THE CEREBRUM 171 



the sensory projection systems of sight, hearing, and general 

 sensibility into the cerebral cortex. The subdivision of the 

 diencephalon is summarized in the table on p. 167. The cor- 

 pus striatum in lower vertebrates is an important reflex center; 

 in man its functions seem to be subsidiary to those of the cere- 

 bral cortex for the most part. It consists of two chief masses of 

 gray matter, the caudate and lentiform nuclei, with sheets of 

 white matter between and within these masses. The chief sys- 

 tems of fibers of the white matter are accumulated in the internal 

 capsule which lies between the lentiform nucleus laterally and the 

 caudate nucleus and thalamus medially. Through the internal 

 capsule run the projection fibers which connect the cerebral cor- 

 tex with the lower parts of the brain stem, including the sensory 

 radiations from the thalamus and the descending systems to the 

 pons and brain stem and the great pyramidal tract, which is the 

 voluntary motor path from the cortex to the spinal cord. 



LITERATURE 



HEAD, H., and HOLMES, G. 1911. Sensory Disturbances from Cerebral 

 Lesions, Brain, vol. xxxiv, pp. 109-254. 



HERRICK, C. JUDSON. 1913. Article Brain Anatomy, in Wood's Refer- 

 ence Handbook of the Medical Sciences, 3d ed., vol. ii, pp. 274-342. 



JOHNSTON, J. B. 1906. The Nervous System of Vertebrates, Philadel- 

 phia. 



v. MONAKOW, C. 1895. Experimentelle und pathologische-anatomische 

 Untersuchungen liber die Haubenregion, den Sehhiigel und die Regio sub- 

 thalamica, Arch. f. Psychiat., Bd. 27. 



SACHS, E. 1909. On the Structure and Functional Relations of the Optic 

 Thalamus, Brain, vol. xxxii, pp. 95-186. 



5. Cortico-rubric tract from the motor cortex to the nucleus ruber. 



6 to 10. Pyramidal tract (tractus cortico-spinalis) from the .motor cortex 

 to the spinal cord, with the following parts 



6. To the cervical spinal cord for the muscles of the shoulder. 



7. To the cervjcal cord for the muscles of the arm. 



8. To the cervical cord for the muscles of the hand. 



9. To the lumbar cord for the muscles of the leg. 



10. To the lumbar cord for the muscles of the foot. 



11. Somesthetic radiations from the lateral and ventral nuclei of the 

 thalamus to the cerebral cortex. 



12. Occipito-temporal pontile tract to the pons, and temporo-thalamic 

 tract to the thalamus. 



13. Auditory radiation from the medial geniculate body to the superior 

 temporal gyrus. 



14. Optic radiation from the pulvinar and lateral geniculate body to the 

 cuneus in the occipital lobe of the cortex. 



