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Flashcards in Basic Neuro Structure+Functions Deck (18):

The Three Major Parts of the Brain

1) Cerebrum: largest part, on top.
2) Brain Stem: connects brain and spinal cord
3) Cerebellum: coordinates movement


Components of the Brain Stem

1) Midbrain: contains Substantia Nigra and VTA
2) Pons: Cranial Nerves V-VIII
3) Medulla: Autonomous control of cardiac, respiratory, vomiting, and vasomotor functions


Lower Motor Neurons: Anatomy

- Efferent nerves of PNS
- Soma located inside spinal cord
- Synapse on skeletal muscle (one LMN and all synapsed muscles="motor unit")
- Where it meets muscle=NMJ


Lower Motor Neuron Signs

1) Atrophy (decreased bulk)
2) Fasciculation (involuntary twitches)
3) Hypotonia (decreased muscle tone)
4) Hyporeflexia (decreased muscle stretch reflex)


Muscle Stretch Reflex

1) stretch receptors sends signal to cell body outside CNS
2) Efferent nerves synapse in spinal cord on afferent nerves that resist the stretch in primary muscle and inhibit antagonist muscles
- Ipsilaterally contained (same side)


White vs. Grey Matter

White Matter: most of the neuron's soma
- Forms cortex of brain (cerebral and cerebellar)
- within brain, forms Nuclei
- forms H-shape in SC
Grey Matter: myelinated axons


Upper Motor Neurons: Function, Location, Divisions

-Control LMNs and their activity
-Somas found in cerebral cortex, synapse onto LMNs
-Divided into: 1) Corticospinal Tract and 2) Corticobulbar Tract


Corticospinal Tract & Lesions

- synapse in SC, and cross over in the bottom of the Medulla
- Lesion in cortex -> contralateral weakness
- Lesion in SC -> ipsilateral weakness


Corticobulbar Tract & Lesions

- Synapses in brainstem
-Controls face and neck muscles
- upper face is bilateral, lower face is contralateral
-Varied patterns of weakness


Upper Motor Neuron Signs

1) Hyperreflexia
2) Clonus (rhythmic contraction of antagonist muscles)
3) Hypertonia
4) Extensor Plantar Response (vs flexor)
-scraping bottom of foot -> toes extend instead of flexing (Babinski's Sign)


Somatosensory Tracts and Crossing Over

1) Pain 2) Temperature 3) Gross Touch
-crosses over where it enters
-facially, goes down and crosses in the brainstem before going back up

4) Position 5) Vibration 6) Fine Touch
-crosses over in the brainstem
-facially, crosses over in brainstem as well


Cerebellum: Functions

Coordinates movement
1) Motor Planning: muscle contraction (which ones, intensity, duration)
-input: cortex

2) Position Sense: receptors send information to cerebellum to ensure action matches the plan

3) Feedback: to the part of the cerebrum that plans motor function


Brainstem: Function

- Connects cerebrum to the spinal cord and the cerebellum to the CNS
-also connects most of the cranial nerves
- Contains the Reticular Formation (circulation, respiration, digestion)
- Contains axons of the Long Tracts


Subcortical Cerebrum: Composition and Major Nuclei

- Made of white matter and deep nuclei
1) Internal Capsule (contains corticospinal tract with UMNs)
2) Corpus Callosum
3) Basal Ganglia (motor functions, cognition, emotion)
4) Thalamus (sensory function)
5) Hypothalamus (controls pituitary gland for endocrine system)


Cerebral Cortex: Structure and Lobes

- Folded, with large ridges (Gyri), small grooves (Sulci), and large folds (Fissures)

1) Frontal Lobe: contralateral motor cortex
-decision making, problem solving, planning

2) Parietal Lobe: contralateral processing of somatosensory information

3) Temporal Lobe: memory, emotion, hearing, language

4) Occipital Lobe: collaterally processes visual information


Cerebral Cortex: Primary vs Association Cortex

1) Primary: performs basic motor and sensory functions

2) Association: input of different types of information for more complex processing


CNS Neurotransmitters

1) Glutamate: most common excitatory NT
2) GABA: most common inhibitory NT in brain
3) Glycine: most common inhibitory NT in spinal cord
4) Acetylcholine
5) Histamine
6) Norepinephrine
7) Serotonin (produced and secreted in brain via Raphe Nuclei)
8) Dopamine


Organizational Differences between the Sympathetic and Parasympathetic Nervous System

1) Sympathetic: (starts in middle of spinal cord) small neuron projects to peripheral nervous system ganglia near spinal cord
-*sympathetic chain* set of neurons that project to the same ganglia in the middle portion of the spinal cord
2) Parasympathetic: (stars in brain stem of bottom of SC) long neurons project to ganglia near target cell
-shorter neurons from ganglia project to target cell