SPILOPLAXIA 



1354 



SPINAL 



or wandering maculae of the skin. Also, a synonym 

 of Elephantiasis gracorum . 



Spiloplaxia (spi-lo-plaks' -e-ah) [airiXog, spot; nM^, a 

 broad surface]. A condition marked by the large red 

 spots symptomatic of elephantiasis ; seen also in some 

 cases of pellagra. 



Spilosis poliosis. Synonym of Canities. 



Spilus {ipi'-lus) [oKiAoq, a spot]. A mole or colored 

 mark on the skin ; nevus. 



Spina (spi'-nafi) [L. , the backbone]. I. A thorn. 2. 

 The spine. S. bifida, a hernia of the spinal mem- 

 branes through a cleft or abnormality of the lower 

 part of the vertebral column ; called, also, Hydror- 

 rhachitis. S. cervina. Same as Buckthorn. S. 

 helicis. See Crista helicis. S. suprameatum, an 

 elevation just above the superior angle oi the mastoid 

 process of the temporal bone. It appears to be the 

 posterior part of the zygomatic line. It is an import- 

 ant guide in the operation of opening the mastoid. 

 S. ventosa, a rarefying form of osteitis in which the 

 bone is eroded or destroyed, and the subperiosteal 

 tissue and osseous marrow contain numerous small 

 cells with transuded red blood-corpuscles. It is fre- 

 quently a result of syphilis. 



Spinal \spi'-nal) \spina, spine]. Pertaining to the 

 spine. S. Accessory Nerve. See Nerve. S. 

 Accessory Spasm. See Tic rotatoire. S. Bulb, 



Transection of the Spinal Cord in the Cervical 

 Region. 

 A. Ventral gray column, a. Ventral white column. /. Lat- 

 eral white column, ac. Ventral commissure, ar. Ventral 

 roots, af. Ventral median fissure, it. Intermediolateral 

 gray column, vc. Vesicular column of Clarke. P. Dorsal 

 gray column, p. Dorsal-external white column, pm. Dor- 

 sal-median column, pc. Dorsal commissure, cc. Central 

 canal, pr. Dorsal roots //. Dorsal-median fissure, ae 

 and at. External and internal ventral vesicular columns. 

 sg. Substantia gelatinosa. (Sevan Lewis.) 



the oblongata. S. Canal. See Canal, Vertebral. S. 

 Centers, motor centers situated in the spine. The 

 principal are the cilio-spinal, connected with the dilata- 

 tion of the pupil ; the auro-spinal ; the vesico-spinal ; 

 the erection-center; the ejaculatory center; the par- 

 turition, and numerous vasomotor centers. S. Col- 



umn, the vertebral column, composed of 33 vertebrae. 

 S. Cord, the myelon, or medulla spinalis; the neura! 

 structure occupying the vertebral canal and extending 

 from the atlas to the first lumbar vertebra, and termi- 

 nating in the Jilum terminate. It is the great conduct- 



J 3 ™- 



1& 



&*■ 



Transection of the Spinal Cord in the Thoracic 

 Region. (Bevan Lewis.) 



ing medium of nervous impulses both afferent and 

 efferent and within itself from side to side, and is the 

 great organ of reflexes. It consists of white matter 

 externally and gray matter internally. Fissures, the 



Transection of the Spinal Cord in the Lumbar 

 Region. (Bevan Lewis.) 



ventral median, dorsal median, and two lateral, 

 divide each half of the cord into four Columns, a 

 ventral, lateral, dorsal, and dorsal median. In the 

 Ventral Column lie the uncrossed, ventral, or direc 



