GI Autonomic Nervous System

[REVIEW] CNS and PNS

[REVIEW] Multi vs pseudounipolar neurons

[REVIEW] Somatic vs Autonomic Nervous System

1. Describe the location of these neurons’ cell bodies in the somatic system:

   • Pseudounipolar

   • multipolar

2. Differentiate between the posterior and anterior primary ramus

Pseudounipolar neurons:

• dorsal root ganglion with the central process in the dorsal

  root and the peripheral process in the spinal nerve

Multipolar neurons:

• anterior/ventral horn with their axons contributing to

  the spinal nerve and the ventral or dorsal rami.

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Dorsal vs Ventral Primary Ramus:

• posterior (dorsal) primary ramus: back

• anterior (ventral) primary ramus: anterolateral body wall and the extremities.

[REVIEW] Sympathetic vs Parasympathetic

1. Where are the preganglionic neuronal cell bodies of the parasympathetic division?

2. Where are these fibers never found in?

PNS:

• Cell bodies in brainstem nuclei and S2-S4

• parasympathetic fibers are never found in the body wall and limbs.

1. Where are the preganglionic neuronal cell bodies of the Sympathetic division?

2. What is the first postganglionic target?

• Lateral horn/intermediolateral cell column (IMLCC) of spinal cord segments T1-L2.

• Among the first postganglionic targets are series of interconnected ganglia on each side of the vertebral column - paravertebral sympathetic trunk

1. [REVIEW] Describe the path of the Visceral Efferent Fibers (sympathetic)

   • General path

   • Path towards skin and blood vessels

   • Thoracic Cavity

   • Abdominapelvic Cavity

2. Describe the path of Visceral Afferent Fibers

Visceral efferent fibers:

• Cell bodies @ IMLCC → Ventral Root → Spinal N → Ventral Rami → White Rami communicates → sympathetic ganglia (can synapse or pass through)

• To Glands of Skin and SM of blood vessels: From sympathetic trunk → Gray Rami → ventral rami

• Thoracic Cavity: Synapse @ Sympathetic paravertebral ganglia

• Abdominaopelvic Cavity: No Synpase @ Sympathetic Trunk → Pass through Sympathetic Trunk as abdominolpelvic splanchnic nerves( preganglionic fibers) → Synpase @ prevertebral ganglia around aorta branches

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Visceral Afferent Fibers:

accompany visceral efferent fibers from the visceral organs to the spinal nerve; their cell bodies are found in the posterior/dorsal root ganglia.

Describe the generalization explaining the NS of the Digestive System

The digestive system and other abdominal organs are innervated by autonomic nerve fibers from both the sympathetic and parasympathetic nervous systems

• Nerve fibers travel along blood vessels to reach their target organs

LIst out the prevertebral ganglia for the sympathetic NS

• Celiac trunk – celiac ganglia

• Superior mesenteric artery – superior mesenteric ganglion

• Inferior mesenteric artery – inferior mesenteric ganglio

Describe the pathway of the Parasympathetic NS

Vagus N.: Brain/Spinal Cord → Vagus N. carries Afferent/Efferent (from the dorsal motor nucleus of the vagus in the medulla oblongata) → enters abdomen through esophageal hiatus

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Pelvic Splanchnic N.:

• arise from cell bodies in the spinal cord at S2-S4 in the same area as IMLCC but do not form a discreet structure.

• Preganglionic fibers reach the wall of the viscera via mesenteries and synapse with short postganglionic neurons with cell bodies in the wall of the viscera:

  • Myenteric (Auerbach’s) plexus

  • Submucous (Meissner’s) plexus

In regards to Hirschsprung disease:

• What gene is involved

• Why is there dilation?

• mutations in the RET gene,

  • tyrosine kinase receptor involved in neural crest migration

• dilation is due to failure of peristalsis in the aganglionic segment

[REVIEW] Achalasia

[REVIEW] Referred Pain

Describe why the pain changes in appendicitis