Organization of the Nervous System Flashcards
CNS is composed of
Brain and Spinal cord
PNS consist of
cranial, spinal n., and their associated ganglia
CNS main centers where correlation and integration of the nervous system occurs
Brain and the spinal cord
System of membranes that covers the spinal cord and brain
Meninges
Brain and spinal cord is suspended to
CSF
Excitable nerve cells of the CNS
Neurons
Processes of neurons
Axons or nerve fibers
Protects the meninges
Skull & vertebral column
Neurons are supported by specialized tissue
Neuroglia
CNS Gray matter consist of
nerve cells embedded in neuroglia
CNS White matter consist of
nerve fibers embedded in neuroglia
CNS White matter is white d/t the presence of lipid material in the n. fibers
Myelin sheaths
Axons are relatively __ and commonly __
unprotected; trauma
Part of the nervous system that innervates the body’s involuntary structure
ANS
2 parts of ANS
sympathetic & parasympathetic
ANS: prepare the body for emergency
sympathetic
ANS: Aimed at conserving and restoring energy
parasympathetic
Spinal cord is situated withing
Vertebral canal of the vertebral column
Spinal cord is surrounded by 3 meninges
dura mater, arachnoid mater, pia mater
Surrounds the spinal cord for further protection
CSF
CSF found on
Subarachnoid space
Shape of the spinal cord
roughly cylindrical
Spinal cord begins superiorly in the __
Medulla oblongata in the skull
Spinal cord terminates inferiorly at the
Lower border of L1
Spinal cord tapers off into the
Conus medullaris from the apex of which filum terminale descends to attach to the back of the coccyx
Prolongation of the pia mater
Filum terminale
where do filum terminale attaches
Back of the coccyx
Gives rise to the peripheral and central nerve fibers
Posterior Root Ganglion
How many pairs of spinal nerves
31
31 spinal nerves are attached by
anterior/motor roots; posterior/sensory roots
Each root is attached to the cord by a __
series of rootlet
Posterior nerve root possesses a __
Posterior root ganglion
Brain = inner:__ mater; outer;__ mater
Inner white; outer gray
Brain = inner:__ matter; outer;__ matter
Inner white; outer gray
Spinal: The gray matter is seen on a cross section as an H-shaped pillar called
anterior and posterior gray columns or horns
Spinal gray commissure contains the
small central canal
anterior and posterior gray columns or horns is united by thin
gray commissure
Spinal white matter is divide into
anterior, lateral, and posterior white column
Brain lies in the __ cavity
cranial
brain is continuous with the spinal cord in the
foramen magnum
3 meninges of the brain
dura mater, arachnoid mater, pia mater
CSF surrounds the brain in the __ space
Subarachnoid
3 major divisions of the brain
hindbrain, midbrain, forebrain
Brainstem is the collective term of
medulla oblongata, pons, midbrain
Hindbrain comprises the
Medulla oblongata, pons, cerebellum
Shape of the medulla oblongata
Conical
Medulla oblongata connects __ superiorly
pons
Medulla oblongata connects __ inferiorly
spinal cord
Medulla oblongata collection of neurons
nuclei
Serves as a conduit for ascending and descending nerve fibers
Medulla oblongata
Pons is situated on the
anterior surface of the cerebellum
Pons is inferior to the
midbrain
Pons is superior to the
medulla oblongata
Derives its name from the large number of transverse fibers on its anterior aspect
pons/bridge
Cerebellum lies within the
Posterior cranial fossa of the skull
Cerebellum is posterior to the __ and the __
Pons and the medulla oblongata
Cerebellum consist of 2 laterally place hemispheres connected by a median portion called __
Vermis
Cerebellum is connected to the midbrain by
SCP
Cerebellum is connected to the pons by
MCP
Cerebellum is connected to the medulla by
ICP
Composed of large bundles of nerve fibers connecting the cerebellum to the remainder of the nervous system
Peduncles
Surface layer of each cerebellar hemisphere is called
cortex
Composition of cortex
Gray matter
The cerebellar cortex is thrown into __ separated by __
Folds or folia; transverse fissures
Largest gray matter embedded in the white matter (Cerebellum)
Dentate nuclei
The medulla oblongata, the pons, and the cerebellum surround a cavity filled w/ CSF called
4th ventricle
4th ventricle is connected superiorly to the __ by the __
3rd ventricle; cerebral aqueduct
4th ventricle is inferiorly connected to __
Central canal of the spinal cord
4th Ventricle communicates with the subarachnoid space through
3 openings in the inferior part of the roof
Narrow part of the brain that connects the forebrain and the hindbrain
midbrain
Narrow cavity of the midbrain
cerebral aqueduct
Forebrain comprises the
diencephalon
Central part of the forebrain and the cerebrum
Diencephalon
Diencephalon is consist of
Ventral hypothalamus, dorsal thalamus
Shape of the thalamus
egg
Large, egg shaped mass of gray matter that lies on the either side of the third ventricle
Thalamus
__ end of the thalamus forms the __ boundary of the __
anterior, posterior, interventricular foramen
Opening between the third and lateral ventricles
Interventricular foramen
Hypothalamus forms the __ part of the __ wall and the __ of the __ ventricle
lower, lateral, floor, third
Largest part of the brain
Cerebrum
2 CEREBRAL HEMISPHERES connected by a mass of white matter called
Corpus callosum
Cerebrum is superior to
anterior and middle cranial fossae
Posteriorly, Cerebrum lies above the
tentorium cerebelli
The hemisphere is separated by a deep cleft
Longitudinal fissure
Longitudinal fissure projects thr
falx cerebri
Surface layer of cerebrum
Cortex
Cerebral cortex is thrown into
Folds (gyri)
Folds (gyri) is separated by
fissures or sulci
Large sulci subdivide the surface of each hemisphere into
Lobes
Central core of white matter containing large mass of gray matter
Basal nuclei or ganglia
Fan-shaped collection of n. fibers
corona radiata
The corona radiata converges on the basal nuclei and passes on them as the
internal capsule
White matter to and from the cerebral cortex to the brainstem
Corona Radiata
Tailed nucleus situated on the medial side of internal capsule
Caudate nucleus
Lens-shaped nucleus on the lateral side of the internal capsule
Lentiform nucleus
Cerebral hemisphere cavity
lateral ventricle
Lateral ventricle communicate with the third ventricle through the
interventricular foramina
The cranial and spinal nerves are made up of
bundles of nerve fibers supported by connective tissue.
