GIS01 General anatomy of the abdomen Flashcards
Trunk
3 parts:
- Thorax
- Abdomen
- Pelvis
Abdomen
3 parts:
1. Abdominal viscera
within 2. Abdominal cavity
surrounded by 3. Abdominal wall
Functions of abdominal cavity
- Houses and protects major viscera
- Involvement in breathing
- -> relaxation of abdominal muscles during inspiration
- -> contraction of abdominal muscles during expiration - Changes in the intra-abdominal pressure
- -> Micturition
- -> Defecation
- -> Child birth
Abdominal viscera
3 layers (Anteroposterior)
Anterior:
1. Stomach
2. Transverse colon
Middle:
- Spleen
- Pancreas
- Gallbladder
- Duodenum
- Ascending colon with cecum and vermiform appendix
- Descending colon
Posterior:
- Kidneys
- Adrenal glands
- Ureters
- Bladder
- Abdominal aorta
General organisation of abdominal cavity
Upper border: Diaphragm
Side border: Abdominal muscle
Lower border: Pelvic inlet
Overlap with upper Thoracic cavity
Superior part of the abdominopelvic cavity is continuous with the pelvic cavity
Abdominal viscera either:
- Suspended in the peritoneal cavity (intraperitoneal organs)
- Positioned between peritoneal cavity and wall (e.g. retroperitoneal kidneys)
Abdominal cavity: Body cavity
Peritoneal cavity: Serous cavity
Peritoneal cavity
Between the visceral and parietal peritoneum is the peritoneal cavity
- -> potential space
- -> filled with peritoneal fluid (50mL)
- -> lubricates organs to allow movements
2 parts:
- Greater sac
- Lesser sac (omental bursa) (behind Stomach and Liver)
- -> connection: Omental foramen = Epiploic foramen = foramen of Winslow
Greater omentum: from Greater curvature of stomach to Transverse colon
Lesser omentum: from Lesser curvature of stomach to Liver
- lead to Portal Hepatis
—> Hepatic Artery proper
—> Hepatic Portal vein
—> Common Hepatic duct
Peritoneum
- Thin, continuous serous (mesothelial) membrane
- Sensitive
- Semi-permeable
Functions:
- Lines wall of abdominopelvic cavity (Parietal peritoneum)
- Covers viscera (Visceral peritoneum)
- Peritoneal formations (mesenteries, omenta, ligaments)
Peritoneal formations
- Connections between visceral and parietal peritoneum
- Convey neurovascular structures and ducts to and from viscera
Mesenteries
- attach viscera to abdominal wall
- ***Foregut: ventral + dorsal mesentery
- ***Midgut + Hindgut: ONLY dorsal mesentery
- e.g. mesentery of small intestine; transverse mesocolon / sigmoid mesocolon
Omenta
- 2 layers of peritoneum
- Greater omentum, Lesser omentum
Ligaments
- connect 2 organs / attach an organ to body wall
- e.g. splenorenal ligament, gastrophrenic ligament
***Intra- and Retroperitoneal structures
Intraperitoneal organs:
- Organs completely covered by peritoneum and suspended by mesentery
- Abdominal peritoneal cavity: **Stomach, Spleen, Liver, Gallbladder, Small intestine (some), **Transverse colon, Sigmoid colon, Cecum
- Pelvic peritoneal cavity: ***Uterus, Ovaries, uterine tubes, superior rectum
- can only be reached once the abdominal cavity is opened and this increases the risk of infection and complications
Extraperitoneal organs:
- Organs without mesentery, neurovascular structures located in extraperitoneal CT
- Primarily extraperitoneal
- -> behind abdominal / pelvic peritoneal cavity: ***Kidneys, Adrenal glands, ureters
- -> below pelvic peritoneal cavity / infraperitoneal: ***Urinary bladder, Prostate, Vagina, rectum past sacral flexure
- Secondarily extraperitoneal (become extraperitoneal during embryonic development; organs covered by peritoneum anteriorly)
- -> behind abdominal / pelvic peritoneal cavities: **Duodenum, **Pancreas, ***Ascending / Descending colons, rectum up to sacral flexure
簡單而言: Stomach (Intra) —> Duodenum (1st part: Intra) —> Duodenum (rest: Extra) —> Jejunum (Intra) —> Ileum (Intra) —> Caecum (Intra) —> Ascending colon (Extra) —> Transverse colon (Intra) —> Descending colon (Extra) —> Sigmoid (Intra) —> Rectum (Extra)
Abdominal wall bony framework
- 5 Lumbar vertebrae
- Superior bony pelvis
- Bones of inferior aspect of thorax
Abdominal wall muscles
- Quadratus lumborum
- Psoas major
- Iliacus
- Transversus abdominis (最入)
- Internal oblique (Pocket orientation, Continuous with Rectus abdominis) (Internal oblique係側面, Rectus abdominis係中間)
- External oblique (最出, Surgical hand orientation)
- Rectus abdominis
- Pyramidalis
- -> Structural continuity provided by aponeuroses and fasciae
- -> covered by skin
Surface anatomy
- some structures can be palpated through skin
- some palpable features help visualize deeper structures
4 Quadrants:
- Right Upper
- Left Upper
- Right Lower
- Left Lower
- divided by **Transumbilical plane + **Median plane (Mid-sagittal plane)
9 Regions:
- Right hypochondrium
- Epigastric
- Left hypochondrium
- Right flank
- Umbilical
- Left flank
- Right groin
- Pubic
- Left groin
- divided by **Midclavicular planes x2, **Subcostal plane, ***Intertubercular plane
Vertebral level L1
Transpyloric plane (important landmark):
- go through lower level of ***L1
- midlevel between jugular notch (just above manubrium) and pubic symphysis
- crosses costal margin at ***9th costal cartilage
Significance:
- opening of Stomach into Duodenum
- crosses Body of Pancreas
- approximate position of Kidney hila
***Mesenteries
Foregut and associated organs: Ventral + Doral mesenteries
Midgut and Hindgut: only Dorsal mesenteries
