276 



FUNCTIONS OF THE NERVOUS SYSTEM. 



Posterior Pyramids, or Corpora Pyramidalia Posteriora. The connections 

 of these with the Brain above, and with the Spinal Cord below, will be now 

 traced.* 



[Fig. 139. 





IV 



Transverse section of the medulla oblongata through the lower third of the olivary bodies. (From Stil- 

 ling.) Magnified 4 diameters. 



a. Anterior fissure. 6. Fissure of the calamus scriplorius. c. Raphg. d. Anterior columns, e. La- 

 teral columns, f. Posterior columns, g. Nucleus of the hypoglossal nerve, containing large vesicles. 

 h. Nucleus of the vagus nerve, i, i. Gelatinous substance, k, k. Roots of the vagus nerve. /. Roots of 

 the hypoglossal, or ninth nerve, in. A thick bundle of white longitudinal fibres connected with the root 

 of the vagus, n. Soft column (Zartstrang, Stilling), o. Wedge-like column (Keelstrang, Stilling), p. 

 Transverse and arciform fibres, q. Nucleus of the olivary bodies, r. The large nucleus of the pyramid. 

 s, s, s. The small nuclei of the pyramid, it. A mass of grey substance near the nucleus of the olives 

 (Oliven-Nebenkern). u, q, r, are traversed by numerous fibres passing in a transverse semicircular direc- 

 tion, v, w. Arciform fibres, x. Grey fibres.] 



351. As our object, however, is rather Physiological than purely Anato- 

 mical, we shall commence with a description of the motor and sensory tracts, 

 which may, according to Sir C. Bell,t be very distinctly separated in the Pons 



* Great diversities will be found in the accounts given of those connections by different 

 Authors; some of which are attributable to a variation in the use of terms, which must not 

 pass unnoticed. By the majority of Anatomists, the name of Corpora Uestilbrmia is given to 

 the Ccrebdlar Columns; and its designation, therefore, it seems advisable to retain. Some, 

 however, and amongst them Dr. .1. Reid, in his late very excellent description of the Ana- 

 tomy of the .Medulla Oblongata (Kdinb. Mod. & Surg. Journal, Jan. 1841), give the name to 

 the columns that pass up from the posterior division of the spinal cord into the crus cerebri, 

 which are here called (alter Sir C. Bell) the posterior pyramids; and apply the terms 

 Posterior Pyramids to the Cerebellar column. The truth is that, as Sir C. Bell has justly 

 observed, all the tracts of fibrous mailer connecting the Drain with the Spinal Cord, have a 

 somewhat jii/nnniilul Jbrm ; and it might be added that all have something of a restiform or 

 cord-like-aspect 



f Philosophical Transactions, 1835. 



