Autonomic Nervous System Flashcards
Functional Definition of ANS
controls involuntary visceral activity in order to maintain homeostasis or respond to stress
Anatomical Definition of ANS
- General Visceral Efferent system
- General Visceral Afferents
- components of CNS that regulate visceral activity
General Visceral Efferent (GVE) System
- Divided physiologically and anatomically into 2 components
- Sympathetic
- Parasympathetic
Sympathetic
- fight or flight
- thoracolumbar
Parasympathetic
- homeostasis -> “rest & digest”
- craniosacral
The GVE system is a 2 neuron pathway. What does that involve?
- takes 2 neurons to get from CNS to effector
- Ganglion provides the synapse location (Not same ganglion for sym and parasym!)
- Thus has a preganglionic component and a postganglionic component
The first part of the sympathetic nervous system is ALWAYS the same. What is it?
lateral gray horn -> ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk
Parasympathetic Nervous System
CN III, VII, IX
covered with head
Parasympathetic Nervous System CN X (vagus n.)
thoracic and abdominal viscera
Parasympathetic Nervous System
Sacral Spinal Cord
pelvic viscera
Sympathetic Pathway
Body Walls and Limbs
Preganglionic Pathway: lateral gray horn (of T1-L5 ) → ventral root → spinal nerve → ramus communicans → sympathetic trunk →
Ganglion: sympathetic trunk ganglia →
Postganglionic Pathway: rami communicantes to spinal nerves → dorsal or ventral branches of spinal nerves
Sympathetic Pathway
Head
Preganglionic Pathway: lateral gray horn (of ~T1-T3) → ventral root → spinal nerve → ramus communicans → sympathetic trunk → ansa subclavia → cervical sympathetic trunk (vagosympathetic trunk) →
Ganglion:cranial cervical ganglion →
Postganglionic Pathway:internal and external carotid nerve plexuses (nerves follow blood supply to the head)
Sympathetic Pathway
Neck
Preganglionic Pathway: lateral gray horn (of ~T3-T5) → ventral root → spinal nerve → ramus communicans → sympathetic trunk →
Ganglion:cervicothoracic ganglion →
Postganglionic Pathway:vertebral nerve → rami communicantes to cervical spinal nerves → dorsal or ventral branches of cervical spinal nerves
Sympathetic Pathway
Thorax
Preganglionic Pathway: lateral gray horn (of ~T5-T8) → ventral root → spinal nerve → ramus communicans → sympathetic trunk → [ansa subclavia]
Ganglion:cervicothroracic ganglion [or middle cervical ganglion] →
Postganglionic Pathway:branches from ansa subclavia [or branches coursing with vagus nerve]
Sympathetic Pathway
Abdominal Caivty
Preganglionic Pathway: lateral gray horn (of ~T7-L2) → ventral root → spinal nerve → ramus communicans → sympathetic trunk → major, minor, or lumbar splanchnic nerves
Ganglion: prevertebral ganglia within plexuses (celiacomesenteric ganglion, caudal mesenteric ganglion, others) →
Postganglionic Pathway: nerve plexuses on abdominal vessels (nerves follow blood supply to abdominal viscera)
Sympathetic Pathway
Pelvic Cavity
Preganglionic Pathway: lateral gray horn (of lumbar cord segments) → ventral root → spinal nerve → ramus communicans → sympathetic trunk → lumbar splanchnic nerves →
Ganglion: caudal mesenteric ganglion →
Postganglionic Pathway: left/right hypogastric nerves → pelvic plexus → [branches which follow blood vessels to pelvic viscera]
Parasympathetic Pathway
Vagus Nerve
Thorax
Preganglionic Pathway: parasympathetic nucleus of vagus nerve → vagus nerve → vagosympathetic trunk → vagus nerve → vagal branches to heart, lungs, etc (cardiac nerves) [recurrent laryngeal nerves]
Ganglion: terminal ganglia (within organs innervated) →
Postganglionic Pathway: within organ
Parasympathetic Pathway
Vagus Nerve
Abdomen
Preganglionic Pathway: parasympathetic nucleus of vagus nerve → vagus nerve → vagosympathetic trunk → vagus nerve → dorsal & ventral vagal branches → dorsal & ventral vagal trunks → dorsal vagal trunk joins celiacomesenteric plexus via celiac branch, ventral vagal trunk goes directly to stomach and liver
Ganglion: terminal ganglia (within organs innervated) →
Postganglionic Pathway: within organ
Parasympathetic Pathway
Sacral Spinal Cord
Preganglionic Pathway: intermediate gray matter (of S1-S3) → ventral root → spinal nerve → ventral branch → lumbosacral plexus → pelvic nerve → pelvic plexus
Ganglion: pelvic ganglia within pelvic plexus →
Postganglionic Pathway: branches from pelvic plexus to pelvic viscera
