Lower Abdomen Flashcards
1
Q
Describe a Meckel’s (ileal) diverticulum
A
- remnant of embryonic yolk stalk
- appears as a finger like pouch
- located ~1 m proximal to ileocecal valve
- May become inflamed & mimic appendicitis
2
Q
Describe the vermiform appendix.
A
- Opens into cecum inferior to ileocecal orifice
- triangular mesentary = mesoappendix
- Commonly retrocecal, but varies considerably
- Appendicitis & Appendectomy
3
Q
Describe the progression of pain associated with the progression of appendicitis.
A
- Vague pain begins in the periumbilical region
- from afferent pain referred to T10 level
- Severe pain later from R. lower quadrant
- from irritation of peritoneum of posterior abdominal wall
- Pain most severe over spinoumbilical point between the ASIS & umbilicus
4
Q
Describe the arterial supply of the lower abdomen.
A
- Celiac Trunk
- Superior Mesenteric A
- Inferior Mesenteric A
- Pancreatic A
- Renal Aa.
- Gonadal Aa.
5
Q
Describe common variations of the arterial supply of the lower abdomen
A
- Variations of SMA & IMA
- Pattern of SMA & IMA branching is variable
- Anastomoses exist between colic branches for collateral circulation
- These form a consistent vascular arc around colon via marginal a. of Drummond
6
Q
Describe the venous drainage of the abdomen
A
- Inferior Vena Cava
- Portal Vein
7
Q
Explain the difference between the portal system of veins and the caval system of veins
A
Portal system
- has no valves
- directs blood from the GI tract to the liver
- low pressure system caval system
Caval system
- IVC returns blood to heart from lower limbs, pelvis and abdomen
- valves
8
Q
Describe the portal-caval anastomoses
A
4 anastomoses: portal & caval vv
- gastric vv & esophageal vv
- paraumbilical vv & epigastric vv
- superior rectal vv & middle/inferior rectal vv
- colic vv & retroperitoneal vv
9
Q
Compare and contrast the sympathetic and parasympathetic innervation of the abdomen
A
parasympathetics
- synapse within effector organs
sympathetics
- synapse in collateral ganglia
- post ganglionic fibers leave to reach effector organs
10
Q
Describe the various autonomic ganglia and plexuses of the abdomen
A
4 major autonomic ganglia and plexuses
- Celiac ganglion
- plexus travels with celiac brs.
- Superior mesenteric ganglion
- plexus travels with SMA brs.
- Aorticorenal ganglion
- plexus travels with renal brs.
- Inferior mesenteric ganglion
- plexus travels with IMA brs.
1st 3 receive thoracic splanchnic nn & CN X brs 4th receives lumbar splanchnic nn & S2-S4 brs
11
Q
Radiographic Anatomy, Abdomen #7
A
(Stomach & Duodenum)
12
Q
Radiographic Anatomy, Abdomen #10
A
(Colon, Large intestine)
13
Q
Radiographic Anatomy, Abdomen #20
A
(Superior Mesenteric Artery)
14
Q
Radiographic Anatomy, Abdomen #21
A
(Inferior Mesenteric Artery)
15
Q
Describe the stomach
A
- Cardiac orifice
- entrance from esophagus
- Pyloric sphincter
- exit to duodenum
- Lined with Rugae
- temporary folds within the body of the stomach
16
Q
Describe the small intestine
A
- Duodenum
- fixed & relatively immobile
- Jejunum & ileum
- tethered, but very mobile
- combined length of 3 segments~20 ft.
- Plicae Circularis
- permanent folds within intestine
- become more diffuse distally
- Ileum empties into cecum at ileocecal junction
17
Q
Describe how vasa recta and arterial arcades help distinguish parts of the intestine
A
- in the small intestine
- help differentiate ileum and jejenum
- ileum
- vasa recta are long and arterial arcades are short and less branched
- jejenum
- vasa recta are shorter and arterial aracades are larger and more branched
18
Q
Describe the large intestine
A
- aka colon
- 5 segments & 2 flexures
- Terminates into Rectum
- ‘Frames’ small intestines
- Segments
- Cecum
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
- Flexures
- R. colic (hepatic)
- L. colic (splenic)
19
Q
Describe the colon and it’s specializations
A
- frames the intestines
- Teniae coli
- 3 smooth m. bands paralleling length of colon
- Haustra coli
- outpouchings produced by teniae coli
- Epiploic appendages
- fat tags found along the colon
20
Q
Describe the Celiac Trunk
A
- 1st major br. of Abdominal aorta
- Supplies liver, gallbladder, esophagus, stomach, pancreas & spleen
- 3 main branches
- Common hepatic a
- L. gastric a
- Splenic a
21
Q
Describe the Superior Mesenteric A.
