Motor Pathways

Objectives

To describe the course and function of the lateral motor pathways, including Lateral Corticospinal tract, Rubrospinal tract, and Corticobulbar tract
To describe the course and function of the medial motor pathways, including Anterior Corticospinal tract, Corticobulbar tract, Vestibulospinal tract, Tectospinal tract, and Reticulospinal tracts.

Materials

cutouts of cross sections of spinal cord, medulla, pons, cerebellum, thalamus and cerebral cortex

four colors of string to represent axons

four colors of beads to represent cell bodies

Methods

Construct each pathway using a different color. Include the cell bodied, axons, and synaptic sites for each pathway. Label each nucleus and tract as they are relevant.

Use the tables that follow as a guide.

Lateral Motor Pathways

Lateral Corticospinal Tract

Source	Route	Destination
Cell Bodies in Frontal Lobe in Motor Cortex	Internal Capsule. Medullary Pyramid, Pyramidal Decussation, Contralateral Lateral Columns of Spinal Cord	Motor Neurons in dorsolateral region of Anterior Horn

Rubrospinal Tract

Source	Route	Destination
Cell Bodies in Red Nucleus of Midbrain	Contralateral dorsal Medulla and Lateral Columns of Spinal Cord	Motor Neurons in Anterior Horn

Cortiobulbar Tract

Source	Route	Destination
Cell Bodies in Lateral Motor Cortex	Contralateral brainstem	Motor Neurons in Hypoglossal Nucleus and Facial Motor Nucleus

Medial Motor Pathways

Anterior Corticospinal Tract

Source	Route	Destination
Cell Bodies in Frontal Lobe in Motor Cortex	Internal Capsule. Medullary Pyramid, , ipsilateral Lateral Columns of Spinal Cord	Motor Neurons Bilaterally in Anterior Horns

Corticobulbar Tract

Source	Route	Destination
Cell Bodies in Frontal Lobe in Motor Cortex	Bilateral brainstem	Motor Neurons Bilaterally in Cranial Motor Nuclei

Vestibulospinal Tract

Source	Route	Destination
Cell Bodies in Vestibular Nuclei of Medulla	Bilateral Anterior Columns of Spinal Cord	Motor Neurons Bilaterally in in Anterior Horns

Tectospinal Tract

Source	Route	Destination
Cell Bodies in Superior Colliculus of midbrain	Contralateral Medullary Pyramid and Anterior Columns of Spinal Cord	Motor Neurons in Anterior Horns

Reticulospinal Tract

Source	Route	Destination
Cell Bodies in Pons	Anterior Columns of Spinal Cord	Motor Neurons in Anterior Horns (excitatory)
Cell Bodies in Medulla	Lateral Columns of Spinal Cord	Motor Neurons in Anterior Horns (inhibitory)

Discussion

1. What motor information is carried by each of the pathways?

2. What parts of the body are affected by the various pathways?

3. Do any of the pathways cross over? If so, where?

4. What is the significance of crossing over?

5. What is the relationship between the various receptive fields and the somatotopic organization of the cerebral cortex.

Cutouts

Cerebral Cortex (Frontal)

Rostral Midbrain

Caudal Midbrain

Pons

Rostral Medulla

Spinal Cord