below the three layers of muscle in the anterolateral wall
- internal aspect of the abdominal wall is lined with a layer of tissue known as the transversalis fascia
rectus sheath
- formed from the aponeuroses of the obliques and transversus abdominis
- arcuate line- inferior margin of posterior rectus sheath
- below arcuate line -> the rectus abdominis sits directly on transversalis fascia
- weak spot in abdominal wall
- aponeuroses of the left and right external oblique muscles cover the rectus abdominis muscles anteriorly and fuse to the midline to form the linea alba
above arcuate line: superficial to deep
- external oblique aponeurosis
- first half of internal oblique aponeurosis
- rectus abdominis
- second half of internal oblique
- transversus abdominis
- transversalis fascia
- parietal peritoneum
- first and second half enclose
below arcuate line: superficial to deep
- external oblique aponeurosis
- internal oblique aponeurosis
- transversus abdominis
- rectus abdominis
- transversalis fascia
- parietal peritoneum
pyramidalis
- arises from the pubis and inserts into the linea alba
- 80% of people have this small muscle
linea alba
- left and right muscles (anterior abdomen muscle) are separated by a longitudinal band of connective tissue called the linea alba
- tendinous intersections and linea alba create the six pack
- aponeuroses of the left and right external oblique muscles cover the rectus abdominis muscles anteriorly and fuse to the midline to form the linea alba
posterior wall of abdomen: quadratus lumborum
- forms most posterior wall
- laterally flexes trunk
- forms the bulk of the posterior abdominal wall
- originates on the iliolumbar ligament and iliac crest
- inserts onto the transverse process of L1-L4 and the lowermost rib
posterior wall of abdomen: psoas major
- originates on vertebral column from T12-L5
- runs down to iliacus and merges -> forms iliopsoas m.
- hip flexor, laterally flexes trunk
- forms the medial part of the posterior abdominal wall adjacent to the vertebral column
- arises from the bodies and intervertebral discs of T12-L5
- fibers merge with those of iliacus to form a conjoint iliopsoas tendon that inserts onto the lesser trochanter of the femur
posterior wall of abdomen: psoas minor
- only present in 50-60% of people
- runs along the front of psoas major
- very small
- arises from the bodies and disc of T12-L1 and runs along the front of psoas major
- inserts onto the iliopubic eminence of the pelvis
posterior wall of abdomen: abdominal diaphragm
- forms the superoposterior wall of the abdominal cavity
- where all the posterior abdominal wall muscles end
peritoneum
- serious membrane, like pleura and pericardium
- parietal peritoneum- outer layer
- visceral peritoneum- inner layer, lies against walls of organs
- retroperitoneal organs- not enclosed by peritoneal cavity
- mesentery- reflected peritoneum that folds around an organ
- greater omentum- fat flap, double layer of visceral peritoneum (specialized mesentery)
retroperitoneal organs
- suprarenal glands
- aorta/inferior vena cava
- duodenum (2nd and 3rd parts)
- pancreas
- ureter
- colon (ascending and descending)
- kidneys
- esophagus
- rectum
- SAD PUCKER
mesenteries
- small intestine is suspended by the mesentery (proper)
- transverse colon suspended by the transverse mesocolon
- omentum- lesser and greater
- connects to transverse colon and hangs of the greater portion of stomach -> greater omentum
digestive canal organs
- esophagus
- stomach
- small intestine
- large intestine
accessory organs
- liver
- gallbladder
- pancreas
- spleen
biliary tree
-carries bile and digestive enzymes from these organs to the small intestine
stomach
- made up of walls of muscle layers: circular, longitudinal, oblique
- mixes food with acids to make chyme
- rugae- rough ridges for mechanical digestions
- 3 parts: fundus, body, pylorus
- 2 sphincters: cardiac and pyloric
- cardiac sphincter- between esophagus and stomach (prevents regurgitation of acid)
- pyloric sphincter- between stomach and duodenum
stomach
- made up of walls of muscle layers: circular, longitudinal, oblique
- mixes food with acids to make chyme
- rugae- rough ridges for mechanical digestions
- 3 parts: fundus, body, pylorus
- 2 sphincters: cardiac and pyloric
- cardiac sphincter- between esophagus and stomach (prevents regurgitation of acid)
- pyloric sphincter- between stomach and duodenum (discharge chyme)
stomach: mesenteries
- intraperitoneal
- attached to posterior
- lesser omentum- connects stomach and liver, runs in lesser curvature
- greater omentum- hangs down from the stomach, connects with transverse colon -> runs along greater curvature
small intestine
- responsible for digesting food and absorbing nutrients
- 3 regions: duodenum (mainly retroperitoneal), jejunum (freely mobile, suspended by mesentery), ileum (suspended by mesentery)
- ileum opens into the cecum of the large intestine
duodenum
- most proximal part of small intestine
- c-shaped
- curves around head of pancreas
- pierced by: main pancreatic duct + bile duct through major duodenal papilla
jejunum
- wide lumen
- thick walls
- numerous circular folds
- superior mesenteric artery supply
- few arcades, long vasa recta
- shorter
ileum
- narrower lumen
- thin walls
- fewer circular folds
- superior mesenteric artery supply
- many arcades, short vasa recta
