1. Pneumotaxic Center 2. Nuclei of the Reticular Formation 3. Pontine Reticular and Vestibular Nuclei for motor control. 4. Swallowing Center (along with the Medulla Oblongata).

CNS Part 2 Flashcards by sophie rosen

midbrain contains (3)

centers for motor control
nuclei of the reticular formation
periqueductal gray region (PAG)

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Midbrain:

Centers for motor control (3)

A. Substantia Nigra
B. Red Nucleus
C. Superior and Inferior Colliculi

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The --- --- rises 
from the superior and inferior 
colliculi of the midbrain. It 
causes head turning in 
response to sudden visual or 
auditory stimuli.

tectospinal tract

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“Morphine and endogenous opioid peptides also act in the midbrain Periaqueductal Gray (PAG) to induce

analgesia

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The PAG is a part of a descending pathway that modulates

pain transmission by inhibition of

primary afferent transmission in the dorsal horn

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These
PAG neurons activate neurons in the (2) that project to the spinal cord where they release serotonin and norepinephrine,
respectively, to inhibit the activity of dorsal horn neurons that receive input from nociceptive
afferent fibers

Nucleus Raphe Magnus and Rostral Ventromedial

Medulla

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Pons (4)

Pneumotaxic Center
Nuclei of the Reticular Formation
Pontine Reticular and Vestibular Nuclei for motor control.
Swallowing Center (along with the Medulla Oblongata).

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Pneumotaxic Center regulates centers in the —. Activation limits
— — and increases — —

Medulla
inspiration time
respiration rate

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Cerebellum is Involved in (3)

motor control of
posture, muscle tone and
learning of repeated motor
functions

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Diseases of the cerebellum result in (3)

alterations in gait, balance
and coordination of motor
activities; not paralysis.

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the most inferior portion of brainstem

and is continuous with the spinal cord

medulla oblongata

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medulla oblongata includes (5)

1. Autonomic control centers 
(Cardiovascular, Respiratory, 
Swallowing, Vomiting, etc.)
2.  Nucleus Raphe Magnus (Serotonin) 
and Rostral Ventromedial Medulla 
(Norephinephrine) that release NT 
onto dorsal horn neurons to reduce 
ascending pain signals.
3. Medullary Reticular Nuclei (motor)
4. Pyramids (motor axons of the 
Corticospinal Tract)
5. Nuclei for the Reticular Formation

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Nerve signals in the brainstem activate the cerebrum by activating

Neurohormonal Systems

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Neurohormonal Systems release specific

facilitatory or inhibitory

substances into selected areas of the brain

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Reticular excitatory activating
system (RAS) in the brainstem
activates the cortex via the

thalamus
– Pain signals increase the activity of the
excitatory area.
– ACH is one of the NT

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Consciousness is maintained by the normal
functioning of the — above the mid pons and its
bilateral projections to the thalamus and cerebral
hemispheres.

RAS

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Reticular inhibitory system

inhibits the activity of the

reticular
excitatory area.
– Serotonin is one of the NT for this system.

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Coma results from lesions that affect either the

RAS or both cerebral hemispheres.

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Barbiturates (ex. Thiopental) depress the RAS in

the brainstem, which controls

consciousness

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— is involved in cognitive

functions, especially memory

Acetylcholine

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— — accounts for
the majority of dementia cases. Its
incidence increases with age

Alzheimer’s Disease

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Alzheimers is due to

neuronal accumulation of
abnormal proteins (A-Beta Amyloid
and tau -a microtubule associated
protein) and Neurofibrillary Tangles.

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Areas most severely impacted by AD are

the (2)

hippocampus and temporal lobes.

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AD causes degeneration of cholinergic
neurons in the — that project throughout the
cortex.

Nucleus Basalis of Meynert

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Treatment for Alzheimer’s Disease | includes

Acetylcholinesterase Inhibitors and NMDA (Glutamate receptor) antagonist.

skipped | Serotonin influences a multitude of functions, including (10)

sleep, cognition, sensory perception, motor activity, temperature regulation, nociception, mood, appetite, sexual behavior, and hormone secretion

It has been hypothesized that every neuron in the brain may be in synaptic contact with a

serotonin neuron

--- --- are located in the | Midbrain, pons, and medulla

``` Raphe nuclei (ex. Nucleus Raphe Dorsalis), Pons (ex. Nucleus Raphe Pontis) and Medulla Oblongata (ex. Nucleus Raphe Magnus). ```

Nucleus Raphe Magnus is | involved in

dampening ascending pain (nociceptive) signals

The physiological processes under | dopaminergic control include (5)

