swallowing disorders
TRANSCRIPT
Neuroanatomy
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Neuron Basics
A. Cell Body
B. Dendrites
C. Axons
D. Synapses
E. Myelin
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Neurophysiology of Speech
Central Nervous System1. Brain
2. Spinal Cord
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Neurophysiology of Speech
A. Central Nervous System
1. Brain
2. Spinal Cord3. Neuronal Types
a) Tracts or Pathways
1) Commissural
2) Association
3) Projection Fiber Tracts
(a) Sensory
(b) Upper Motor Neurons5
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Peripheral Nervous System
– 1. Sensory Nerves– 2. Skeletal Nervous system
• a) Lower Motor Neurons• 1) Cranial Nerves• 2) Spinal Nerves
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Deep Structures
1. Basal Gangliaa) Striatum: Caudate Nucleus & Putamen
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Caudate
Nucleus
Putamen
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Deep Structures
1. Basal Gangliaa) Striatum: Caudate Nucleus & Putamen (receptive)b) Lenticular Nucleus: Putamen & Globus Pallidus (efferent/expressive)
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Putamen
Globus
Pallidus
Lateral
Ventricles
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Deep Structures
1. Basal Gangliaa) Striatum: Caudate Nucleus & Putamenb) Lenticular Nucleus: Putamen & Globus Pallidus
2. Thalamus
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Thalamus
Lateral
Ventricles
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Deep Structures
1. Basal Gangliaa) Striatum: Caudate Nucleus & Putamenb) Lenticular Nucleus: Putamen & Globus Pallidus
2. Thalamus3. Hypothalamus
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Lateral
Ventricles
Thalamus
Hypo-
Thalamus
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Hypo-
thalamus
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Brainstem
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BrainstemMidbrain
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Brainstem
1. Midbrain
2. Pons
3. Medulla
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Medulla
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Cerebellum
Cerebellum
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Spinal Cord
8 Cervical Nerves
12 Thoracic Nerves
5 Lumbar Nerves
5 Saccral Nerves
Dorsal and Ventral Roots
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Vascular System
internal carotid
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Vascular System
1. internal carotid2. anterior, middle, posterior cerebral
arteries
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Vascular System
1. internal carotid2. anterior, medial, posterior cerebral arteries3. anterior and posterior communicating arteries
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Vascular System
1. internal carotid2. anterior, medial, posterior cerebral arteries3. anterior and posterior communicating arteries4. circle of Willis
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Vascular System
1. internal carotid2. anterior, medial, posterior cerebral arteries3. anterior and posterior communicating arteries4. circle of Willis5. basilar artery
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H. Vascular System 1. internal carotid2. anterior, medial (middle), posterior cerebral arteries3. anterior and posterior communicating
arteries4. circle of Willis5. basilar artery6. cerebellar Arteries
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Corticospinal Tract
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More Corticospinal
• Lesions produce weakness
• Contralateral or ipsilateral, depending on site
• Generally, respiration our main concern here
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Corticobulbar Tract
• Lesions produce weakness, loss of skilled movements, decreased strength
• For our purposes, cranial nerves (Axons have direct connections to nuclei for CN V, VII, IX, X, XI, XII )
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Corticoreticular Tract
• Integrates and controls postural and general gross movements
• Influences reflex activity & muscle tone
• Regulates sensory transmission
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Basal Ganglia
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Basal Ganglia
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Basal Ganglia
•The basal ganglia play a complex and integral role in the control of movement:
•Selecting and maintaining purposeful motor activity while suppressing unwanted movement. •Monitoring/coordinating slow, sustained contractions related to posture and support. •Inhibiting muscle tone throughout the body (muscle tone is normally maintained through a balance of excitatory and inhibitory inputs to the neurons that innervate skeletal muscle).
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Basal Ganglia Circuit
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Cerebellar Circuits
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Cerebellar Circuits
A. Head and body position at rest
• Vestibular afferents provide inputs to the vestibular nuclei and to the vestibulocerebellum concerning body and head position (pathway 1).
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Cerebellar Circuits
B. Monitoring muscle tension and spinal cord activity • The dorsal spinocerebellar & cuneocerebellar tracts relay muscle tension activity. • The ventral and rostral spinocerebellar tracts provide information concerning spinal cord activity as it is affected by descending pathways and peripheral afferents. • These pathways project to the spinocerebellum, which then may send this information to the cerebral cortex via superior cerebellar peduncle projections to the ventral lateral thalamus (pathway 2).
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Cerebellar Circuits
C. Planning movements
• Corticopontine projections (pathway 3) provide the spinocerebellum and pontocerebellum via pontocerebellar connections with feed-forward information about an intended movement. This plan can then be “evaluated” in relation to current activity and corrections “formulated” and relayed back to motor cortex via the thalamus (pathway 2).
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Cerebellar Circuits
D. Plan execution
• For example, this may take place via corticospinal projections (pathway 4).
E. Monitoring of movement
• As the movement evolves, feedback information concerning changes in muscle spindle activity, as well as spinal cord activity, is relayed via the spinocerebellar tracts.
• This information is then sent to the deep cerebellar nuclei (pathway 5) for relay out of the cerebellum.
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Cerebellar Circuits
F. Movement correction
• Feedback as a result of monitoring may lead to adjustments and corrections of movement via cerebellonibral and cerebellothalamic connections (pathway 6).
• Feedback to the red nucleus, via the superior cerebellar peduncle, provides the basis for adjustments of flexor muscle tone.
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Cerebellar Circuits
G. Vestibular adjustments • Movement leads to changes in body and head position, causing vestibular afferents to the vestibular nuclei to induce adjustments of extensor muscle tone via vestibulospinal tracts (pathway 7). • Similarly, vestibular inputs may induce compensatory eye movements (i.e., vestibuloocular reflexes) via the ascending medial longitudinal fasciculus (pathway 8).
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Cerebellar Circuits
H. Learning of motor skills
• Has also been associated with the cerebellum.
• Repetition and skill acquisition leads to modulation of the complex spike activity of climbing fibers, and this in turn influences the simple spike activity of mossy fibers.
• The interaction between climbing and mossy fiber activity is likely to contribute to the necessary adaptation that changing circumstances require of even well learned motor skills.
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