peripheral nervous system - somatic and autonomic

ventral root

motor output from the spinal cord arising from neurons in ventral spinal cord. Axons leave via a ventral root and terminate on skeletal/smooth muscles

dorsal root

sensory input into dorsal spinal cord arising from neurons in the dorsal root ganglia

spinal nerves

combination of sensory and motor axons (ventral and dorsal roots)

somatic nervous system

responsible for carrying motor commands from the spinal cord to skeletal muscle and carrying sensory information from body wall/muscles back to spinal cord

• responsible for producing contractions of skeletal (voluntary) muscles and processing sensory information that arrives as external stimulus

nerves

made up of axons of hundreds/thousands of individual neurons, made up of morphologically and functionally distinct types of axons

endoneurium

individuals axons are surrounded by connective tissue

perineurium

multiple bundles are grouped together by this connective tissue sheath

epineurium

all bundles are enclosed by common thick external connective sheath

efferent

axons that conduct information away from the CNS; cell bodies located within the spinal cord

spinal somatic motor

outgoing axons carrying motor commands to skeletal muscles; large diameter and heavily myelinated

spinal visceral motor

ANS - outgoing axons carrying motor commands that are involved in innervating smooth muscle, cardiac muscle, and glandular tissue - small diameter and lightly myelinated

afferent

axons that conduct information towards the CNS, cell bodies are located in a dorsal root ganglion

spinal somatic sensory

axons that transmit sensory information from the body to the spinal cord; large diameter and heavily myelinated s

spinal visceral sensory

axons that transmit sensory information from organs to the spinal cord

cranial nerves

not formed from dorsal and ventral roots (not present in brainstem); some carry only motor info., some carry only sensory info., and some carry both sensory and motor info.

cranial somatic motor

skeletal muscles in head and neck

cranial visceral motor

ANS - glandular structures in head; smooth muscles in thorax and abdomen

cranial somatic sensory

axons that transmit sensory information from face, ear, oral cavity

cranial visceral sensory

axons that transmit sensory info. from internal organs to the brainstem

special sensory

cranial nerves - sensory information unique to head (vision, hearing, taste, smell, balance)

branchial motor

cranial nerves - unique voluntary muscles which have different embryological origin; these muscles are not derived from somites but rather from structures called pharyngeal arches

autonomic nervous system

portion of the nervous system that supplies motor and sensory innervation to structures not under voluntary control

sympathetic NS

prepare body for emergency; no stimulation in the digestion

parasympathetic NS

conserve and restore energy; maintain homeostasis; no parasympathetic connections in the periphery or head

autonomic nervous system motor circuit

ANS requires 2 neurons to elicit a response in a target organ

pre-ganglionic neuron

1st neuron in ANS system; always located within the CNS

post-ganglionic neuron

2ns neuron in ANS system; always in a ganglia located in periphery

note: (not dorsal root ganglion - that area contains sensory info!)

sympathetic chain

collateral ganglion

location of sympathetic post-gangalionic neurons

sympathetic chain

bilateral para vertebral ganglia that is adjacent to vertebral column; extend from base of skull to coccyx

rami communicate

sympathetic chain ganglia are attached to adjacent spinal nerves by this feature

collateral ganglion

located around the abdominal aorta; houses post-ganglionic sympathetic neurons

between T1 and L2

pre-ganglionic sympathetic neurons are located on the spinal cord between these two areas (thoracolumbar division = sympathetic nervous system)

pre-ganglion neuron

ventral root

sympathetic chain

rami communicante

post-ganglionic neurons

abdomen

collateral ganglia

the axons of all BLANK BLANK leave the spinal cord via the BLANK BLANK and enter the BLANK BLANK via BLANK BLANK, where they synapse onto BLANK BLANK or continue to the BLANK to the BLANK BLANK

pre-ganglionic neurons

ventral root

sympathetic chain

rami communicante

post-ganglionic neurons

periphery

“run-the-chain”

the axons of all BLANK BLANK leave the spinal cord via the BLANK BLANK and enter the BLANK BLANK via BLANK BLANK, where they synapse onto BLANK BLANK at a DIFFERENT LEVEL, which re-enters the spinal nerve to reach target cells in the BLANK

pre-ganglionic neurons

ventral root

sympathetic chain

rami communicante

rami communicante

collateral ganglion

abdomen

“abdominal viscera”

the axons of all BLANK BLANK leave the spinal cord via the BLANK BLANK and enter the BLANK BLANK via BLANK BLANK. The pre-ganglionic neurons branch off at BLANK BLANK and travel to the BLANK BLANK, which is located in the BLANK to innervate internal organs in that region

pre-ganglion neurons

ventral root

sympathetic chain

rami communicante

post-ganglionic neurons

thoracic

“thoracic viscera”

the axons of all BLANK BLANK leave the spinal cord via the BLANK BLANK and enter the BLANK BLANK via BLANK BLANK. The pre-ganglionic neurons synapse into BLANK BLANK here, which travel out of the sympathetic chain and travel to the BLANK region to innervate internal organs there

brainstem

sacral - between S2 and S4

pre-ganglionic PARASYMPATHETIC neurons are located here (craniosacral division = Para. NS)

location of post-ganglionic parasympathetic ganglia

in most areas, these neurons are located in walls of organ being innervated

distension/pressure in hollow organ

pain

sensory fibers innervating viscera relay information to the CNS about this:

ganglia in the head

sensory cells that give rise to axons that accompany the Parasympathetic nerves to viserca are located here

DRG

sensory cells that give rise to axons that accompany sympathetic nerves to viscera are located here

characteristics of visceral pain

1. not evoked by all viscera - not all viscera is innervated by sensory fibers

2. referred to body wall - convergence of viscerosensory and somatosensory fibers in central pain pathway

3. diffuse and poorly localized - few sensory fibers and extensive divergence in CNS