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BIO303: Neurobiology

Unit 9: Motor Systems   We will now focus on motor systems. Much of our motor control takes place through nerve-to-muscle signaling in the form of the neuromuscular junction. You will learn that fine motor control and movement modulation – though involuntary – require a great deal of nervous input and output. You will also learn about the autonomic nervous system, which controls many of our internal organs. This unit will encompass both aspects of voluntary and involuntary motor control, examining the systems and major mechanisms of movement.  

Unit 9 Time Advisory
This unit will take you 16.5 hours to complete.

☐    Subunit 9.1: 5 hours

☐    Subunit 9.2: 3.5 hours

☐    Subunit 9.3: 4 hours

☐    Subunit 9.4: 4 hours

Unit9 Learning Outcomes
Upon successful completion of this unit, the student will be able to:
- compare and contrast voluntary motor control, involuntary motor control, and the systems which regulate motor control; - explain lower motor neuron syndrome, upper motor neuron syndrome, and amyotrophic lateral sclerosis; - explain the significance of decussation to motor neuron control; - compare and contrast the tracts which control upper motor neuron control; - compare and contrast the brain regions and tracts which are responsible for movement modulation; and - define the parts of the visceral motor control system and the tracts and receptors responsible for visceral motor control.

9.1 Lower Motor Circuits   9.1.1 Lower Motor Neurons and Motor Neurons   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Functional Organization of the Primary Motor Cortex” and “The Motor Unit” Links: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Functional Organization of the Primary Motor Cortex” (HTML) and “The Motor Unit” (HTML)
 
Instructions: Click on the first link, and read the entire webpage for lower motor neurons. Then, click on the second link, and read the entire webpage to learn about α-motor Neurons.
 
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9.1.2 Local Circuit   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 17: Descending Control of Spinal Cord Circuitry: General Information” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 17: Descending Control of Spinal Cord Circuitry: General Information” (HTML)
 
Instructions: Read the webpage, and click on the hyperlinks to Figure 17.1. 
 
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9.1.3 Ventral Horn   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 17: Descending Control of Spinal Cord Circuitry: General Information” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 17: Descending Control of Spinal Cord Circuitry: General Information” (HTML)
 
Instructions: Read the entire webpage.
 
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9.1.4 Neuromuscular Junction   - Reading: The University of Texas’s Neuroscience Online: Dr. John Byrne’s “Ch 4: Synaptic Transmission and the Skeletal Neuromuscular Junction” Link: The University of Texas’s Neuroscience Online: Dr. John Byrne’s “Ch 4: Synaptic Transmission and the Skeletal Neuromuscular Junction” (HTML)
 
Instructions: Read the first two sections of the webpage “Anatomy of the Neuromuscular Junction” and “Physiology of Synaptic Transmission at the Neuromuscular Junction.”
 
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9.1.5 Somatotopic Organization   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 16: Motor Neuron-Muscle Relationships” Link: NCBI Bookshelf’sversion of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 16: Motor Neuron-Muscle Relationships (HTML)
 
Instructions: Read the entire webpage, click on any embedded hyperlinks, and focus on the figures and tables.
 
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9.1.6 Motor Units   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 1: Motor Units and Muscle Receptors” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 1: Motor Units and Muscle Receptors” (HTML)
 
Instructions: Read the section on “Motor Neurons.”
 
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9.1.7 Size Principle   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 1: Motor Units and Muscle Receptors” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 1: Motor Units and Muscle Receptors” (HTML and Adobe Flash)
 
Instructions: Read the section on “Control of Muscle Force.”
 
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9.1.8 Stretch Reflex and Motor Neurons   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” (HTML and Adobe Flash)
 
Instructions: Read the entire chapter. This reading also covers section 9.1.9.
 
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9.1.9 Extensor and Flexor Pairs   Note: This topic is covered by the reading under subunit 9.1.

