Download CNS lecture

CENTRAL NERVOUS SYSTEM ANATOMY *blue is for honors
I: Protection: Skull, Meninges and CSF: see p82 color book:
choroid plexsus: specialized capillary network projecting from the pia mater into the ventricles of the
brain forming cerebral spinal fluid (70% of CSF) 99% water, (glucose, aa, salt, less density and protein
than plasma)
~ 150 mL CSF in ventricles and subarachnoid space
 Dura mater, arachnoid , pia mater
 CSF Circulation: lateral > interventricular foramen > 3rd > cerebral aqueduct > 4th
 Superior sagital sinus and arachnoid villi
 Capillaries are different: tight junctions combine ET cells
II. BRAINSTEM: medulla, pons and midbrain
Medulla oblongata w/ pyramidal tracts, houses cranial nerves: vestibulocochlear,, hypoglossal,
glossopharyngeal, vagus, accessory and *penumotaxic center, * CV & Vasomotor center VITAL CENTERS
top of the spine, two bulges of white matter = pyramids (pyramid tracts)
 Anterior/ventral surface: major voluntary motor pathways from cerebrum and decussation
 Posterior/dorsal surface: 2 pairs of ascending tracts
1. fasciculi gracilis
2. fasciculi cuneatus : touch , body pressure and position
 All ascending sensory and descending motor tracts
 VITAL CENTERS (CV and Vasomotor center)
o Cardiovascular center (rate/force of heart) diameter = vasodilation
o Respiratory center: adjust basic rhythm of breathing
o Reflex: vomit, cough, sneeze, swallow
o Reticular formation: gray matter from spine to thalamus
o Keeps cerebrum conscious and alert
o Reflex centers: cardiac, vomit, sneeze, vasomotor, cough, respiratory, swallow
o 12 pairs of cranial nerves
Pons w/ Reticular formation is a relay pathway between the motor cortex and the cerebellum also
functions as a *pneumotaxic center *houses cranial nerves: trigeminal, abducens, and facial.
 Respiration center
 Reflex w cranial nerves 5-8, eye, chewing, facial expression, taste, equilibrium
 RF and cranial nerve origin
Midbrain w/ cerebral peduncles
 corpora quadrigemina: Righting reflexes
o Superior colliculi: visual reflex center
o Inferior colliculi: auditory reflex center
 Cranial nerve origin: cranial nerves oculomotor and trochlear
 Cerebral peduncles: crus cerebri: descending tracts
 Substantia nigra: pigmented neurons in motor fxn and produces the precursor for the
neurotransmitter DOPAMINE
 RF: ascending paths
 Red nuclei (pink)important for acting as a relay between motor cortex and muscles of the
limbs for limb flexion; cranial nerves 3 and 4 with the eye
 Roof Midbrain: muscle tone and posture
III. CEREBELLUM
 Arbor vitae: coordination of skeletal muscle movements
 Some cognitive function in predicting motor movements
 Fine coordination: 3 main function
o Smooth not jerky, steady not trembling
o Muscle tone and posture
o Flocculonodular lobe= equilibrium and posture
 Hemispheres separated by falx cerebelli
 Cereballar cortex – gray
 But mainly white matter underneath : arbor vitae
 30 million purkinje cells in cerebellar cortex
 integrate infor motor activity to keep informed about body position
 axons carry infor to nuclei for relay to brainstem
IV. DIENCEPHALON
Thalamus: all sensory except smell to the cerebrum
 expresses emotions with hypothalamus
 cognition: awareness and acquisition of knowledge
Hypothalamus w/ VITAL CENTERS: maintain and regulate HOMEOSTASIS
 sleep and wake patterns
 controls Endocrine system; link the endocrine and nervous systems
 secretes variety of hormones that regulate pituitary
 secretes oxytocin and antidiuretic hormone
 osmotic balance (thirst)
 thermoregulation
 appetite
 sexual behavior and emotional aspect of sensory
Pituitary gland: master gland of the body secretes: posterior lobe: secretes oxytocin and antidiuretic
hormone; anterior lobe: ACTH affects adrenal cortex; TSH affect thyroid and thyroxin; FSH,LH
affects ovary and testes; Prolactin affects mammary glands; GH for bone growth;
Mammillary bodies:
 activate feeding reflexes such as swallowing and licking the lips and may be involved in
relaying olfactory messages
Epithalamus
 pineal gland: produces melatonin for biological clock
choroid plexsus: specialized capillary network projecting from the pia mater into the ventricles of the
brain forming cerebral spinal fluid
Reticular Formation: groups of neurons clustered in the spinal cord through the medulla, pons and
midbrain. Have axons that reach into the diencephalon (specifically the hypothalamus, thalamus and
cerebellum ) Form the RAS*
RAS *(reticular activating system): nuclei axons connect hypothalamus, thalamus, cerebellum and spinal
cord to send sensory information to keep the cortex alert and conscious ALSO acts as a filter for
sensory input to the cortex…filters out 99% of sensory input as unimportant. Has to be inhibited in
order to sleep
VA. CEREBRUM12 billion nerves and 50 billion glial cells
Cortex
Fissures longitudinal fissure (flax cerebri)
Gyri
Sulci
Hemispheres
