92 THE NERVOUS SYSTEM 



root. This gives the so-called recurrent sensibility of the anterior roots 

 observed in mammals and birds; it does not obtain in the frog. 



For diagnostic purposes, the following table of the relations of the 

 skeletal muscles and the spinal anterior roots as compiled by Kocher 

 from human clinical material is of importance : 



ROOTS. MUSCLES. 



Cervical I. Small neck-muscles, sterno-hyoideus, sterno-thyroideus, omohy- 



oideus. 



" II. ' Sterno-cleido-mastoideus, trapezius. 



" III. Platysma myoides. 



" IV. Scaleni, diaphragma. 



" V. Rhomboidei, supra- and infra-spinatus, coraco-brachialis, biceps, 



brachialis anticus, deltoideus, supinator longus and brevis. 



" VI. Subscapularis, pectorialis major and minor, pronator radii teres, 



pronator quadratus, latissimus dorsi, teres major, triceps, 



serratus magnus. 



" VII. Flexors and extensors of the wrist. 

 " VIII. Long flexors and extensors of the fingers. 

 Dorsal I. All the small muscles of the hand and fingers. 



" I-XII. Muscles of the back. 

 " I-XI. Intercostals. 

 " VII-XII. Muscles of the abdomen. 



Lumbar I. Lower abdominal muscles, quadratus lumborum. 



" II. Cremaster. 



" III. Psoas, sartorius, iliacus, pectineus, adductors of the thighs. 



" IV. Quadriceps femoris, gracilis, obturator externus (?). 



" V. Gluteus medias and minimus, tensor fasciae latse, semitendinosus, 



semimembranosus, biceps femoris. 



Sacral I. Pyriformis, obturator internus, gemelli, quadratus femoris, gluteus 

 maxim us, long extensors of the foot and of the toes, peroneus 

 longus and brevis. 

 " II. Long flexors of the foot and of the toes, large calf-muscles, small 



foot-muscles. 



" III. Ejaculatory and verumontanum muscles. 



" IV. Sphincter and detrusor vesicse, sphincter ani. 



" V. Levator ani. 



The exact varieties of afferent messages which the posterior roots 

 conduct into the cord and so to the cortex cerebri and elsewhere in the 

 brain have not been denned. Whatever "sensations" arrive at all, 

 peripherally started, come into the great highway and coordinating center 

 through these roots (save for those which come by way of the afferent 

 cranial nerves). Touch, pain, muscle and joint-sense, heat-sense, cold- 

 sense, and that ill-defined sensibility which the viscera have, are among 

 the sorts of impressions (some conscious, but many more certainly at 

 least subconscious) conveyed inward by these ventral roots. Much as in 

 case of the efferent roots, the areas supplied by different roots overlap, 

 especially in the extremities, so that every portion, at least of the skin, 

 is supplied with sensation by at least two roots. In some cases the area 

 supplied by the roots of one side extend somewhat into the other side of 

 the body. Head and Dana have shown how certain visceral areas are 

 in close connection with certain regions of the surface of the body the 

 so-called principle of referred pain. Thus, for example, in the same 

 direction, hip-joint disease produces pain at the inside of the knee, and 