9.1.10 Golgi Tendon Organs   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 1: Motor Units and Muscle Receptors” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 1: Motor Units and Muscle Receptors” (HTML and Adobe Flash)
 
Instructions: Read the entire webpage. Complete the quiz at the bottom of the page.
 
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9.1.11 Central Pattern Generators   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 16: Spinal Cord Circuitry and Locomotion” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 16:Spinal Cord Circuitry and Locomotion” (HTML)
 
Instructions: Read the entire webpage. Also, click on any embedded hyperlinks, focus on the figures and Box B, and read its contents.
 
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9.1.12 Lower Motor Neuron Syndrome   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 6: Disorders of the Motor System” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 6: Disorders of the Motor System” (HTML)
 
Instructions: Read the section on the “Lower Motor Neuron Syndrome.”
 
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9.1.13 Amyotrophic Lateral Sclerosis   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box C - Amyotrophic Lateral Sclerosis” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box C - Amyotrophic Lateral Sclerosis” (HTML)
 
Instructions: Read the entire webpage.
 
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9.2 Upper Motor Circuits   Note: Decussation refers to the crossing over of nerve fibers from the left side of the body to the right side and vice versa. Most tracts that are discussed in this subunit have some decussation but some do not. Be sure to know which ones do not!

9.2.1 General Upper Motor Control Characteristics   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 17: The Primary Motor Cortex: Upper Motor Neurons That Initiate Complex Voluntary Movements” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 17: The Primary Motor Cortex: Upper Motor Neurons That Initiate Complex Voluntary Movements” (HTML)
 
Instructions: Read the entire webpage.
 
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9.2.2 Colliculus and Colliculospinal Tract / Tectospinal Tract   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” (HTML and Adobe Flash)
 
Instructions: Scroll down and read the paragraph on “Tectospinal tract.”
 
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9.2.3 Red Nucleus and Rubrospinal Tract   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” (HTML and Adobe Flash)
 
Instructions: Scroll down and read the paragraph on the “Rubrospinal tract.”
 
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9.2.4 Reticular Formation and Reticulospinal Tract   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 2: Spinal Reflexes and Descending Motor Pathways” (HTML and Adobe Flash)
 
Instructions: Scroll down and read paragraph on the “Reticulospinal tract.”
 
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9.2.5 Premotor and Motor Cortices   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 3: Motor Cortex” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 3: Motor Cortex” (HTML and Adobe Flash)
 
Instructions: Read the entire webpage.
 
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9.2.6 Homonculus of Primary Motor Cortex   Note: This topic is covered by the reading assigned beneath subunit 9.2.5. Focus on the section beginning “Like the somatosensory cortex of the postcentral gyrus…” and Figure 3.3.

9.2.7 Upper Motor Neuron Syndrome   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 6: Disorders of the Motor System” Link:  The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 6: Disorders of the Motor System” (HTML and Adobe Flash)
 
Instructions: Scroll down and read the paragraph on “Upper Motor Neuron Syndrome.”
 
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9.3 Movement Modulation   9.3.1 Basal Ganglia and Cerebellum Components   - Reading: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 4: Basal Ganglia” Link: The University of Texas’s Neuroscience Online: Dr. James Knierim’s “Ch 4: Basal Ganglia” (HTML)
 
Instructions: Read the entire webpage. This reading also covers sections 9.3.3 and 9.3.4.
 
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9.3.2 Corticostriatal Tract   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 18: Projections to the Basal Ganglia” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 18:Projections to the Basal Ganglia” (HTML)
 
Instructions: Read the entire webpage.
 
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9.3.3 Globus Pallidus and Putamen   Note: This topic is covered by the reading beneath subunit 9.3.1.

9.3.4 Projections from Basal Ganglia   Note: This topic is covered by the reading beneath subunit 9.3.1.

9.3.5 Basal Ganglia Loops   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box C - Basal Ganglia Loops and Non-Motor Brain Functions” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box C - Basal Ganglia Loops and Non-Motor Brain Functions” (HTML)
 
Instructions: Read the entire webpage, and carefully review the figure. 
 