lobes: frontal, parietal, occipital, temporal, central and limbic
neocortex: new mostly only in mammals
Ventricles/CSF
Cerebral white matter:
1. association (within hemispheres)
2. commissure –connects neoccortex of hemispheres (corpus callosum)
3. projection
Grey Matter: cell bodies of neurons involved inhemispheres function: CEREBRAL CORTEX
Cortex: 90% is neocortex only in mammals
Basal Nuclei: grey matter deep within white matter surrounding 3rd ventricle they influence: monitoring,
starting, stopping of stereotyped motor movement (voluntary)
 subconscious movement
 humans: planning, programming movement, information feedback with cortex,
 help decisions about sensory input
Amygdala nucleus: part of the limbic system located deep within each hemisphere/ important part of
emotional feelings linked to cognitive input (pleasure and fear emotions) Fear conditioning sends input to
hypothalamus to signal the sympathetic NS to act
Reticular Activating System: nuclei axons connect hypothalamus, thalamus, cerebellum and spinal
cord to keep the cortex alert and conscious. Also acts as a filter for sensory input to the cortex
… filters out 99% of sensory input as unimportant
o RAS: arousal system
o Complex polysynaptic path in brainstem and thalamus RF
o Receives messages from neurons on spine and other parts and communicates with cerebral
cortex with complex circuits
o Ultimately responsible for consciousness
o Extent of RAS activity determines state of alertness (focus)
o Slow stimulation get sleepy and bored
o Toss and turn at night due to RAS
o Effects the way we react to stimuli
o If damaged= deep permanent coma
o When RAS is stimulated the whole NS is stimulated for 30 sec
Function:
1. Sensory: interprets signals so we “know: what we are seeing, hearing, tasting, smelling …
2. Motor: responsible for all voluntary movement (somatic) / some involuntary (autonomic)
3. Association: all intellectual activities of cerebral cortex: learning, reasoning, memory storage,
recall, language abilities, even consciousness
VB. Lobes:
Frontal: primary motor area allows conscious movement of skeletal muscles, higher intellectual reasoning,
complex memory
Parietal lobe: somatic sensory area : impulses from sensory receptors are localized and interpreted; path
are X’d, able to interpret characteristics of objects feel with hand and to comprehend spoken and
written language
Occipital lobe: visual cortex, receives visual info via thalamus (primary visual area)integrates info to
formulate response (visual association area)
Temporal lobe: emotion, personality, memory behavior, auditory and olfactory area, complex memory
(both neo and old cortex)
Limbic Lobe: (linked with temporal) ring of cortex around cerebral ventricles, connections between
emotional and cognitive mechanism, emotional, autonomic, subconscious motor and sensory drives, sexual
behavior, biological rhythms
 Motivation=pleasure or punishment
 Limbic is the connection between emotional and cognitive mechanisms
Specialization areas: *see pg 435
primary motor in precentral gyrus,: motor cortex: control voluntary skeletal movment
primary sensory in postcentral gyrus *see Homunculi pg 436),: somatosensory area:: receives infro
from skin, joint via thalamus
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somatosensory association cortex
Primary somatosensory cortex,
Visual association area
Auditory association area
primary visual cortex
primary auditory cortex
auditory association area
olfactory cortex
gustatory cortex
Wernicke’s language area
primary somatic motor cortex: axons from the primary motor area in the frontal lobe form major
voluntary motor tract which descends into the cord, paths are crossed and body is represented upside
down. Most neurons are dedicated to fine motor control of face, moth and hands.
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premotor cortex
primary motor area
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Spatial Discrimination:
Speech area: junction of parietal and occipital and temporal lobes: allows us to understand words, make
connections between words, in one hemisphere
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Broca’s area: base of precentral gyrus (usually inleft hemisphere) ability to speak
Prefrontal
Cerebral dominance: (L) language abilities, mathematics, intellectual functions with language
(R) spatiotemporal matter, recognize face, appreciates and recognizes music
VC. DISORDERS:
Alzheimers disease
Parkinson’s disease
Stroke
Aphasia
Concussion
Contussion
Cerebral contusion
VI: Spinal Cord
Anatomy
VII: Disorders and Clinical Applications
Lumbar puncture
Spinal tap vs epidural
Spina Bifida
Anencaphaply
Paralysis
Spinal Shock
ALS
Poliomyelitis
VIII: Neurotransmitters and the effects of drugs on NS
Catecholamines
Nitric oxide
Indolamines
Carbon monoxide
Dopamine
cocaine
Norepinephrine
Serotonin
GABA
Endorphins
Enkaphalins