Pairs of CN
12
12 pairs of cranlal nerves leave the — and pass through — in the skull.
Brain, foramina
31 pairs of spinal nerves leave the — and pass through — In the vertebral column.
Spinal cord, intervertebral foramina
The spinal nerves are associated with regions of the spinal cord:
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coceygeal.
Each spinal nerve Is connected to the spinal cord by two roots:
anterior root and the polterlor root
— consists of bundles of nerve fibers carrying nerve Impulses away from the CNS-
Anterior root , efferent
Efferent /motor fibers’ origin lie in
anterior gray horn of the spinal cord.
The posterior root consists of bundles of
afferent fibers that carry nervous impulses to the CNS
Aka afferent fibers
Sensory fibers
cell bodies of these sensory fibers are situated ln a swelling on the posterior root
posterior root ganglion.
compared with that of the spinal cord, the length of the roots Increases progressively from __
above downward
upper cervical region, the spinal nerve roots are
short and run almost horizontally,
lumbar and sacral nerves below the level of the termination of the cord form
vertical leash of nerves around the ftlum termlnale
Bundle of lower nerve roots are called
cauda equlna.
After emerging from the intervertebral foranten, each spinal nerve Immediately divides Into a
large anterior ramus and a smaller posterior ramus
The posterior ramus
passes
posteriorly around the vertebral column to supply the muscles and skJn of the back
anterior ramus continues
anteriorly to supply the muscles and skin over the anterolateral body wall and all the mus- cles and skin of the limbs.
Ganglia can be divided into
sensory ganglia of spinal nerves (posterior root ganglia) and cranial nerves and autonomic ganglia.
fusiform swellings on the posterior root of each spinal nerve just proximal to the root’s junction with a corresponding anterior root
Sensory Ganglia/posterior root ganglia
Similar ganglia found along the course of cranial nerves
V, VII, VIII, IX, and X
Shape of ANS ganglia
irregular in shape
Autonomic ganglia is situated along the
course of efferent nerve fibers of the ANS.
AN Ganglia are found in
paravertebral sympathetic chains around the roots of the great visceral arteries in the abdomen and close to, or embedded within, the walls of various viscera
bundles of CNS axons that share a common
origin and destination
Tracts
several tracts that form an anatomically
distinct mass
Column
Centers and tracts that connect the brain with other organs and systems in the body
Pathway
Transmit information in the form of
electrical current at their cell
membranes from one area to
another
Neurons
Provide physical support for
neurons
▪ Represent 90% of cells in brain
Neuroglia
the functional unit of the nervous
system
Neuron
receive information from another cell or
receptor and transmit the message to the cell body
Dendrites
Dura mater
Pachymeninx:
arachnoid and pia mater
Leptomenix
separates the frontal and
parietal lobes
Central sulcus of Rolando
separates the temporal lobe
from the frontal and parietal lobes
Lateral Sylvian fissure
Controls somatic motor activities at the subconscious
level
Hypothalamus
Controls autonomic function
Hypothalamus
Coordinates activities of the endocrine and nervous systems
Hypothalamus
Secretes hormones
Hypothalamus
Produces emotions and behavioral drives
Hypothalamus
Regulates body temperature
Hypothalamus
Coordinates circadian cycles of activity (sleep-wake pattern)
Hypothalamus
Final relay point for ascending sensory information
Thalamus
Coordinates the activities of the cerebral cortex, basal nuclei, and cerebellum
Thalamus
Serves as a conduit for the ascending and descending
tracts connecting the spinal cord to the higher centers
in the forebrain
THE BRAINSTEM
Contains important reflex centers associated with
control of respiration and the cardiovascular system
THE BRAINSTEM
Contains important nuclei of cranial nerves III through
XII
Brainstem
Adjusts postural muscles and tunes on-going
movements
CEREBELLUM
