1. CEREBRAL TRACTS

2. Categories of Tracts Association: Confined to a given hemisphere.
Connect regions of the same hemisphere.
Commissural:
Interconnect the two hemispheres.

3. Categories of Tracts Projection Tracts: Form internal capsule.
Make up ascending and descending tracts.
Connect hemispheres to other parts of brain and spinal cord.

4. Association Tracts: Examples
Arcuate
Cingulum
Superior longitudinal fasciculus
Superior occipitofrontal fasciculus
Inferior occipitofrontal fasciculus
Uncinate fasciculus

5. Arcuate Tracts
Interconnect adjacent gyri.

6. Cingulum
Connects frontal, parietal and temporal cortical areas on the medial side of each hemisphere.

7. Superior Longitudinal Fasciculus
Interconnects areas within the frontal, parietal, occipital, and temporal lobes.

8. Superior Occipitofrontal Fasciculus
Located in medial part of hemisphere underneath lateral extension of corpus callosum.
Interconnects the frontal lobe with more posterior parts of hemisphere.

9. Inferior Occipitofrontal Fasciculus
Runs between the occipital and frontal lobes in the lateral part of each hemisphere under the insula.

10. Uncinate Fasciculus Makes a sharp bend around the lateral fissure.
Interconnects the orbital surface of the frontal lobe with the rostral part of the temporal lobe.

11. Commissural Tracts: Examples
Corpus callosum
Anterior commissure
Posterior commissure
Hippocampal commissure

12. Corpus Callosum Contains about 300 million fibers.
Interconnects neocortical areas in all lobes.
Unifies awareness and attention between the two lobes.
Permits a sharing of learning and memory.

13. Corpus Callosum: Subdivisions
Splenium = Wide caudal part.
Body = Large midportion.
Genu = Anterior part.
Rostrum is continuous with lamina terminalis.

14. Anterior Commissure
Interconnects areas within the two temporal lobes.

15. Posterior Commissure
Connects cerebral hemispheres with superior colliculi.

16. Hippocampal Commissure
Interconnects two hippocampal formations.

17. Projection Tracts: Types
Corticopetal:
To cerebral cortex.
Corticofugal:
From cerebral cortex.

18. Corticopetal Projection Fibers
Mostly from thalamus.
Form part of internal capsule.
Diverge toward cerebral cortex.
Form part of corona radiata.

19. Corticofugal Projection Fibers
Originate in different parts of cerebral cortex.
Converge toward:
Basal nuclei.
Thalamus.
Form part of corona radiata.
Form part of internal capsule.

20. Projection Tract Examples
Thalamic radiation
Corticopontine
Corticobulbar
Corticospinal
Corticoreticular
Optic radiation
Fornix

21. Thalamic Radiation
Corticothalamic fibers project within internal capsule from cerebral cortex to thalamus.
Thalamocortical fibers project within internal capsule from thalamus to cerebral cortex.

22. Corticopontine Projections
Corticopontine fibers projects to pontine nuclei in the pons.
Pontine nuclei project to cerebrellum.

23. Corticobulbar Projections
Part of pyramidal tracts.
Originate mostly in motor cortex.
Project to cranial nerve nuclei in brainstem.

24. Corticospinal Projections
Part of pyramidal tracts.
Originate mostly in motor cortex.
Project to cell groups throughout all parts of spinal cord.

25. Corticoreticular Projections
Originate in motor and somatosensory cortex.
Project to brainstem reticular formations.

26. Optic Radiation = Geniculocalcarine tract.
Originates in lateral geniculate body.
Runs in lateral direction in the internal capsule.
Makes a sharp bend (= Meyer’s loop).
Runs in caudal direction toward calcarine fissure in occipital lobe.

27. Fornix
Major projection system between the hippocampus in temporal lobe and the diencephalon.