Cerebral Cortex, Spinal Cord, Thalamus Flashcards
Cerebral cortex features
- 2-4mm thick
- highly convoluted gray substance
- comprises half of brains volume
Divisions of cerebral cortex
Neocortex (isocortex) 6 layers
Allocortex 3-5 layers (paleocortex and archiocortex)
CLP layer I
Molecular layer - superficial layer rich in horizontally oriented dendrites and axons
CLP layer II
External granular layer - mostly smaller neurons and few pyramidal cells. Receives input from layer III
CLP Layer III
External pyramidal cell layer - contains medium sized pyramidal neurons. Gives rise to association and commissural axons that terminate in layer II
CPL layer IV
Internal granular layer - contains mainly stellate neurons and few pyramidal neurons. RECEIVES THALAMIC INPUT!
CPL layer V
Internal pyramidal layer - contains large pyramidal neurons, including giant Betz cells, axons become projection fibers to subcortical structures and spinal cord
CPL layer VI
Multiform layer - contains multiple cell types. INCLUDES PYRAMIDAL CELLS THAT PROJECT TO THALAMUS
Association fibers
Connects portions of cortex within the same hemisphere. Axons of neurons that reside in layer III and terminate in layer II at their destination. Can be long or short
Commissural fibers
Axons interconnect hemispheres. Majority in corpus callosum. There are anterior and posterior commissures
Projection fibers
Axons mainly within layer V and project downward to deep parts of the cerebrum, brain stem, or spinal cord
Corticostriatal
Layer V to caudate nucleus / putamen
Corticorubral
Layer V to red nucleus
Corticopontine
Layer V to pons
Corticoreticular
Layer V to brain stem reticular formation
