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Central Nervous System (CNS) = made up of the brain and spinal cord,…
Central Nervous System (CNS)
= made up of the brain and spinal cord, sensory input is sent to CNS and motor output is sent from the CNS
Anatomical Organization and Composition of
Brain
gyrus = raised parts of cerebrum, "hills"
sulcus = grooves between gyrus of cerebrum, "valleys"
fissure = a division, deeper than sulcus, divides lobes of brain
Ventricles of brain
2 lateral ventricles located on each side of cerebral cortex
third ventricle in lower brain near diencephalon
fourth ventricle runs along brain stem and continues into central canal of spinal cord
2 lateral apertures, 1 medial apertures
Blood-brain barrier
: simple squamous epithelium (blood vessels and capillaries), cells connected together by
tight junctions
(special connections that serve as a barrier and prevent molecules from passing between)
Major portions of the brain
Cerebrum
Frontal lobe
: initiates voluntary movement,
prefrontal cortex
(gray matter, where processing occurs, planning, decision-making, task management, problem-solving, some memory
Broca's area
= speech production/talking, located on left side of brain
Parietal lobe
: processes sensory stimuli
Wernicke's area
= recognizes/understands speech, located only on left side of brain, partly on parietal and partly on temporal
Temporal lobe
:
auditory and olfactory cortex,
recognition of objects, written words, faces, emotional response (limbic system), memory
Occipital lobe
:
visual cortex
Insula
: deeper lobe within lateral sulcus,
gustatory cortex
(taste),
general visceral sensations
processed (hunger, thirst, etc)
Diencephalon
Thalamus
can amplify or dampen signals
relay station for all conscious sensory signals traveling to cerebral cortex (except olfactory)
Hypothalamus
control/regulation of
autonomic or visceral motor system
, body temp, sleep/wake cycles, endocrine system, etc, emotion and memory
Epithalamus
pineal gland
- produces hormone melatonin (prepares for sleep)
Brainstem
- connector between CNS and PNS, most sensory information goes through brainstem
Midbrain
cerebral peduncles
= motor tracts that connect midbrain to cerebral cortex
corpora quadrigemina
(4 bumps)
superior colliculi
(visual reflexes, subconscious tracking/following)
inferior colliculi
( auditory reflexes, "fight or flight" response
Pons
Pyramidal
tracts
= motor tracts, run through entire brainstem
Reticular formation nuclei
= gray matter in pons, control of autonomic behavior (vital functions), cardiovascular center, vascular center, respiratory center
Medulla oblongata
(collection of gray matter)
pyramids
= nerves pyramidal in shape
decussation of pyramids
= "crossing over" of pyramidal tracts
cranial nerve nuclei
= where cranial nerves connect with brainstem
sensory tracts
= input from sensory neurons to thalamus to cerebral cortex
cerebellum
= smooths and coordinates body movement, maintain posture and equilibrium (receives messages from proprioceptors)
cerebellar peduncles
superior
- connects cerebellum to midbrain
middle
- connects cerebellum to pons
inferior
- primarily carries proprioceptive signals to cerebellum
3 major cerebral regions
Cortex
= gray matter, located along superficial surface, has neuron cell bodies that are NOT myelinated, "cities" (where processing occurs
White matter
= myelinated and unmyelinated neurons, where signals travel, "highways" (no processing)
Association tracts
- connects parts of same hemisphere
Commissural tracts
- connects one hemisphere to another,
largest
of these tracts is corpus callosum
Projection tracts
- run vertically,
longest
, run from cerebrum through thalamus, through brain stem and into spinal cord
signals are both
ascending
(sensory) and
descending
(motor) tracts
Cerebral (basal) nuclei
= deep gray matter, anything NOT myelinated, area of processing and integration
Precentral Gyrus
initiating voluntary movement (motor, efferent, away from CNS)
controls feet, legs, thigh, hands, head
facial expressions, tongue movement
primary motor cortex
= main area of brain invlolved in motor function, located on frontal lobe, directly anterior to central sulcus
Postcentral Gyrus
recieving signals (sensory, afferent, towards CNS)
primary somatosensory cortex
= mian area of brain involved in sensory function located on parietal lobe, directly posterior to central sulcus
signals going TO this area from skin, general senses, genitals
control of all skin receptors, head, arms, hands, genitals, mouth, throat
Anatomical Organization & Components of
Spinal Cord
Gross anatomy
Cervical and lumbar enlargements
= areas where more axons are present from the upper and lower extremities
Conus medullaris
= located on L1 or L2 vertebrae, where spinal cord tapers and gets thinner
Cauda equina
= looks "horse's tail", nerves/nerve roots leaving the spinal cord
Filum terminale
= connects spinal cord to coccyx, stabilizes/anchors it
Location, Composition, Function of Roots (refer to color-coated image in notes)
Anterior root (ventral root)
= made up of multipolar neurons (output)
Lateral horn
= where
visceral motor
is, output leaves the spinal cord through the anterior root
Ventral horn
= where
somatic motor
is, output leaves the spinal cord through the anterior root
Posterior root (dorsal root)
= unipolar neurons in ganglion (input)
dorsal horn
= where
visceral sensory and somatic sensory
are, input go into the spinal cord through the dorsal root
Posterior root ganglion (dorsal root ganglion)
= sensory neurons
Tracts
Ascending tracts
=
sensory
signal traveling
toward
the brain
Descending tracts
= signals traveling
away
from the brain, major
motor
tracts (movement signals)
Meninges & Cerebrospinal Fluid (CSF)
dura mater
= "tough mother"
periosteal
dura mater = next to bone (superficial)
meningeal
dura mater = deep to periosteal layer
subdural space
= under menigeal dura mater, very little fluid
dura mater continues from brain around spinal cord, but only 1 layer (meningeal) around spinal cord
arachnoid mater
= "spider mother", looks like web, thin/transparent layer deep to subdural space
blood vessels running through it
where CSF is located
, besides in ventricles of brain and central canal of spinal cord
pia mater
= "gentle mother", thin layer that covers cortex, vascular layer w/ small blood vessels
epidural space
= superficial to dura mater, adipose tissue located here
CSF functions
: bouyancy for brain and spinal cord, cushions/protects head from jolts/impact, nourishes brain
arachnoid granulations
= villus-like locationsin the arachnoid mater of brain where CSF is pushed out into the dural sinus
choroid plexus
= where CSF is made, a network of capillaries and ependymal cells (glial cells)
ependymal cells
= take in and modify fluid
Dural venous sinuses
= formed by periosteal and meningeal dura mater (where they split apart)
dural and coronary sinuses = vessels (oxygen poor blood)
no smooth muscle in sinus walls
where veins empty oxygen poor blood