THE VERTEBRAL COLUMN 



521 



of an intercostal vessel, it may ultimately point through the 

 muscles of the back. 



When the disease originates in the mid-thoracic region, 

 muscular spasm produces boarding and rigidity of the sacro- 

 spinales and, sometimes, the abdominal muscles. Pain may be 



Posterior column of spinal medulla 



Posterior nerve-root 

 Anterior nerve-root | 

 Spinal ganglion 

 or rainus (medial branch) ^^^ff^ 



Anterior column of spinal medulla 



Posterior rai 



Posterior ramus (lateral brand 



Recurrent meningeal branc 



Gray ramus coinmimican* 



Splanchnic branch (white rainus ^ 



communi 



Anterior ram 



Lateral branch (poste 

 subdivis: 



Lateral branch 



ateral branch (anterior . 

 subdivision) 



^ 



Oiingliated sympathetic 



trunk 



Efferent (vaso-motor) 



branch 



Afferent viscero- 

 inhibitory branch 



FIG. 159. Scheme of the Distribution of a Typical Spinal Nerve. 



experienced in the back, but it is very frequently referred to the 

 anterior abdominal wall, and it may then lead to errors in 

 diagnosis. Abscesses may point through the muscles of the 

 back, or they may follow the course of an intercostal nerve 

 and come to the surface by tracking along its lateral cutaneous 

 branch (Fig. 159). 



