SPINAL CORD AS A PATH OF CONDUCTION. 171 



Descending Tracts in the Posterior Column Comma Tract ; 

 Oval Field. In the posterior columns several tracts of descending 

 fibers have been described. The comma tract of Schultze is 

 found in the cervical and the upper thoracic cord. The bundle 

 lies at the border-line between the columns of.Goll'and Burdach. 

 In the lower regions of the cord, lumbar and sacral, similar small 

 areas of descending fibers are found oval field (Flechsig), median 

 triangle (Gombault and Philippe) which represent possibly 

 different systems. It is probable that these fibers belong to the 

 group of long association fibers connecting distant portions of the 

 cord. Nothing is known regarding their physiology. 



Descending Tracts in the Anterolateral Column. The prepyram- 

 idal tract, known also as Monakow's bundle, the fasciculus inter- 

 mediolateralis, or the rubrospinal tract, is a conspicuous bundle 

 forming a wedge-shaped or triangular area in the lateral columns 

 between the crossed pyramidal tract and the tract of Gowers, or, 

 perhaps, more correctly speaking, forming the anterior portion 

 of the crossed pyramidal tract; the two systems being more or 

 less intermingled. The fibers composing this bundle are descending 

 fibers that take their origin in the midbrain in the cells of the red 

 nucleus. Shortly after their origin they cross to the opposite 

 side, and passing through the pon and medulla enter the spinal 

 cord in the lateral columns, in which they may be detected as far 

 as the sacral region. Its fibers terminate around cells lying in the 

 posterior part of the anterior horn of gray matter whose axons 

 in turn probably emerge through the anterior roots. This tract, 

 therefore, constitutes a crossed motor path from midbrain to the 

 anterior roots, and, since the red nucleus in turn is connected 

 with the cerebrum, either directly or by way of the cerebellum, it 

 represents a corticospinal motor path in addition to that offered 

 by the pyramidal system. 



The vestibulospinal fibers lie anterior to the preceding tract 

 in the anterolateral ground bundle; they may extend into the 

 anterior column as far as the direct pyramidal tract. These fibers 

 originate in the nucleus of Deiters. In the cord the fibers end 

 around cells in the anterior horn. Since the Deiters nucleus forms 

 a termination for the sensory fibers of the vestibular branch of the 

 eighth cranial nerve, and since these fibers are believed to give us 

 a sense of the position of the body and to be concerned in the reflex 

 adjustment of the muscles in the movements used to maintain 

 equilibrium, their connection in Deiters' nucleus with a spinal motor 

 path becomes very significant as furnishing a reflex arc through 

 which sensory impressions from the vestibular apparatus in the ear 

 may automatically control the musculature of the body. A number 

 of other descending paths in the anterior and lateral columns have 



