Abdomen Flashcards
Abdominal viscera
include:
* GI system: caudal end of esophagus, stomach, small & large intestines, liver, pancreas & gall gladder
* spleen
* kidneys & ureters
* suprarenal glands
* major vascular structures
3 main functions of adominal wall
protection
* houses & protects major viscera
* much of liver, gallbladder, stomach, spleen & parts of the colon are under the diaphragm domes–protected by thoracic wall
* supported & protected by muscular wall of the abdomen
breathing
* relaxation of abdominal muscles & contraction of diaphragm during inspiration–accomodates the expansion of thoracic cavity
* contraction of abdominal muscles & relaxation of diaphragm during expiration–assisting the elevation of diaphragm domes
changes in intraabdominal pressure
* contraction of abdominal wall (expiration) increases intraadominal pressure which promote child birth and defecation
Components
- wall
- abdominal cavity
- inferior thoracic aperture
- diaphragm
- pelvic inlet
Wall (bony and muscular wall)
“bony wall” skeletal elements
* 5 lumbar vertebrae & their IV discs (false pelvis)
* superior expanded parts of the pelvic bones (flase pelvis)
* bony compartments of inferior thoracic wall: costal margins, rib 12, end of rib 11, xiphoid process
“muscular wall”
* reinforcing the posterior aspect of wall: QL, psoas major, iliacus muscles
* reinforcing the lateral aspect of wall: transverse adnominals, internal onlique, external oblique
* reinforcing the anterior aspect of the wall: rectus adominus
Abdominal cavity general organization
A central tube (GI system) is suspended from the posterior abdominal wall & partially from the mesentery (its an organ!) in the anterior abdominal wall
* a ventral mesentery for proximal regions of the gut tube
* a dorsal mesentery along the entire length of the system
* different parts of these 2 mesenteries are named according to the organs they suspend
Adominal cavity lined by…
Peritoneum-epithelial like single layer of cells
* parietal peritoneum: lines the abdominal wall
* visceral peritoneum: covers suspended organs
Adominal viscera are either intraperioneal or retroperitoneal:
* intraperitoneal: structures suspended from the abdominal wall by the mesentary–elements of the GI system
* retroperitoneal: structures not suspended in the abdominal wall by the mesentary that lie between the parietal peritonium & abdominal wall–kidneys & ureters
During development, some organs like small & large intestines, are suspended initially in abdominal cavity by mesentary (intraperitoneal) & later become retroperitoneal secondarily by fusing to abdominal wall.
Diaphragm
Separated the abdomen from the thorax
* it attaches to the margin of the inferior thoracic aperture
* on each side, a muscular extension (crus) anchors the diaphragm to the anterolateral surface of the vertebral column:
-Right crus: vertebra L3 on R side (stronger esophagus enters in the hole holding it together)
-Left crus: vertebra L2 on L side
* posteriorly the diaphragm is anchored to arch-shaped ligaments (arcuate)
-median arcuate lig crosses the aorta & is continuous with the crus on each side
-medial & lateral arcuate ligs cross muscles of the posterior abdominal wall & attach to the transverse processes of L1 & rib 12
Pelvis
- the pelvic inlet opens directly into the abdomen & structures pass between the abdomen & pelvis through it
- the peritoneum lining the abdominal cavity is continuous with the peritoneum in the pelvis. The abdominal cavity is entirely continuous with the pelvic cavity
- the bladder expands superiorly from the pelvic cavity into the abdominal cavity
- during pregnanacy, the uterus expands freely superiorly out of the pelvic cavity into the abdominal cavity
- infections in one region can therefore spread into the other
Abdomen communication to lower limbs
The abdomen communicates directly with the thigh through an aperture formed anteriorly between the inferior margin of the abdominal wall marked by the inguinal ligament & the pelvic bone.
Structures passing through this aperture:
* major artery & vein through aperture: external iliac artery-changes to femoral artery and external iliac vein-changes to femoral vein
* femoral nerve
* lymphatics
* distal end of psoas major & iliacus muscles
Four quadrant pattern
- transumbilical plane- umbilicus & intervertebral disc ( L3 & L4)
- Vertical plane-xiphoid process & pubic symphysis
- right upper quad, left supper quad, right lower qud, left lower quad
Nine region organizational pattern
Based on 2 horizontal & 2 vertical planes
* subcostal plane-inferior to the costal margins
* transtubercular plane-tubercles of iliac crests
* vertical planes-middle clavicles to a point between ASIS & pubic symphysis
* R hypochondrium, epigastric region, L hypochondrium
* R flank, umbilical region, L flank
* R groin, pubic region, L groin
