Ascending And Descending Tracts Of Spinal Cord

Spinal Cord Question And Answers

Question 1. Write a short note on laminar organization in spinal cord.

Laminar organization in spinal cord

Spinal Cord Spinal Gray Matter

  • In thick section, neurons of the spinal cord appear to have a laminar arrangement
  • Starting from tip of dorsal horn towards the vertical horn ten layers are recognized
  • These are as follows:
  1. Lamina 1: Corresponds to posteromarginal nucleus
  2. Lamina 2: Corresponds to substantia gelatinosa
  3. Lamina 3 and 4: Corresponds to nucleus proprius
  4. Lamina 5 and 6: Corresponds to the base of dorsal column
  5. Lamina 7: Occupies the territory between dorsal and ventral horns and contains cells that function as interneurons. Nucleus dorsalis, intermediolateral, intermediomedial are clear cell columns recognized within this lamina
  6. Lamina 8: Corresponds to ventral horn in thoracic segments
  7. Lamina 9: Includes lateral group of nuclei of the ventral horn, supply skeletal muscles of limb
  8. Lamina 10: Surrounds the central canal and contains decussating axons, neuroglia, and some neurons with interneuron properly.

Question 2. Write a short note on tracts of the spinal cord.

Tracts of the spinal cord

Spinal Cord Cross-section Of Spinal Cord To Show Ascending And Descending Tracts In White Matter

  • A collection of nerve fibers that connects two masses of gray matter within the central nervous system (CNS) is called a tract
  • These are ascending and descending tracts, and named after gray matter connected by them.

Spinal Cord Descending Tracts: These include

  • The pyramidal tract/corticospinal tracts
  • Descends from cerebral cortex to spinal cord and consists of:
    • Lateral corticospinal tract
    • Anterior corticospinal tract.
  • The extrapyramidal tracts include:
    • Rubrospinal tract
    • Medial reticulospinal tract
    • Lateral reticulospinal tract
    • Olivospinal tract
    • Vestibulospinal tract
    • Tectospinal tract.
  • Pyramidal tracts
    • These are formed by axons of pyramidal cells lying in the motor area of cerebral cortex
    • From the base the first pass through the internal capsule, midbrain, pons, and medulla
    • At the lower border of medulla, 80% of fiers cross to opposite side, and is called as pyramidal decussation and enter the lateral column and descends on lateral corticospinal tract
    • The fibers which do not cross enter the anterior column and descend as anterior corticospinal tract.

Spinal Cord Course Of The Corticospinal Tracts

Spinal Cord Indirect Pathways Through Which The Cerebral Cortrex May Influence The Spinal Cord

Spinal Cord Ascending Tracts: These include the following

  • Lateral spinothalamic tract
  • Anterior spinothalamic tract
  • Fasciculus gracilis
  • Fasciculus cuneatus
  • Anterior spinocerebellar tract
  • Posterior spinocerebellar tract
  • Spino-olivary tract
  • Spinotectal tract.

Spinal Cord Multiple Choice Question And Answers

Question 1. All of the following are descending tracts except:

  1. Anterior corticospinal tract
  2. Rubrospinal tract
  3. Spino-olivary tract
  4. Olivospinal tract

Answer: 3. Spino-olivary tract

Question 2. All of the following statements about the laminar organization of spinal cord is correct except:

  1. Lamina 1 corresponds to posteromarginal sulcus
  2. Lamina 7 includes the intermediomedial, inter mediolateral and dorsal nuclei
  3. Lamina 5 corresponds to the neck of the dorsal gray column
  4. Lamina 8 occupies most of the dorsal horn in thoracic segments.

Answer: 4. Lamina 8 occupies most of the dorsal horn in thoracic segments.

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