Theme 5. HIERARCHY AND ORGANIZATION OF CONTROL SYSTEMS OF MOVEMENT

i. Upper neuron control of the brainstem and the spinal cord,
Lateral and medial descending motor neural pathways.

ii. Motor control hierarchy.

iii. The primary motor and premotor cortex. Planning,
programming and execution of motor functions.

iv. Descending cortical tracts in red in the image. Descending pathways

v. The upper motor neuron syndrome.

Somatic Motor System

3 Classes of movement

Rhythmic, repetititve motions

Reflex response

Voluntary movement

Motor Control System

Cerebral cortex motor areas

Brainsteam

Spinal cord

UMNs bodies are found in the cerebral
cortex and in the brainstem

They exert supranuclear control of the
LMNs of the cranial and spinal nerves.

UMNs are responsable for conveying
impulses for voluntary motor activity.

UMNs synapse indirectly by interneurons
rather tan directly on LMNs of the spinal cord

Upper motor neurons Actions

2.- Inhibition

3.- Gating of reflexes

  1. Excitation

PRECOMAND LEVEL

SEGMENTAL LEVEL

PROJECTION LEVEL

Motor cortex

Brainstem

Basal ganglia

Cerebellum

Spinal cord

SMC is responsable for planning of complex
movements of the contralateral extremities.

The primary motor cortex directly control spinal motor neurons through the pyramidal tracts for precise movement

MPC projects directly to the spinal cord to control trunk and proximal limbs necessary for posture and coordination

Direct Pathways

Corticobulbar tract

Anterior corticospinal tract

Lateral corticospinal tract

Fine movements of extremities/fingers

Anterior LMNs spinal cord

Head/face/neck.

Axial and limb proximal muscles

Anterior LMNs spinal cord.

Damage to the descending motor pathways anywhere

Chronic hypertonia

Other symptoms:

Acute hypotonia

Spinal shock.

Rigidity/spasticity.

Hyperactive clonus

Hyporeflexia

Loss of the ability to performfine movements

Rubrospinal tract

Medullary (lateral) reticulospinal tract

Lateral costicospinal (pyramidal) tract

Pontoresticulospinal (medial reticulospinal) tract

Interfascicular (semilunar) fasciculus

Vestibulospinal tract

Anterior (ventral) costicospinal tract

Tecstospinal tract

Lateral corticospinal (pyramidal) tract

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