1/20: CNS Overview Flashcards
What is the nervous system organized into?
Central & peripheral NS
Somatic & autonomic NS
Afferent & efferent pathway
What plays a key role in both pathways?
The thalamaus (part of the diencephalon)
What is necessary for almost all cortical activity?
Thalamic excitation of the cerebral cortex
Sensory neurons enter the spinal cord via the _______
Dorsal root
What do sensory neurons synapse with after entering the spinal cord via the dorsal root?
Interneurons and/or motor neurons in the gray matter
Motor neurons exit the spinal cord via the __________ to go to _______
Ventral root; effectors
The spinal cord contains a central portion of _____ matter surrounded by _____ matter
Gray; white
What is gray matter?
Neuron cell bodies and interneurons
What is white matter?
Neuron axons
What contains ascending sensory axons?
Dorsal columns and spinothalamic tract
What contains descending motor axons?
Corticospinal tract
Is the dorsal columns sensory or motor?
Sensory
What does the dorsal column transmit and send to brain?
Vibration
Position
Two-point discrimination
Deep touch
Is the corticospinal tract motor or sensory?
Motor
What does the corticospinal tract transmit and send to motor neurons?
Paralysis, paresis
Spasticity
Hyper-reflexia
Clonus
Babinski sign
Is the spinothalamic tract sensory or motor?
Sensory
What does the spinothalamic tract transmit to brain?
Contralateral pain and temp
What is the cerebrum further divided into?
a. Cerebral cortex (cortical level)
b. Basal nuclei
What is the diancephalon further divided into?
a. Hypothalamus
b. Thalamus
What are the subcortical levels of the brain?
- cerebrum
- diencephalon
- midbrain
- pons
- medulla oblongata
- cerebellum
What is collectively called the brainstem?
Midbrain/mesencephalon
Pons
Medulla oblongota
The two cerebral hemispheres are further subdivided into what lobes?
Frontal
Parietal
Occipital
Temporal
What are specialized areas of the frontal lobe?
Premotor and primary motor cortex
Prefrontal cortex
Broca’s area
What are specialized areas of the parietal lobe?
Primary sensory cortex
Primary gustatory cortex
What are specialized areas of the temporal lobe?
Primary auditory cortex
Primary olfactory cortex
Wernicke’s area
For each sensory modality, there is a _______ area as well as a _______ area
primary area (primary olfactory cortex); modality-specific association area (olfactory association cortex)
What is the function of association (secondary) areas?
Receive and analyze signals from multiple regions of both the sensory and motor cortices and subcortical areas
In about 95% of people, the _____ hemisphere is the dominant/categorical hemisphere
Left
What does the left hemisphere contain?
Wernicke’s area and broca’s area
*motor areas controlling hands are also dominant leading to right-handedness in most people
What is the cerebral cortex?
Gray matter on the outer surface of the cerebrum
What does the cerebral cortex contain?
Neuron cell bodies
What does the corpus callosum allow for?
Information stored in one hemisphere available to the opposite hemisphere
What does severing the corpus callosum prevent?
Somatic and visual information from the right side of the body from reaching the general interpretive area to be used for decision making
What lobes of the cerebral cortex would you suspect to
be the site of the lesion if a person was demonstrating
the following impairments?
1. Paresthesias (numbness, abnormal sensations of tingling, electric shock, or
pins and needles) or an impaired ability to localize or measure the intensity of painful stimuli or impaired
perception of various forms of cutaneous sensation.
2. Visual hallucinations as flashes of light, rainbows, brilliant stars, or bright lines.
3. Buzzing and roaring sensations and/or
mild hearing loss.
4. Seizures that begin as focal twitching
and spread contralateral flaccid paresis, or paralysis
- Parietal
- Occipital
- Temporal
- Frontal
What does the prefrontal association area (cortex) do?
- Decreased aggressiveness and inappropriate
social responses - Ability to progress towards goals or to carry
through sequential thoughts - Keep track of many pieces of information
simultaneously and recall the information as
needed (working memory)
What do broca’s and wernicke’s areas do?
- In left cerebral hemisphere in almost all right-handed individuals.
- Language Centers involved in production of speech (Broca’s) and interpretation of spoken and written language (Wernicke’s)
What is the pathway of speaking a heard word?
- primary auditory area
- Wernicke’s area to interpret (comes first because involved w/ spoken and written language)
- Broca’s area
- Motor cortex to speak the word
What is the pathway of speaking a written word?
- Primary visual cortex in occipital lobe
- Wernickes to interpret
- Broca’s area (make plan for how to say it)
- Frontal lobe to end at motor cortex
What is broca’s area?