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9.3.6 Spinocerebellar Tract   - Reading: The University of Texas’s Neuroscience Online: Dr. Nachum Dafny’s “Ch 3: Anatomy of the Spinal Cord” Link: The University of Texas’s Neuroscience Online: Dr. Nachum Dafny’s “Ch 3: Anatomy of the Spinal Cord” (HTML)
 
Instructions: Read the webpage.
 
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9.3.7 Cortico-ponto-cerebellar Pathway   - Web Media: YouTube: Drawtoknowit’s “Corticopontocerebellar Pathway” The Saylor Foundation does not yet have materials for this portion of the course. If you are interested in contributing your content to fill this gap or aware of a resource that could be used here, please submit it here.

[Submit Materials](/contribute/)

9.3.8 Cortical Projections to Cerebellum   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Projections to Cerebellum” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Projections to Cerebellum” (HTML)
 
Instructions: Read the entire webpage, and click on the embedded hyperlinks, particularly to explore all figures.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

9.3.9 Cerebellar Circuits   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Circuits within the Cerebellum” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Circuits within the Cerebellum” (HTML)
 
Instructions: Read the entire webpage, and click on the embedded hyperlinks, particularly to explore all figures. 
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

9.4 Visceral Motor Control   9.4.1 Unique Features of Visceral Control   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Central Control of the Visceral Motor Functions” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Central Control of the Visceral Motor Functions” (HTML)
 
Instructions: Read the entire webpage, and click on the embedded hyperlinks, particularly to explore all figures. 
 
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9.4.2 Sympathetic Division   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 21: The Sympathetic Division of the Visceral Motor System” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 21: The Sympathetic Division of the Visceral Motor System” (HTML)
 
Instructions: Read the entire webpage, and click on the embedded hyperlinks, particularly to explore all figures. 
 
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9.4.3 Parasympathetic Division   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 21: The Parasympathetic Division of the Visceral Motor System” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 21: The Parasympathetic Division of the Visceral Motor System” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to all figures.
 
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9.4.4 Enteric System   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 21: The Enteric System” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 21: The Enteric System” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to all figures. 
 
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9.4.5 Solitary Tract and Autonomic Control   - Reading: The University of Texas’s Neuroscience Online: Dr. Patrick Dougherty’s “Ch 3: Central Control of the Nervous System and Thermoregulation” Link: The University of Texas’s Neuroscience Online: Dr. Patrick Dougherty’s “Ch 3: Central Control of the Nervous System and Thermoregulation” (HTML and Adobe Flash)
 
Instructions: Read the section “Circuitry for Hypothalamic Control of the Autonomic Nervous System” and Figure 3.3.

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9.4.6 Central Autonomic Network   - Reading: The University of Texas’s Neuroscience Online: Dr. Patrick Dougherty’s “Ch 3: Central Control of the Nervous System and Thermoregulation” Link: The University of Texas’s Neuroscience Online: Dr. Patrick Dougherty’s “Ch 3: Central Control of the Nervous System and Thermoregulation” (HTML and Adobe Flash)
 
Instructions: Read the paragraphs on “Defining the Central Autonomic Network” and the “Structure of the Central Autonomic Network.”
 
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9.4.7 ?- and ?-Adrenergic Receptors   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 7: Catecholamine Receptors” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch7: Catecholamine Receptors” (HTML)
 
Instructions: Read the entire webpage, and click on all hyperlinks to figures. 
 
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9.4.8 Cholinergic Receptors   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 7: Cholinergic Receptors” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 7: Cholinergic Receptors” (HTML)
 
Instructions: Read the entire webpage, and click on all hyperlinks to figures. 
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Assessment: The Saylor Foundation’s “Unit 9 Assessment” Link: The Saylor Foundation’s “Unit 9 Assessment (PDF)

    Instructions: Complete this quiz after working through Unit 9. The questions are either multiple choice, matching, or labeling diagrams. You can check your answers with the Saylor Foundation’s “Unit 9 Answer Key (PDF).