Motor Pathways

Question 1

HORIZONTAL*Layer 1: Molecular/Plexiform

Answer 1

-Outermost layer of neurons
-Intra-cortical association
- Axons going horizontally- EFFERENT!

Question 2

HORIZONTAL *Layer 2: External Granular

Answer 2

-Densely packed, small cell bodies
-Intracortical Association- Ipsilateral
- AFFERENT- receiving information

Question 3

HORIZONTAL*Layer 3: External Pyramidal

Answer 3

-Ipsilateral and contralateral cortical fibers
-Inter-hemispheric
-Pyramidal commissural fibers- EFFERENT (mainly excitatory)

Question 4

HORIZONTAL *Layer 4: Internal Granular

Answer 4

-Receives input from thalamus- data entry from the outside
-AFFERENT

Question 5

HORIZONTAL*Layer 5: Internal Pyramidal/Ganglionic

Answer 5

Most critical for speech production, beginning of cortico-bulbar pathway
-Output to brainstem/spinal cord
-Well developed in primary motor cortex
-Pyramidal/Betz- large cells to support large axons
 Stimulate the cranial nerves
o EFFERENT

Question 6

HORIZONTAL*Layer 6: Multiform

Answer 6

• Output to Thalamus

Question 7

VERTICAL

Answer 7

• going across all layers
  Minicolumns: vertical string of approximately 80-100 neurons between cortical layers
  -What the cortex is essentially made up of
  -Core: contains cell bodies, apical dendrites, and unmyelinated axons
  -GABAergic interneurons- provide inhibition between neighboring minicolumns, reinforcing functional segregation
  -Autism: microcolumns are widely spaced
  oLess co-activation of neighboring minicolumns, focus on individual characteristics rather than the whole picture

Question 8

Cortico-bulbar Tract: Path

Answer 8

-Motor Cortex, to cranial and spinal nerves

Question 9

Cortico-bulbar Tract: Function

Answer 9

-Innervate cranial nerves