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Nervous System I Cheat Sheet by

Basics of both the CNS and PNS

NS Function and Divisions

What are the functions of the NS?
Sensation, integr­ation, response
What are the divisions and subdiv­isions of the NS?
CNS and PNS (in PNS: somatic sensory, visceral sensory, somatic motor, and the autonomic nervous system which has the parasy­mpa­thetic and sympat­hetic nervous systems)

Nervous Tissue

What are the charac­ter­istics of neurons?
1. Highly specia­lized to conduct nerve impulses 2. Long lived 3. Don't divide 4. High metabolic rate (takes a lot of energy)
What are the structures of neurons?
Neurosoma (cell body), dendrites (recei­vers), axons (senders)
Describe sensory neurons
bring info to the CNS
Describe intern­eurons
integrate inform­ation IN THE CNS
Describe motor neurons
responses leaving the CNS
What is the most common neuronal variety throughout the body?
Multipolar neurons


What are the 6 types of neuroglia?
CNS: Astroc­ytes, microg­lial, ependymal cells, and oligod­end­rocytes PNS: Satellite cells and schwann cells
What is the function of astroc­ytes?
Support, control ionic enviro­nment, nouris­hment, commun­ica­tion, it has many varied in functi­onality
What is the function of microglial cells?
Phagoc­ytosis- remove debris, immune function
What is the function of ependymal cells?
Involved in the production and circul­ation of cerebr­ospinal fluid
What is the function of oligod­end­roc­ytes?
Form the myelin­ation in the CNS for insulation
What is the function of satellite cells?
Support and enviro­nmental regulation (surround neuros­omas)
What is the function of schwann cells?
For myelin­ation in the PNS for insulation
What is myelin?
A plasma membrane of water, lipids, and proteins that insulates axons
What is the functi­on/­benefit of myelin?
Increases the speed of conduction (gaps are necessary)
What influences conduction speed?
The diameter of the nerve fiber and myelin

General NS Organi­zation

What is the difference between gray and white matter?
Gray matter lacks myelin
Where is gray/white matter in the spinal cord?
Gray: inner portion White: outer portion
Where is gray/white matter located in the brain?
Gray: Cortex (cerebrum and cerebe­llum), superf­icial White: tracts, deep to cortex Brain Nuclei: deep clusters of gray matter embedded in white matter

Spinal Cord Structure

What are the functions of the spinal cord?
1. Conduc­tion- carry impulses up and down 2. Neural Integr­ation- decision making 3. Locomo­tion- simple patterns like walking 4. Reflexes- quick reaction without brain
What are the major structures of the spinal cord?
Cervical enlarg­ement, lumbar enlarg­ement, conus medullaris (end of the spinal cord), cauda equina (horse tail), and terminal filum (anchors conus medull­aris)
What are the regions of the spinal cord?
Cervical, thoracic, lumbar, sacral
Describe the posterior (dorsal) horn
Sensory processing (sensory neurons)
Describe the anterior (ventral) horn
Send motor signals (motor neurons)
Describe the gray commisure
connects the right and left side of the spinal cord and allows for side to side inform­ation transfer
Describe the lateral horn
ONLY in thoracic and lumbar region of SC, for autonomic nervous system (speci­fically the sympat­hetic division)
Describe the dorsal (poste­rior) funiculus
ascending tracts (sensory info up to the brain)
Describe the ventral (anterior) funiculus
descending tracts (motor commands down from the brain) and a little ascending
Describe the lateral funiculus
ascending and descending tracts
What is the function of commis­sural fibers in white matter of the spinal cord?
carry inform­ation from side to side

Protection of the Spinal Cord

What protects the spinal cord?
1. Vertebral column 2. Meninges 3. Cerebr­ospinal fluid (CSF)
What are meninges?
protective membranes
What are the functions of the meninges?
1. Cover and protect the CNS 2. Separate soft tissue from bone
What are the layers of the meninges?
1. Dura mater 2. Arachnoid Mater 3. Pia Mater
What are the structures associated with the dura mater?
Dural sheath and the epidural space (fat filled [cushi­ons])
What are the structures associated with the arachnoid mater?
Subara­chnoid space (CSF and blood vessels)
What are the structures associated with the Pia Mater?
Terminal filum
What is the function of the dura mater?
Outer coveri­ng-­pro­tection
What is the function of the arachnoid mater?
Middle layer- subdural space
What is the function of the pia mater?
Internal layer- thin membrane that is clingy and well vascul­arized (nouri­shing)
What are the functions of CSF?
Cushio­n/f­loats CNS, removes waste, and circulates nutrients

Nervou­s/S­pinal Nerves

What is a nerve?
Bundles of axons
What structures make up nerves?
Epineurium (outer covering), perine­urium (surrounds nerve fascic­les), and endone­urium (surrounds individual nerve fiber
What are ganglia?
clusters of cell bodies NOT in CNS
What are spinal nerves?
31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
What are the general structures of spinal nerves?
Rootlets, ventral root, dorsal root, and dorsal root ganglion
What is a nerve plexus?
networ­k/web of nerves
What are the major plexuses?
Cervical plexus (C1-C4), Brachial plexus (C5-T1), Lumbar plexus (L1-L5), Sacral plexus (L4-S4)
What are the major nerves of the cervical plexus?
Phrenic nerve-­dia­phragm
What are the major nerves of the brachial plexus?
Axillary, radial, median, and ulnar
What are the major nerves of the lumbar plexus?
Femoral and obturator
What are the major nerves of the sacral plexus?
Sciatic nerve (tibial, fibular)
What does the cervical plexus innervate?
Skin and muscles of the neck
What does the brachial plexus innervate?
Neck, axilla, and the arm
What does the lumbar plexus innervate?
Anterior and medial thigh
What does the sacral plexus innervate?
Posterior thigh and the lower limb
What is a reflex?
a response to a stimul­ation
What are the charac­ter­istics of a reflex and how does it work?
1. Stimul­ation (requires) 2. Fast (spinal cord and back) 3. Involu­ntary 4. Stereo­typed (every time you do it, you get the same response)

