Anatomy Bones and Muscles · MU Pleven

149. Efferent motor systems. Extrapyramidal system.

Covers the motor system, contrasting the pyramidal pathways (corticobulbar and corticospinal tracts from the primary motor cortex) with the extrapyramidal pathways, which are split into medial routes (vestibulospinal, tectospinal, reticulospinal) and a lateral rubrospinal route. Includes a summary section listing upper and lower motor neurons and decussation points for each tract, plus diagrams. The note also goes on to the limbic system, the PNS and ontogenesis, which lie outside this topic.

Inside: 16 sections · 12 labelled pictures · 10 flashcards · 15 min

Topic 148 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 16 sections, about 2,081 words (15 min of reading), with 10 flashcards.

In this note

  1. Introduction
  2. MOTOR SYSTEM
  3. Pyramidal System :
  4. Extrapyramidal tract :
  5. Corticonuclear (Corticobulber) system:
  6. Corticospinal :
  7. Oculomotor :
  8. Medial pathway :
  9. Lateral pathway :
  10. Summary:
  11. LIMBIC SYSTEM
  12. Structures :
  13. Functions :
  14. Connections between the limbic structures :
  15. The papez circuit :
  16. PNS

Introduction

177+178

MOTOR SYSTEM

The motor system is a complex network of structures and pathways within the nervous system that coordinates and controls voluntary and involuntary movements.

Pyramidal System :

  • This system begins from the pyramidal cells of the primary motor cortex.
  • Axons of these upper neurons descend into the brain stem and spinal cord to synapse with on lower motor neurons that control skeletal muscles.
  • It includes 3 pairs of tracts:
  • Cortico-bulbar tracts: (to motor cranial nerves nuclei in the brain stem).
  • Lateral cortico-spinal tracts: to the spinal cord, running in the lateral white column.
  • Anterior cortico-spinal tracts: to the spinal cord, running in the anterior white column

Extrapyramidal tract :

  • This system is concerned with subconscious regulation of muscle tone and movement, in addition to subconscious control of the balance needed for each movement.
  • It includes 2 pathways:
  • Medial pathway: controlling movements of trunk and proximal limb muscles (vestibulo-spinal, tecto-spinal, and reticulo-spinal tracts).
  • Lateral pathway: controlling distal limb muscles with its more discrete movements (rubro-spinal tracts).

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