Nervous System Part 1 Flashcards
What makes up the Central Nervous System?
The brain and spinal cord
What makes up the Peripheral Nervous System?
Peripheral Nerves and Ganglia (clusters of nerve cell bodies that makes a swelling)
A swelling due to a cluster of neurons collecting in one area that carries sensory information from the peripheral aspects of the body into the CNS.
Dorsal Root Ganglia
A swelling due to a cluster of neurons collecting in one area that carries motor information to the peripheral aspects of the body.
Ventral Root Ganglia
Occurs when the Ventral and Dorsal Roots join together. Has sensory and motor functions.
Spinal Nerve
How many spinal nerves are there?
31 pairs
Spinal nerves very quickly divide into two components; one goes anterolaterally and the other goes dorsally/posteriorly
Dorsal or Ventral Primary Rami
Which Rami are the largest and take care of most everything?
Ventral Primary Rami
The Dorsal/Ventral Primary Rami go on to form what? Ex: Cervical Plexus is made up of VPR of C1-C5
Peripheral Nerve Branches
Receptors located on skin, joints, muscles experience a threshold stimulus that creates an action potential along the dorsal root, which enters the Spinal Cord. Spinal cord then absorbs the dorsal roots, ending with neuron sprouts coming out (Synapsing) with the ventral root.
Afferent (Sensory)
The Ventral root ganglion is located where?
Within the spinal cord
The Dorsal root ganglion is located where?
Outside the spinal cord
After synapsing with the Dorsal Root, the Spinal cord responds by sending the message out over the Ventral root (motor). Ventral root supplies response to something like a skeletal muscle.
Efferent (motor)
Most peripheral nerves are what?
Mixed (motor & sensory functions)
A component of the Peripheral Nervous System (PNS); 12 pairs coming directly off of the brain (except for one)
Cranial Nerves
Axons that deliver information to muscles that:
-have large diameters
-are heavily myelinated
-Rapidly conduct signals
Run very fast so that we can get proper responses from muscles to help us maintain posture, etc.
Somatic Efferent Fibers (motor fibers to skeletal muscles)
Supplies motor innervation to the viscera (GI tract, esophagus, stomach, cardiac, etc). Has a parasympathetic and sympathetic component.
-Entirely motor, no sensory functions
Autonomic Nervous System (ANS)
Motor fibers that have:
-a small diameter
-little to no myelin
-a slow conduction
-a two-tiered system involving preganglionic and postganglionic schema
Autonomic Nervous System (parasympathetic or sympathetic)
Fibers that originate within a nucleus (nerve cell cluster) located within the CNS (brain, spinal cord, CNs, etc).
These give off a preganglionic axon that goes into the periphery to synapse with a ganglionic structure.
Preganglionic Fibers
Fibers that originate within a ganglion (nerve cell cluster) that is located outside of the CNS. Gives off a postganglionic axon that projects to visceral structures to innervate them.
Postganglionic Fibers
1st order neuron gives off an axon that is going to synapse with a 2nd order neuron that is located within a ganglion. Then, 2nd order neuron gives off a postganglionic axon that projects to whatever the target organ is (visceral smooth muscle, cardiac muscle) to have sympathetic or parasympathetic response.
ANS Preganglionic/Postganglionic Schematic
Has a short preganglionic neuron and a long postganglionic neuron
Sympathetic