- longer
small intestine: mesenteries
- jejunum and ileum are intraperitoneal
- attached to posterior abdominal wall by mesentery
- mesentery- surrounding the blood vessels that go to the organs
- mesentery proper
- encroaches on intestinal walls in the ileum, not in the jejunum
large intestine
- responsible for water absorption
- storing undigested material
- 8 regions:
- cecum
- vermiform appendix
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
- anal canal
haustra and taeniae coli
- differentiates large intestine
- haustra- pouches of the large intestine
- taeniae coli- longitudinal thin muscle that goes throughout the entire large intestine
- omental (epiploic) appendages- fat blobs that hang
large intestine: mesenteries
- partly intraperitoneal
- ascending and descending colon, rectum etc. are retroperitoneal
- transverse colon is intraperitoneal
- greater omentum- attaches the transverse colon to the stomach
- transverse mesocolon- attaches transverse colon to posterior abdominal wall
liver
- produces bile
- filters blood from GI trace
- produces bile
- metabolizes carbs, fats, and proteins
- lobes (4)- right lobe, left lobe, quadrate lobe (next to gallbladder!), caudate lobe (next to IVC)
- round ligament of the liver (ligamentum teres)- used to be umbilical vein
- falciform ligament- separates the right and left lobe
- falciform ligament splits into 2- top portion (posterior) of the liver is bare (no peritoneum)
- hepatic portal vein, hepatic artery proper, and common bile duct (portal triad) going into the liver -> porta hepatis
porta hepatis
- where blood vessels enter and exit the liver
- hepatic artery- carries oxygenated blood to tliver
- portal vein- drains blood from GI tract to liver
- common bile duct- drains bile from the liver (joins cystic duct from gallbladder to form common bile duct
- deoxygenated blood drains from the liver into the inferior vena cava
biliary tree
- right + left hepatic ducts -> common hepatic ducts
- cystic duct + common hepatic duct -> common bile duct
- bile ducts and the main pancreatic duct both drain into the duodenum, via the major duodenal papilla
- bile helps break down lipids
kidneys
- excrete metabolic waste
- maintain water and electrolyte balance
- blood vessels: renal arteries, renal veins
- hilum of kidneys transmit the renal artery, renal vein, and ureter
- regions: pelvis (collection chamber for urine) -> major and minor calyces; medulla (urine ducts) -> renal pyramids
- renal pyramids- receive urine form collecting ducts of the nephron
- renal papilla (opening to minor calyx)
- renal pyramids -> renal papilla -> minor calyx -> major calyx -> renal pelvis -> ureter -> bladder
adrenal glands
- endocrine glands, secrete hormones including adrenaline
- blood vessels- suprarenal arteries (3) suprarenal veins
- superior suprarenal artery branches off inferior phrenic artery (which supplies the diaphragm)
- middle suprarenal artery off aorta
- inferior suprarenal artery off renal artery
renal artery and veins relationship
- renal veins are superficial to renal arteries
- left renal vein is much longer than the right (bc it must cross over aorta)
- inferior mesenteric artery (IMA) comes off the aorta over the left renal vein
nephron: tubular component
- glomerular (bowmans) capsule
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
- collecting duct
- urine leaves through collecting duct
- things that are moved into the blood leave through efferent arteriole
nephron: vascular component
- afferent arteriole
- glomerulus
- efferent arteriole
- peritubular capillary network
arteries of abdomen
- 3 major branches of abdominal aorta:
- celiac trunk (T12-L1)- emerges near aortic hiatus -> supplies foregut
- superior mesenteric artery (L1)- supplies midgut
- inferior mesenteric artery (L3)- supplies hindgut (splenic flexure, ascending and descending colon, rectum)
- also note that paired visceral branches from the aorta: middle suprarenal arteries, renal arteries, gonadal arteries
celiac trunk
- main branches:
1. left gastric artery: supplies stomach, esophagus
2. splenic artery: supplies pancreas spleen (gives off left gastroepiploic artery)
3. common hepatic artery: splits into gastroduodenal artery and proper hepatic artery - gastroduodenal artery- supplies duodenum (gives off right gastroepiploic artery)
- proper hepatic artery- supplies liver (gives off right gastric artery to stomach and cystic artery to gallbladder)
anastomoses
- 2 different sources of blood join and form one artery
- lesser curvature gets blood from left gastric artery and right gastric artery -> they combine
- left side
superior mesenteric artery
-L1
-enters mesentery of small intestine
-supplies distal 1/3 of duodenum, remaining small intestine, proximal large intestine
1. jejunal branches
2. ileal branches
3. middle colic artery: gives blood to transverse colon and some ascending colon,
4.
inferior mesenteric artery
- supplies distal large intestine and proximal rectum
- branches:
1. left colic artery- supplies distal transverse colon and proximal descending colon
2. sigmoid branches- supply descending colon, sigmoid colon
3. superior rectal artery-
venous drainage
- systemic venous system drains blood from the whole body (except the GI tract)
- portal venous system drains blood from the GI tract
- passes through liver before continuing to the heart