Abdominal Composition and Vasculature Flashcards
Peritoneal cavity
Made up of ligaments and folds that connect organs to each other and abdominal walls
Peritoneal cavity is comprised of
- Lesser and greater omentum
- mesenteries
- ligaments
- fluid spaces
What is peritoneum
Smooth membrane that lines the entire abdominal cavity and the organs contained within the cavity
Parietal peritoneum
Lines the walls of the cavity
Visceral peritoneum
Lines the abdominal organs
Greater sac
General peritoneal cavity
Lesser sac
Smaller area or peritoneal cavity formed by spleen and posterior stomach
Greater and lesser sac communicate through
Opening inferior to liver and duodenum called epiploic foramen
Lesser omentum
Double layer of peritoneum extending from the liver to the lesser curvature of the stomach
The lesser omentum does what for the stomach
Acts like a sling
Greater omentum
Apron-like fold of peritoneum that hangs from the greater curvature of the stomach
The greater omentum lies
Freely over intestines except for the superior portion which is fused with the transverse colon
The greater omentum can be compared to
A skirt for the intestines, covers small intestines
The lesser omentum attaches
Stomach to liver
Mesentery
2 layered peritoneal folds which suspend the small bowel and colon to the posterior abdominal and pelvic wall
Mesentery is best visualized on ultrasounds with
Presence of ascites
Peritoneal spaces
- right and left subphrenic spaces
- posterior cul-de-sac
- subhepatic space
- lesser sac
- right and left paracolic gutters
Anterior abdominal wall layers (superficial to deep)
- skin
- fascia
- muscle
- fascia transversalis
- peritoneum
Camper’s fascia
Fatty superficial layer
Scarpa’s fascia
Deep fibrous layer
Anterior abdominal wall muscles
- rectus abdominus
- external oblique
- internal oblique
- transverse abdominal
Rectus abdominus
Longitudinally oriented muscles extending from xiphoid process to pubic bone, midline
Rectus abdominus muscles are encased in
A sheath which joins at the midline to form the linea alba, sheath attaches and secures musculature to abdominal cavity
Sonographic evaluation of anterior abdominal wall
Fatty composition layers: Hypoechoic depending on content
Musculature: linear striations, Hyperechoic (high density structures)
Aorta
Main vessel that carries blood from heart to rest of body
Abdominal aorta
Portion of descending aorta that supplies blood to abdomen, pelvis, and lower extremities
Aorta layers
- Tunica intima (inner)
- Tunica media (mid)
- Tunica adventitia (outer)
Aorta position
Posterior to:
- left lobe
- body of pancreas
- pylorus of stomach
- splenic vein
Main branches of aorta
- celiac
- SMA
- renal arteries
- IMA
Celiac branch
First branch off aorta
Sub-branches: left gastric artery, common hepatic artery, splenic artery
Supplies stomach, liver, spleen
Superior Mesenteric artery supplies
Duodenum, small intestines, and transverse colon
Renal arteries
Left renal artery branches off aorta first
Inferior mesenteric artery supplies
Large intestines
Aorta bifurcates at
Level of L4
Aorta bifurcates into
Right and left iliac arteries which supply respective legs
Sonographic evaluation of aorta
- blood filled lumen: anechoic
- walls: echogenic
- long, pulsatile, tubular structure
- located anterior and left of the spine
- can use left lobe of liver as landmark
Sagittal aorta protocol
Proximal: AP diameter above celiac branch
Mid
Distal: normal increase in diameter due to upcoming bifurcation
Bifurcation: right and left common iliac arteries
Transverse aorta protocol
Proximal
Mid
Distal
Bifurcation: color eval
Patient prep
NPO 6-8 hours
Curved transducer 3-5 MHz
Patient scanned supine, can use decub to move gas
Normal proximal AP diameter of aorta
Men: 2.5-2.7 cm
Women: 2.1-2.3 cm
Thrombus
Accumulation of blood cells, can embolize resulting in life threatening blockage of vessel
Calcification
Accumulation of plaque products along the walls of the artery, resulting from disease, old age, poor dietary habits
Wall dissection
Inner layer of aortic wall tears, caused inner and middle layer to separate
What are we looking for during aorta evaluation
- normal diameter
- thrombus
- calcification
- wall dissection
Inferior vena cava
Main vessel that carries blood from the extremities and abdominal/pelvic cavity back to the heart
IVC is formed by
Union of the common iliac veins
The IVC ascends
Vertically through the retroperitoneal space, travels posterior to the liver and right of the aorta
Sonographic evaluation of IVC
- blood filled lumen: anechoic
- walls: thin, collapsible, not as echogenic as aorta walls
- phasic: diameter changes, color doppler evaluation
IVC protocol
Typically using IVC as landmark reference
Included in abdominal evaluation
Sagittal: proximal with color Doppler
Look for thrombus
