Abdomen 1.2 Flashcards
What nerves innervate the viscera of the abdominal cavity?
Sympathetic and parasympathetic
Where do the sympathetic nerves come from?
coursing in the thoracic splanchnic nerves (from T5-T12 spinal cord levels) and lumbar splanchnics (upper lumbar levels)
Where do the sympathetic nerves synapse?
- synapse largely in 3 major collections of ganglia:
1. celiac
2. superior mesenteric
3. inferior mesenteric ganglia
What gives rise to the the superior hypogastric plexus?
A nerve plexus continuing from this most inferior ganglion
What does the superior hypogastric plexus provide?
Sympathetic innervation to pelvic viscera
Where does parasympathetic innervation to the upper two thirds of the abdominal viscera come from?
The vagus nerve
Where are the upper two thirds of the abdominal viscera derived from?
The foregut and midgut portions of the embryonic gut
Where do the remaining portions of the abdominal and pelvic viscera (embryonic hindgut) receive parasympathetics from?
S2, S3, S4 via pelvic splanchnic nerves
How do most of the autonomic fibres reach the viscera?
By travelling on the blood vessels originating from the celiac trunk and the superior and inferior mesenteric arteries
Where do autonomic fibres to the bowel synapse? What is this?
- on ganglion cells of the enteric nervous system
- Intrinsic plexus of ganglia (myenteric and submucosal) for fine control of bowel function
Where do preganglionic sympathetic fibers synapse?
In ganglia of the sympathetic trunk
What is the course of preganglionic sympathetic fibres?
Course via splanchnic nerves to synapse in collateral ganglia such as celiac or superior mesenteric ganglion or pass directly to the adrenal medulla
What does the parasympathetic fibers to the upper two-thirds of the abdominal viscera are conveyed by the vagus nerve do?
sends preganglionic fibers directly to the walls of the organs innervated
How do these parasympathetic fibers end?
end in terminal ganglia in the visceral wall, which give rise to short postganglionic fibers
How is pain sensation from the bowel conveyed?
afferent fibers whose nerve cell bodies reside in the spinal (dorsal root) ganglia of the T5-L2 spinal levels
What is referred pain?
visceral pain is often referred to somatic regions of the body corresponding to the dermatomes supplied by the spinal cord segment that receives the visceral afferent (sensory) input
What courses to the kidneys?
a rich plexus of sympathetic nerves arising from the superior mesenteric ganglion
Where do sympathetics to the pelvic viscera arise from?
superior hypogastric plexus formed below the inferior mesenteric ganglion
How do these nerves course?
on either side of pelvic viscera to the inferior hypogastric plexus
Where does parasympathetic fibers to the kidneys arise from?
vagus nerve
Where do the pelvic viscera and lower abdominal viscera receive their parasympathetic fibres from?
pelvic splanchnic nerves arising from S2, S3, and S4
Where is renal colic felt?
The pain (renal colic) of a renal stone that passes from the kidney and into the ureter is usually felt from the loin to the groin as the stone works its way toward the urinary bladder in the pelvis
What are the narrow points on the pathway of a renal stone?
- ureteropelvic junction
- midureter where it crosses the iliac vessels
- the ureterovesical junction
How is the pain of a renal stone conveyed?
by visceral afferents to the corresponding spinal (dorsal root) ganglia and then to the spinal cord (T11-L2); thus, the pain is localized to these dermatomes
How does pain afferents from the abdominal viscera pass to the spinal cord?
by following the thoracic and lumbar splanchnic sympathetic nerves (T5-L2)
Where are the nerve cell bodies of the afferent fibers from the viscera are located?
spinal ganglia of the respective spinal cord levels
What is most visceral pain related to?
irritation from inflammation, ischemia, distention, or compression
Which visceral pain is referred to both anterior and posterior body walls?
- stomach
- gallbladder
- spleen
- liver
What do veins of the anterior abdominal wall provide?
important superficial anastomotic network of veins that returns blood to the heart
What do the veins of the anterior abdominal wall include?
anastomoses between the superficial epigastric veins and lateral thoracic veins
Where do the superficial epigastric veins drain?
into the inguinal ligament
Where do the lateral thoracic veins drain?
axillary vein
What do the inferior epigastric veins anastomose with on a deeper plane?
the superficial epigastric veins and the internal thoracic (mammary veins)
What do anastomoses between superficial and deep veins allow?
ensure that venous blood can return to the heart via several different routes if necessary (which is important if a venous route is obstructed)
Where does the inguinal canal extend?
from the deep inguinal ring to the superficial inguinal ring
How is the spermatic cord related to the inguinal canal?
traverses this canal
Where do indirect inguinal hernias occur?
- 75% of inguinal hernias
- occur lateral to the inferior epigastric vessels
- pass through the deep inguinal ring and inguinal canal,
- are enclosed within the internal spermatic fascia of the spermatic cord
Where do direct inguinal hernias occur?
- medial to the inferior epigastric vessels (Hesselbach’s triangle)
- pass through the posterior wall of the inguinal canal
- are separate from the spermatic cord
What do branches of the celiac trunk supply?
adult derivatives of the embryonic foregut and the spleen, a mesodermal derivative
What does the celiac trunk give rise to?
- left gastric artery
- the common hepatic artery
- the splenic artery
What do the primary branches of the celiac trunk distribute arterial blood to?
- liver
- gallbladder
- portions of the pancreas
4 . spleen - stomach
- proximal duodenum
Where is pain secondary to the pathophysiologic processes common?
epigastric region
What is in the epigastric region or refer pain there or dermatomes related to T5-T9 and T10 spinal levels?
stomach, duodenum, spleen, pancreas, liver, and gallbladder
Where does the superior mesenteric artery supply blood to?
adult gastrointestinal tract derivatives of the embryonic midgut
What are the areas that the superior mesenteric artery supplies blood to?
- arteries to a portion of the pancreas
- the distal duodenum
- all of the small intestine
- the appendix
- the ascending colon
- most of the transverse colon
Which embryonic derivates does the inferior mesenteric artery supply?
embryonic hindgut derivatives
What does the inferior mesenteric artery supply?
- distal transverse colon
- descending and sigmoid colon
- superior portion of the rectum
Are there anastomotic channels between the branches of the superior and inferior mesenteric arteries?
yes
What happens if blood flow from one bowel region is compromised?
collateral flow from anastomotic branches usually can assist in supplying blood to the compromised region
