612 



THE FUNCTION OF THE SPINAL CORD 



E 



FIG. 303. SCHEMA ILLUSTRATING THE EXPERIMENT FOB DE- 

 TERMINING THE NUMBER OF SEPARATE NERVE IMPULSES PASSING 

 DOWN THE SPINAL CORD UPON STIMULATION OF THE CORTEX. 

 (Horsley.) 



E, E, electrodes, intended to be on the "leg area." Where 

 the cord is interrupted, one non-polarizable electrode is placed 

 over the cut end of the pyramidal fibers going to the lumbar en- 

 largement; the other, on the side of the cord. These lead to the 

 capillary electrometer, in which the column of mercury moves 

 each time an impulse passes. 



(c) Clinical Observations. A study of the 

 clinical pictures of diseases of the spinal cord 

 must prove of especial value if the symptoms 

 are subsequently compared with the record of 

 the autopsy. Naturally, the difficulties con- 

 nected with an accurate localization of motor and 

 sensory defects are minimized in man, owing to 

 his ability to observe and to describe his own 

 symptoms. 



Classification of the Fasciculi of the 

 Spinal Cord. The white matter of the 

 spinal cord is divided into three fasciculi, 

 an anterior, a lateral and a posterior. 1 

 The first two are often called the antero- 

 lateral fasciculi, because the rather scat- 

 tered distribution of the axons forming 

 the anterior root, causes the boundary 

 line between these two columns to become 

 somewhat indefinite. Furthermore, as 

 the cervical and upper thoracic segments 

 of the cord show slight furrow-like depres- 

 sions at the points of exit of the fibers of 

 the anterior roots, the anterior funiculus 

 seems to be composed of two fasciculi, 

 namely, the anteromedian and the antero- 

 lateral. A similar condition exists pos- 

 teriorly, this funiculus appearing as the 

 posteromedian and posterolateral fasciculi. 

 The following subdivisions may easily be 

 made out: 



1. The anterior funiculus comprises the area 

 between the anterior median fissure, and the an- 

 terior root. It is motor in its function and is 

 divided into the: 



(a) Fasciculus cerebrospinalis anterior, also 

 known as Tiirck's column, or the direct (anterior) 



pyramidal tract. 

 It lies next to the 

 median fissure and 

 extends downward 

 >-N as far as the mid- 

 thoracic region. 

 Its caliber de- 

 creases constantly, 

 because the fibers 

 composing it enter 



1 Von Bechterew, 

 Die Funktionender 

 Nervencentra, 

 Jena, 1908-1911, 

 and Edinger, Vergl. 

 Anat. des Gehirns, 

 Leipzig, 1911. 



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