Anatomy - ANS

Question 1

Nervous System Schematic

Answer 1

Question 2

Autonomic Nervous System

Answer 2

• ANS
  
  • primarily described as an EFFERENT/MOTOR system
  • AFFERENT (Sensory) fibers travel alongside the efferent nerve fibers
    
    • carry impulses from target organs
    • similar to somatic system

Question 3

Wjat are the 3 types of Ganglia?

Answer 3

Autonomic Ganglia

• collection of nerve cells OUTSIDE CNS
• contain postganglioninc sympathetic or parasympathetic nerve cell bodies

Sympathetic Ganglia (fight or flight)

• Sympathetic chain ganglia (para vertebral ganglia)
  
  • chain ganglia found at all levels of the spinal cord/nerves
• Preaortic sympathetic ganglia (prevertebral ganglia)
  
  • ONLY located in the abdomen
  • associated w/ major branches of abdominal aorta

Parasympathetic Ganglia (rest and digest)

• discrete parasympathetic ganglia = ONLY found in the head
• FOR THE REST OF THE BODY:
  
  • postganglionic parasympathetic cell bodies are found scattered near or in the walls of target organs

Question 4

What are the Ganglion Characteristics of Autonomic Schematic (Sympathetic vs. Parasympathetic)?

Answer 4

CNS (Cell bodies)

• Sympathetic
  
  • Short = preganglion (myelinated)
  • Long = postganglion (unmyelinated)
  • Target = smooth m.; cardiac m.; glands
• Parasympathetic
  
  • Long = preganglion (myelinated)
  • Short = postganglion (unmyelinated)
  • Target = smooth m.; cardiac m.; glands
    *

Question 5

What are the subdivision of the ANS?

Answer 5

Sympathetic:

• thoracolumbar system
• T1-L2 outflow
  
  • no preganglionic fiber before T1 or after L2

Parasympathetic:

• craniosacral system
• CN, III, VII, IX, X & S2,3,4

Targets:

• smooth muscle
• glands
• cardiac muscle
• Both systems need TWO neurons to effect the targets

Question 6

What are the Autonomic Ganglia (visceral motor) connections?

Answer 6

Parasympathetic Ganglia

• 4 cranial ganglia
• rest in organ wall

Sympathetic Ganglia

• Sympathetic chain gangia
• Pre-aortic ganglia (gut associated)
  
  • Celiac
  • Sup. mesenteric
  • Inf. mesenteric
  • Aorticorenal
  • Renal

Question 7

What are the Basic Features of the Spinal Cord?

Answer 7

Dorsal (Back/Posterior)

• Sensory
  
  • Dorsal horn
  • Dorsal rootlets
  • Dorsal root
  • Dorsal root ganglion
  • Dorsal root ramis

Ventral (Front/Anterior)

• Motor
  
  • Ventral horn
  • Ventral rootlets
  • Ventral root
  • Ventral ramis
• Lateral horn
  
  • Autonomic preganglionic cell bodies
    
    • except: 4 parasym CNs

Question 8

Sensory vs. Motor

Somatic vs. Visceral

Answer 8

• Somatic Sensory
  
  • PPPTT
    
    • Pain
    • Pressure
    • Proprioception
    • Touch
    • Temp
  • Cell body =
    
    • skin/muscles of body wall/limbs
    • dorsal root ganglion
  • Synapse = spinal nerve
• Somatic Motor
  
  • Somatic innervation of the body wall
  • Cell body = spinal nerve
  • Synapse = skin/muscles of body wall/limbs
• Visceral Sensory (same as Somatic)
  
  • Cell body =
    
    • skin/muscles of body wall/limbs
    • dorsal root ganglion
  • Synapse = spinal nerve
• Visceral Motor (Postganglionic Sympathetics)
  
  • Cell body = spinal cord
    
    • thru white r.c.
  • Synapse =
    
    • sympathetic chain or
    • organ

Question 9

What are the characteristics of the Sympathetic Nervous System?

Answer 9

Basics:

• Thoraco-Lumbar Outflow
  
  • T1 - L2
  • 14 pre-ganglionic segments
  • cell bodies = intermedio-lateral cell column
• Pre-ganglionic nerve cell processes exit CNS via:
  
  • ventral root –> spinal nerve
  • spinal nerve –> white ramus communicantes
    
    • 14 white r.c.
  • preganglionic processes –> sympathetic chain

Sympathetic Ganglia Locations:

1. Paravertebral / chain ganglia
   
   • 3 large in cervical region
     
     • Superior
     • Middle
     • Inferior
   • 1 on each ventral ramus in other regions
     
     • Sympathetic chain
2. Preaortic/prevertebral ganglia__​​
   
   • at roots of major arterties branching from abdominal aorta

Question 10

What are the Options of Pre-Ganglionic Processes?

Answer 10

1. Option I:
   
   • Synapse in the chain ganglia
   • Distribute the postganglionic fibers via branches of spinal nerves
2. Option II:
   
   • Travel up/down the chain
   • Synapse above or below T1 & L2
3. Option III:
   
   • Do not synapse at chain ganglia
   • Leave the chain –> splanchnic nerves
     
     • Greater T5-T9/Lesser T10-11/Least T12
4. Option IV:
   
   • Synapse at the ganglia
   • Become splanchnics (regional)

Question 11

Sympathetic Innervation of Thoracic Viscera

Answer 11

Question 12

Sympathetic innervation of Abdominopelvic Viscera

Answer 12

Question 13

General Patterns of the Sympathetics

Answer 13

Question 14

What is the difference between Paravertebral Chain Ganglia & Pre-Aortic (Prevertebral) Ganglia?

Answer 14

Pre-Aortic (Prevertebral) Ganglia

• Do not synapse at sympathetic chain
• Mostly involve GI organs

Question 15

What is the Parasympathetic - Craniosacral Outflow?

Answer 15

Parasympathetic (Feed/Fuck)

• Cranio - from the brain
  
  • preganglionic cell bodies in brainstem
  • associated w/ CN III, VII, IX, X
• Sacral - sacral/pelvic region
  
  • preganglionic cell bodies in spinal cord
  • Segments S2,3,4 = fxn in pelvic region
    
    • aka: pelvic splanchnic nerves

Sympathetic (Fight/Flight)

• Thoracolumbar outflow
  
  • T1 - L2
  • Lungs, Heart, Liver, Kidney, Intestines –> Spleen
• Notes:
  
  • NO PARASYMPATHETIC INNERVATION TO THE BODY WALLS OR LIMBS
    
    • parasympathetic fibers only found on nerves leaving CNS
      
      • CN III, VII, IX, X and S2-4
    • distributed in plexus around organs in the body cavity