The Brain

What are the main functions of the brain?
1. Initiates voluntary and involu­ntary movement 2. Interprets and integrates sensory stimul­ation 3. Consci­ousness and cognitive function 4. Controls basic life sustaining activities
How is the brain organized?
Cerebrum, Cerebe­llum, Dience­phalon, and Brain Stem
Describe the layers of protection for the brain
1. Skull 2. Meninges 3. CSF 4. Blood Brain Barrier
What are ventri­cles?
open chambers in the brain
List the order of the circul­ation through the ventricles
Starts in lateral ventri­cles, continues to the third ventricle, continues into the fourth ventricle, and goes into central canal of the spinal cord

The Brainstem

Where is the brainstem located?
at the base of the brain
What structures make up the brain stem?
Pons, medulla oblongata, and midbrain
What structures make up the medulla oblongata and where is it located?
Nuclei and tracts, located continuous with the spinal cord (caudal to stem)
What is the function of the medulla oblongata?
Relay info, cardiac center, vasomotor center, respir­atory center, and convey info. Has cranial nerves IX-XII
What structures make up the pons and where is it located?
Bulge, cerebellar peduncles, tracts, and nuclei. Located between medulla and midbrain
What is the function of the pons?
Carry signals up and down brainstem and connect right and left cerebellar hemisp­heres. Has cranial nerves V-VII
What structures makeup the midbrain and where is it located?
Nuclei, tectum (roof), cerebral aqueduct, tegmentum (floor), cerebral crura. Located in the rostral portion of the brainstem
What is the function of the midbrain?
Visual reflex­es/­int­egr­ation, proces­s/relay auditory signals, fine motor control, voluntary movement. Contains cranial nerves III and IV

The Dience­phalon

Where is the dience­phalon located?
Deep to the cerebrum, superior to the brainstem, and surrounds the third ventricle
What structures makeup the dience­phalon?
Thalamus, hypoth­alamus, and epitha­lamus
What is the function of the thalamus?
Gateway to cortex: filter­/relay sensory info (all but smell), motor control (relay info between cerebrum and cerebe­llum), and memory and emotional
What is the function of the hypoth­alamus?
Main control center of ANS: regulates homeos­tasis (hormone secretion, thermo­reg­ula­tion, food/water intake, sleep/­cir­cadian rhythms, emotion and sexual respon­ses), memory (involved in memory formation)
What is the function fo the epitha­lamus?
Sleep-wake cycle (circa­dia­n/s­easonal cycles) and relay

The Cerebellum

Where is the cerebellum located?
Inferi­or/­pos­terior to cerebrum, dorsal to pons
What structures make up the cerebe­llum?
Cerebellar hemisp­heres, cortex, folia (folds), arbor vitae (white matter), deep nuclei, cerebellar peduncles
What is the function of the cerebe­llum?
Subcon­scious evaluation of sensory input, coordinate and smooth movements, maintain posture and equili­brium, some cognitive skills (muscle memory)

The Cerebrum

What are the major structures that make up the cerebrum?
Cerebral cortex, cerebral white matter, nuclei, right and left hemisp­heres (separated by the longit­udinal fissure and connected by the corpus callosum) and the transverse fissure (separates the cerebrum and cerebe­llum)
Describe the associ­ation tracts
one part of a hemisphere to another
The limbic system is...
the major emotion and learning center
What are functional areas of the cerebral cortex
Locali­zation of specific functions
What are the two specific functional areas of the cerebral cortex?
The primary cortex (sensory and motor) and the associ­ation cortex
What are cranial nerves?
Nerves that arise directly from the brain (primarily base)
What are the different types of cranial nerves?
Motor: III, IV, VI, XI, XII Sensory: I, II, VIII and Mixed: V, VII, IX, X

Functional Areas Image


Autonomic Nervous System

What are the functions of the ANS?
Homeos­tasis aka regulation
What are the divisions of the ANS?
Sympat­hetic and Parasy­mpa­thetic nervous systems
What is the function of the sympat­hetic nervous system?
Fight or flight
What is the function of the parasy­mpa­thetic nervous system?
Rest and digest (homeo­stasis)
What structures are associated with the sympat­hetic NS?
Smooth muscle in blood vessels, skin (raises hairs), sweat glands, and adrenal glands (epine­phrine and norepi­nep­hrine secretion)
What structures are associated with the parasy­mpa­thetic NS?
head/n­eck­/th­ora­x/a­bdomen and the digestive tract & pelvic organs
How do the sympat­hetic and parasy­mpa­thetic divisions differ?
Sympat­hetic division has short pregan­glionic fibers and long postga­ngl­ionic fibers while the parasy­mpa­thetic division has long pregan­glionic fibers and short postga­ngl­ionic fibers
How does the sympat­hetic and parasy­mpa­thetic divisions differ from the somatic motor division?
The somatic motor division only has one ganglionic fiber
What is dual innerv­ation?
sympat­hetic and parasy­mpa­thetic divisions have antago­nistic effects in working together
What is the enteric nervous system?
Nerve plexuses embedded in the wall of the digestive tract
What is the function of the enteric nervous system?
Motility and secretion of enzyme­s/acids

Somatic Neural Pathway

Use this and following images to describe the differ­ences with somatic motor and autonomic systems

Sympat­hetic Neural Pathway

Use previous image and following image to contrast differ­ences

Parasy­mpa­thetic Neural Pathway

Use previous images to contrast


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