Principles of Viscera Flashcards
Two types of viscera
Solid, hollow
Layers of hollow viscera 1) 2) 3) 4)
1) Serosa
2) Muscularis
3) Muscosa
4) Lumen
Common sites of hollow lumen constriciton
Beginning, end of viscus.
Can be site specific.
Example of site-specific contraction of hollow lumen
Where male urethra pierces pelvic floor
What does a duct often do as it approaches the wall of a hollow viscus?
Narrows (an orifice)
Name of stone that can get caught in an orifice
Calculus
Arrangement of muscle in muscularis
Alternating layers of circular and longitudinal muscle
Divisions of solid viscera
Outer cortex, inner medulla
Two types of sphincters
Anatomical, functional
Anatomical sphincter
Localised muscle thickening around the wall of a tubular viscus.
Usually under tension
normal state of anatomical sphincter
Under tension
Common location of anatomical sphincters
At distal end of ducts, near an external orifice
Functional spincter
No localised muscle thickening, orifice narrowed through another mechanism
Example of functional sphincter
Bladder
Ureter enters bladder at an oblique angle. When bladder fills, pushes ureters outwards, prevents reflux.
Involuntary sphincter
Smooth muscle
Autonomic innervation
1st line of defence
Voluntary sphincter
Skeletal muscle
Somatic innervation
2nd line of defence
Example of involuntary and voluntary sphincters
In anal sphincters
Superior sphincter is involuntary, inferior sphincter is voluntary
Serous membrane
Membrane that covers all or part of a viscus
Lines the body cavity
Divisions of serous membrane
Parietal
Visceral
Nerve and blood supply of visceral serous membrane
Autonomic nerves
Same blood supply as covered organ
Nerve and blood supply of parietal serous membrane
Somatic innervation
Blood supply from abdominal wall
Location of peritoneal cavity
Below diaphragm
Retroperitoneal
Outside peritoneum
Fixed position
Intraperitoneal
Within periotoneal cavity
Attached to mesentary
Movable position
Viscera in danger of torsion
Viscera hanging from the end of a mesentary
Pattern of referred pain of a heart attack
Felt in skin above heart, under arm
Spinal cord segment supplying skin under arm
T1
Spinal cord segments supplying heart
T1 - T5
Spinal cord segments supplying skin above heart
T2 - T5
Location of pain felt from paired viscera
In skin above infected viscus
Location of pain felt from unpaired organs
Pain referred to where organ originated in midline (from where it migrated from).
Pain only felt in skin when somatic nerves are involved
Reason for unpaired viscera referred pain felt in midline
Developmental.
Unpaired viscera originate in the midline, and migrate outwards.
Pain felt from inflamed appendix
Initial pain is felt in midline
Pain shifts to left when parietal peritoneal becomes inflamed (has a somatic nerve supply)
