Autonomic nervous system Flashcards
What is the main function of the autonomic nervous system?
Controls involuntary visceral activity to maintain homeostasis or respond to stress
What components form the autonomic nervous system?
General visceral efferent nerves
General visceral afferent nerves
Components of CNS that regulate visceral activity by receiving or sending signals to GVE & GVA systems
What are the 2 branches of of the General Vsceral Efferent nervous system?
Sympathetic: fight or flight (thoracolumbar)
Parasympathetic: Rest and Digest (Craniosacral)
Do any autonomic nerves come off the cervical region?
No
There are 2 neuronal components that form both the divisions of the General Visceral Efferent System, what are they?
A preganglionic component
A post ganglionic component
What are pre ganglionic & post ganglionic components?
Pre-ganglionic: Axon exits spinal cord and synapses on post-ganglionic cell body
Post-ganglionic: Pre-ganglionic component synapses on cell body, and post-ganglionic axon innervates Effector muscle
How do the pre- and post-ganglionic components differ between Para- and Sympa- systems?
Sympathetic: Equal sized pre- and post-ganglionic portions. Post-ganglionic cell body located outside the organ wall
Parasympathetic: Long pre-ganglionic aspect, post-ganglionic cell body & axon is located in the organ wall
The sympathetic pathway always starts the same, describe the signal flow
Lateral grey horn -> Ventral root -> spinal nerve -> ramus communicans -> Sympathetic trunk
Describe sympathetic signal flow for the body wall & limbs
Lateral grey horn -> Ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk -> ganglion sympathetic trunk ganglia -> post (other sympathetic trunk rami -> other spinal nerves) or continue down ventral branch of spinal nerve after sympathetic trunk ganglion
Do all spinal nerves have a GVE and GVA branch?
Yes, both the dorsal branch and ventral branch of a spinal nerve are mixed
What is the communicating branch of the sympathetic nervous system?
Ramus communicans
Branches off the spinal nerve
What are paravertebral ganglion?
Sympathetic trunk ganglion
Describe the sympathetic pathway for the head
Lateral grey horn -> ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk -> Ansa subclavia -> vagosympathetic trunk -> ganglion cranical cervical ganglion -> post internal & external carotid nerve plexus
Describe the sympathetic pathway for the neck
Lateral grey horn -> ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk -> ganglion cervicothoracic ganglion -> post vertebral nerve -> rami communicates to cervical spinal nerves -> dorsal/ventral branches of cervical spinal nerves
Describe the sympathetic pathway for the thorax
Lateral grey horn -> ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk -> ansa subclavia -> ganglion cervicothoracic ganglion or middle cervical ganglion -> post branches from ansa subclavia or courses with vagus nerve
Describe the sympathetic pathway for the abdominal cavity
Lateral grey horn -> ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk -> major, minor, lumbar splanchnic nerves -> ganglion celiacomesenteric ganglion & plexus -> nerve plexus on abdominal muscles
Describe the sympathetic pathway for the pelvic cavity
Lateral grey horn -> ventral root -> spinal nerve -> ramus communicans -> sympathetic trunk -> lumbar splanchnic nerves -> ganglion caudal mesenteric ganglion -> post hypogastric nerves -> pelvic plexus -> branches that follow blood vessels to pelvic viscera
What is the last sympathetic ganglion?
Caudal mesenteric ganglion
What is the only nerve that comes fro the caudal mesenteric ganglion?
Left & Right hypogastric nerves
The parasympathetic system is composed of which nerves?
Cranial nerves III, VII, IX, X (vagus), sacral spinal cord
What parasympathetic nerves innervate the head?
Cranial nerves III, VII, and IX
What parasympathetic nerves innervate the thoracic and abdominal viscera?
Cranial nerve X (vagus)
What parasympathetic nerves innervate the pelvic viscera?
Sacral spinal cord
Describe the pathway of the vagus nerve to the thorax/cervical region
Parasympathetic Nucleus of vagus nerve -> vagus nerve -> vagosympathetic trunk -> vagus nerve -> vagal branches to heart, lungs, recurrent laryngeal nerves -> ganglion terminal ganglia within organs -> post axon in organ wall
Describe the pathway of the vagus nerve to the abdominal region
Parasympathetic Nucleus of the vagus nerve -> vagus nerve -> vagosympathetic trunk -> vagus nerve -> dorsal & ventral vagal branches -> dorsal & ventral vagal trunks -> dorsal vagal trunk joins celiacomesenteric plexus, ventral vagal trunk goes directly to stomach & liver -> ganglion terminal ganglia within organ -> post axon in organ wall
Does the dorsal vaga trunk synpase on the celiacomesenteric nerve plexus?
No, it joins the celiacomesenteric plexus via the celiac branch
What are the 2 branches of the celiacomesenteric plexus and what organs do they innervate
Celiac plexus: stomach, spleen, liver, gallbladder, pancreas
Cranial mesenteric plexus: small intestines, cecum, ascending & transverse colon
What is the pathway of the sacral spinal cord to the pelvis viscera?
Intermediate gray matter of S1 - S3 -> ventral root -> spinal nerve -> ventral branch -> lumbosacral plexus -> pelvic nerve -> pelvis plexus -> ganglion pelvic ganglia in pelvic plexus -> post branches from pelvic plexus to pelvic viscera
Why can nerves pass through a plexus without synapsing?
Nerves will wait to synapse until the last possible ganglion within the pathway
What segments do parasympathetic nerves originate in?
Brainstem (cranial nerves III, VII, IX, X) and Sacral spinal segments S2, S3, S4
What spinal cord segments do sympathetic nerves originate in?
T1 to L2 (Thoracolumbar)
What is the cutaneous area?
Entire area of the skin that is innervated by a nerve
What is the autonomous zone?
Area of skin that is innervated solely by a specific nerve with no overlap from adjacent nerves
There are 4 nerve* and vessel branches in the fore paw, what are they?
Superficial dorsal common digital, superficial palmar common digital
Deep dorsal metacarpal (vessels only, no nerves)
Deep palmar metacarpal
What cervical nerve becomes the phrenic nerve?
Deep branch of C5
What are the 2 branchs of C2?
Great auricular nerve, transverse cervical nerve
What is the endothoracic fascia?
Fascia of the thorax that supports all serosal layers and gives strength to thoracic ligaments