Production of speech
What is wernicke’s area?
Interpretation of speech
What is wernicke’s aphasia?
Fluent and receptive
- damage to wernicke’s area
- individual called fluent because can say words just don’t make sense
- trouble recepting or receiving info
What is basal nuclei considered?
An accessory motor system as it functions in close association with the cerebral cortex (frontal lobe) and the corticospinal descending motor pathway
What are basal nuclei associated with?
Cerebrum
Nuclei = neuron cell bodies
What do basal nuclei include?
Caudate nucleus, putamen. globus pallidus, subthalamic nucleus
What two pathways do the basal nuclei form?
Direct and indirect pathway
What does the direct pathway do?
Increases cortical excitation and promotes movement
What does the indirect pathway do?
inhibits cortical activity and inhibits movement
What is terminology for the stratum?
Stratum = caudate + putamen
What is terminology for the lentiform nucleus?
lentiform nucleus = globus pallidus + putament
What is terminology for the corpus striatum?
corpus striatum = lentiform nucleus + caudate
Disorders of the basal nuclei cause?
Movement disorders - dyskinesias
What are hypokinetic disorders (parkinson’s disease) due to?
Damage to the direct pathway
What are hyperkinetic movement disorders (huntington’s disease) a result from?
Damage to the indirect pathway
What does the diencephalon include?
- thalamus
- hypothalamus
- epithalamus
- subthalamus
What is the function of the thalamus?
Sensory relay for information for the cerebral cortex
What other kind of pathways synapse in the thalamus?
Motor control pathways
What is the hypothalamus involved in maintaining?
Homeostasis
What systems does the hypothalamus impact?
The autonomic, endocrine and limbic systems
What does the epithalamus contain?
The pineal body (secretes melatonin) that aids in the regulation of circadian rhythyms
What is the subthalamus involved in?
Basal nuclei and control of voluntary movement
What does damage to the subthalamus cause?
Hemiballismus (contralateral flinging movement of one or both extremities)
What is contained in the midbrain?
- centers for motor control
- nuclei of the reticular formation
- periaqueductal gray region (PAG)
What three things make up the center for motor control?
- Substantia nigra
- red nucleus
- superior and inferior colliculi
What are the functions of the superior colliculi?
Visual
What are the functions of the inferior colliculi?
Auditory
What rises from the superior and inferior colliculi of the midbrain?
Tectospinal tract
What does the tectospinal tract cause?
Head turning in response to sudden visual or auditory stimuli
*hearing someone drop something and turning head
What act in the midbrain periaqueductal gray (PAG) to induce analgesia?
Morphine and endogenous (built-in) opioid peptides
What is the periaqueductal gray (PAG) part of?
Descending pathway that modulates pain transmission by inhibition of primary afferent transmission in the dorsal horn
**Descending neurons that stop ascending signals
What is the pons known as?
The pneumotaxic center
What does the pons regulate?
Centers in the medulla
What does activation of the pons limit?
Inspiration time and increases respiration rate
Pons nuclei help the formation of what?
Reticular formation
What is in the pons that is for motor control?
Pontine reticular and vestibular nuclei
Pons is a ______ center
Swallowing (along with the medulla oblongata)
What is the cerebellum involved in?
Motor control of posture, muscle tone and learning of repeated motor functions
Diseases of the cerebellum result in?
Alterations in gait, balance and coordination of motor activities; not paralysis
What is the most inferior portion of the brainstem and is continuous with the spinal cord?
Medulla oblongata
What 5 things does the medulla oblongata include?
- Autonomic control centers
- Nucleus raphe magnus (serotonin) and rostral ventromedial medula (norepinephrine)
- Medullary reticular nuclei
- Pyramids
- Nuclei for the reticular formation
What do nucleus raphe magnus and rostral ventromedial medulla do?
Release NT onto dorsal horn neurons to reduce ascending pain signals
What are pyramids in the medulla oblongata?
Motor axons of the corticospinal tract that cross over on the other side of the body
How do nerve signals in the brainstem activate the cerebrum?
By activating neurohormonal systems that release specific facilitatory or inhibitory substances into selected areas of the brain
What in the brainstem activates the cortex via the thalamus?
Reticular excitatory activating system (RAS)
What does Reticular excitatory activating system (RAS) do?
- pain signals increase the activity of the excitatory area
- ach is one of the nt
What is consciousness maintained by?
The normal functioning of the RAS above the mid pons and its bilateral projections to the thalamus and cerebral hemispheres
What does a coma result from?
Lesions that affect either the RAS or both cerebral hemispheres
What depress the RAS?
Barbiturates (Ex: thiopental), which controls consciousness
