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Good Afternoon!!. Michael Lipton, M.D. Objectives. Identify major cortical inputs to the motor pathways List the descending pathways differentiating characteristics Trace the lateral corticospinal tract Identify sites of decussation. Lateral Systems Corticospinal Lateral Rubrospinal.
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Good Afternoon!! Michael Lipton, M.D.
Objectives • Identify major cortical inputs to the motor pathways • List the descending pathways • differentiating characteristics • Trace the lateral corticospinal tract • Identify sites of decussation
Lateral Systems Corticospinal Lateral Rubrospinal Medial systems Corticospinal Anterior Reticulospinal Tectospinal Vestibulospinal Descending Pathways a a
Medial systems • Postural and reflex movement • Proximal and axial muscles • Lateral systems • Fine voluntary movement • Distal muscles
Motor Cortex • M1 = Primary • precentral gyrus • SMA = supplementary • anteromedial • Premotor Area • Anterolateral • Cingulate Motor
Pierre Paul Broca (1824-1880) From an engraving after a portrait (1867) by LaFosse.
Lateral Corticospinal Tract • Most direct pathway • …but 50% of axons ® cerebellum via pons • Voluntary motor control • fine movement/distal muscles • Monosynaptic to hand • gross movement • synapse on spinal interneurons >50% of CS axons
Lateral Corticospinal Tract • M1 (and premotor cortex) • Centrum Semiovale • Corona Radiata • Internal Capsule -- posterior limb • Cerebral Peduncle • Pontine Tegmentum • Medullary Pyramid
Brain Imaging Transverse (Axial) Imaging
Central (Rolandic) Sulcus • Its more posterior than you’d expect • Pearl:follow the superior frontal sulcus back to the precentral sulcus • Remember:All anatomy is variable Roland
Primary Motor & Sensory Cortex • Precentral Sulcus • Primary Motor • Postcentral Sulcus • Primary Sensory Motor Sensory Roland
Functional Imaging (fMRI) Roland What was this person doing?
Wallerian Degeneration • Motor Cortex Injury • Degeneration of first order motor neurons • Outlines the corticospinal tract
Essential Points • Identify major cortical inputs to the motor pathways • M1=primary motor cortex • Premotor Cortex • SMA=supplementary motor area • Cingulate Motor Area
Essential Points • List the descending pathways • Lateral Corticospinal • Anterior Corticospinal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal • [Corticostriatal] Direct cortex effect Indirect cortex effect
Essential Points • Differences • Lateral Corticospinal • Rubrospinal • Anterior Corticospinal • Tectospinal • Vestibulospinal • Reticulospinal Distal muscles Fine movement Proximal and axial muscles Gross and postural movement
Essential Points • Trace the lateral corticospinal tract • M1 (and premotor cortex) • Centrum Semiovale • Corona Radiata • Internal Capsule -- posterior limb • Cerebral Peduncle • Pontine Tegmentum • Medullary Pyramid
Essential Points • Identify sites of decussation • Lateral Corticospinal • Anterior Corticospinal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal Medullary Pyramid Not Applicable Midbrain Tegmentum Midbrain Not Applicable
Brain Imaging Transverse (Axial) Imaging
Coronal Imaging TENT