I3I4 



A MANUAL OF ANATOMY 



Linea Splendens 



ll|:.Cauda Equina 



— -Filum Terminale 



the theca which blends with it. It is also composed of pia mater 

 prolonged downwards from the contis medullaris, and reinforced by 

 fibres derived from the lower portions of the Hgamenta denticulata 



and linea splendens. Its lower part is 

 purely fibrous. 



Cauda Equina. — ^This is situated within 

 the lower part of the theca. It consists 

 of the lumbar, sacral, and coccygeal 

 nerves of each side, which are arranged 

 in the form of a leash, and the filum 

 terminale lies in the median line between 

 the two nerve-leashes. On account of 

 the high origins of the individual nerves, 

 relatively to the positions of the inter- 

 vertebral foramina through which they 

 Conus Medullaris pass, the direction of the nerves is almost 

 vertical until they reach the level of their 

 respective foramina of exit. 



Fissures of the Spinal Cord.— The spinal 

 cord, which is somewhat flattened in 

 front and behind, is incompletely divided 

 into two symmetrical halves by two 

 median fissures, anterior and posterior. 

 The anterior median fissure extends 

 into the cord for one-third of its thick- 

 ness from before backwards, and it con- 

 tains a fold of the pia mater. At the 

 bottom of the fissure the transverse * 

 band of nerve-fibres, called the anterior m 

 white commissure, crosses between the 

 two halves of the cord. The posterior 

 median fissure, though so named, is not 

 an actual fissure like the anterior, and 

 does not contain a fold of the pia mater. It is just wide enough 

 to contain a septum formed by neuroglia, and it extends into the 

 cord for about half of its thickness from before backwards. The 

 posterior grey commissure lies at the bottom of the fissure. The 

 anterior median fissure is more distinct and wider than the pos- 

 terior, but it is not so deep. 



Each half of the cord presents a groove along the line of entrance 

 o;f the fasciculi of the posterior nerve-roots, called the postero-Iateral 

 sulcus, but there is no similar groove along the line of emergence of 

 the fasciculi of the anterior nerve-roots, these being spread over an 

 area of some breadth. By means of the postero-Iateral sulcus on 

 the one hand and the area corresponding to the emergence of the 

 fasciculi of the anterior nerve roots on the other, each half of the 

 spinal cord is divided superficially into three columns, anterior, | 

 lateral, and posterior. I 



The anterior column is situated between the anterior median 



Fig. 549. — The Terminal 

 Part of the Spinal Cord, 

 AND THE Cauda Equina. 