``` reward, emotion, cognition, memory, and motor activity. ```

Neurons in the Substantia Nigra Compacta project to the Basal Nuclei; this is the pathway that degenerates in

Parkinson’s Disease

Neurons in the -- ---- --- project to the Nucleus Accumbens and the Prefrontal Cortex

Ventral | Tegmental Area

``` Neurons in the Ventral Tegmental Area project to the Nucleus Accumbens and the Prefrontal Cortex. Dysfunction in this pathway is associated with (4) ```

``` addiction, schizophrenia and psychoses (bipolar depression) and learning deficits. ```

Norepinephrine impacts all areas of the brain and facilitates excitatory synaptic transmission leading to (2)

attention and arousal

``` “The monoamine hypothesis of depression suggests that depression is related to a deficiency in the amount or function of cortical and limbic (3) ```

serotonin (5-HT), norepinephrine | (NE), and dopamine (DA). “

``` All classes of antidepressants appear to enhance the synaptic availability of (3) ```

5-HT, | norepinephrine, or dopamine

Most voluntary movements ‘initiated’ by the cerebral cortex are achieved when the cortex activates ‘patterns’ of

function stored in lower brain areas – the brainstem, basal ganglia and cerebellum.

The motor system learns by doing and performance improves with repetition. Involves

Long-Term | Potentiation

Pyramidal/Direct | Pathway

``` UMNs from the cerebral cortex initiate and direct sequences of voluntary movement ```

Extrapyramidal/ Indirect Pathways

``` UMNs originate in motor centers in the brainstem and direct subconscious muscle tone, posture, balance and orientation of the head and body ```

``` Damage to UMN causes --- --- on muscles on the --- side of the body. This results in (3) ```

``` spastic paralysis opposite increased muscle tone, exaggeration of reflexes and pathological reflexes such as the Babinski Reflex ```

``` Damage to the LMN causes --- --- of muscles on the --- side of the body. There is neither voluntary nor reflex action of the muscle fibers and tone is decreased ```

flaccid paralysis | same

The LMN is cholinergic and releases -- that binds to nicotinic receptors on skeletal muscle.

ACH

The motor cortex has three regions:

(1) Premotor Area/Cortex (2) Supplementary Motor Area/Cortex (3) Primary Motor Area/Cortex

The --- --- sets posture (ex. position shoulder and arm) at the start of planned movement .

Premotor cortex

The Premotor area | determines the overall

motor plan

The --- --- --- activates | specific muscles to execute the plan

Primary motor cortex (UMN)

More than half of the Primary Motor Cortex is devoted to | controlling the muscle of the (2)

hands and muscles of speech

The --- --- --- is involved in organizing or planning motor sequences

supplementary motor cortex

The supplementary motor cortex is involved in organizing or planning motor sequences. Lesions of this area produce (2)

awkwardness in performing complex activities | and difficulty with bimanual coordination

Axons from neurons in the Supplementary and Primary Motor | Cortex make up the

Corticospinal (Lateral and Ventral) and

Corticospinal (Pyramidal) Tract | • Called the

Direct Motor Pathway

Corticospinal (Pyramidal) Tract | • Fibers originate in the --- --- and the fibers descend through the

Motor Cortex | internal capsule of the cerebrum

Corticospinal (Pyramidal) Tract • In the Medulla Oblongata, these axons form bundles known as the

pyramids

90% of the axons decussate to the contralateral side in | the medulla oblongata. These axons form the

Lateral Corticospinal Tract of the spinal cord. • DISTAL MUSCLES

The 10% that do not decussate in the medulla and | these axons from the

Anterior Corticospinal Tract. These fibers decussate in the spinal cord before synapsing with the LMN. • PROXIMAL MUSCLES

Both synapse with the LMN in the

Dorsal Horn | of the spinal cord

Corticobulbar Tract • Fibers originate in the --- --- and terminate on

motor cortex | nuclei in the brainstem

Corticobulbar Tract • The following cranial nerves receive input from the corticobulbar tract:

``` – Oculomotor (CN III), Trochlear (CN IV), Trigeminal (CN V), Abducens (CN VI), Facial (CN VII), Glossopharyngeal (IX), Accessory (CN XI), Vagus (X), Hypoglossal (CN XII) ```

Corticobulbar Tract | • Innervate LMN that control

conscious control over skeletal muscles that move the eye, jaw, face and some muscles of the neck and pharynx.