A
- 2nd major branch of abdominal aorta
- ~1 cm inferior of celiac
- sends 15-18 intestinal aa to small intestine
- supplies up to proximal 2/3 of transverse colon
- via ileocolic, R. colic & middle colic
22
Q
Describe the Inferior Mesenteric A.
A
- 3rd major branch of abdominal aorta
- ~5 cm superior to aortic bifurcation
- supplies colon from distal 1/3 of transverse colon
- via L. colic, sigmoid (4) & superior rectal
23
Q
Describe the Pancreatic Arteries and where they anastomose
A
- Gastroduodenal a. gives off Superior pancreaticoduodenal aa.
- SMA gives off Inferior pancreaticoduodenal aa.
- Anastomose and supply head of pancreas & duodenum
- Splenic a. supplies rest of pancreas with additional branches
24
Q
Describe the Renal Aa
A
- lateral branches of abdominal aorta (lateral to SMA)
- Enter hilum of each kidney to supply it
- sends off brs. to adrenal glands and ureters
- other adrenal branches from inferior phrenic aa & aorta
25
Describe the Gonadal Aa
* lateral branches of abdominal aorta (inf. to renal aa.)
* Ovarian aa (♀)
* crosses over ureters & iliac vessels
* descends to pelvis to supply ovaries
* Testicular aa. (♂)
* crosses over ureters & enters inguinal canal
* descends into scrotum to supply testes
26
Describe the Inferior Vena Cava
* largest vein in body
* begins at ~L5 level
* at union of common iliac vv.
* returns poorly oxygenated blood from LL, most of the back, abdominal wall, & abdominopelvic viscera to the RA of heart
* Blood from viscera
* via Portal venous system
27
Describe the Portal Vein
* Formed by union of splenic and superior mesenteric vv. (L2)
* Venous return from
* Spleen
* Pancreas
* Gall bladder
* Abdominal gastrointestinal tract
* Returns nutrient rich, poorly oxygenated blood to the liver
* Then via IVC to the RA of heart
28
Describe the clinical significance of the portal-caval anastomoses
* Portal venous system has no valves
* reversal of blood flow into caval vv is possible
* portal hypertension restricts blood flow
* causes caval vv to become engorged
* may them become dilated & varicose
29
Describe the clinical significance of Portal-Caval Anastomoses and dilated Caval Veins
* Dilated espophageal vv
* produce esophageal varices
* Dilated epigastric vv.
* produce caput medusae
* Dilated infr. & mid. rectal vv
* produce hemorrhoids
Note: These can lead to vascular rupture & severe hemorrhaging.
Caput medusae- distended and engorged paraumbilical vv. Often resulting from cirrhosis
30
Describe the nerve supply of the abdomen
* Innervation to viscera is via autonomic n. plexuses
* Sympathetic fibers
* originate from T5-L2(3) thoracolumbar
* Parasympathetic fibers
* originate from CN X & S2-4 craniosacral
31
Describe the sympathetics of the abdomen
* Preganglionic splanchnic nn
* synapse in collateral ganglia
* Postganglionic fibers
* leave ganglia to reach effector organs
* post-synaptic fibers travel on all main arterial branches
* celiac trunk, SMA, renal aa, IMA and all their branches
32
Describe the parasympathetics of the abdomen
* Preganglionic nerves from CN X travel on upper arterial branches
* celiac trunk, SMA, renal aa, and all their branches
* Preganglionic nerves from S2-S4
* travel on lower arterial branches IMA and branches
* Synapses occur within effector organs
