642 THE SUPERFICIAL REFLEXES. 



when the skin between the scapulae is stimulated. Its centre corresponds to the 

 lower cervical and upper dorsal region.] 



[The following table, after Gowers, shows the relation of each reflex to the spinal segment or 

 segments on which it depends: 

 Cervical, * . . . 6^ 



" ' " i V Interscapular. 



Dorsal, . U 



I] 



Epigastric. 

 7) 



9 

 10 \ Abdominal. 



11 

 12 j 



Lumbar ' ^Cremasteric. 

 \\ ... Z ) \ Knee Reflex. 



5 I Gluteal. 



Sacral, . . . 1 ^ ^ 



2 t*| -j Plantar. 



. . . . 3j^S I Vesical. 



, 4 [Rectal. 



, 5 J Sexual.] 



Another important diagnostic reflex is the " abdominal reflex," which consists 

 in this, that when the skin of the abdomen is stroked, e.g., with the handle of a 

 percussion-hammer, the abdominal muscles contract. When this reflex is absent 

 on both sides in a cerebral affection, it indicates a diffuse disease of the brain ; its 

 absence on one side indicates a local affection of the opposite half of the brain. 

 The cremasteric, conjunctival, mammillary, pupillary, and nasal reflexes may also 

 be specially investigated. In hemiplegia complicated with cerebral lesions, the 

 reflexes on the paralysed side are diminished, whilst not unfrequently the patellar 

 reflex may be increased. In extensive cerebral affections accompanied by coma the 

 reflexes are absent on both sides, including of course those of the anus and bladder 

 (0. Rosenbach). 



[Horsley finds that in the deepest narcosis produced by nitrous oxide gas the superficial reflexes 

 (c.f/., plantar, conjunctival) are abolished, while the deep (knee-jerk) remain. Anaemia of the 

 lumbar enlargement (compression of the abdominal aorta) causes disappearances of both reflexes 

 (Prevost). Chloroform and asphyxia abolish the deep as well as the superficial reflexes. Horsley 

 regards the so-called deep reflex or knee-jerk not as depending on a centre in the cord, but the 

 contraction of the rectus femoris is due to local irritation of the muscle from sudden elonga- 

 tion. ] 



Deep or Tendon Reflexes. Under pathological conditions, special attention is 

 directed to the so-called tendon reflexes, which depend upon the fact, that a blow 

 upon a tendon (e.g., the quadriceps femoris, tendo Achilles, &c.) discharges a 

 contraction of the corresponding muscle (Westphal, Erb, 1875). The patellar 

 tendon reflex (also called " knee phenomenon ") or simply " knee-reflex," or " knee- 

 jerk," is invariably absent in cases of ataxic tabes dorsalis, while in spastic spinal 

 paralysis it is abnormally strong and extensive (Erb). [The "knee-jerk" is 

 elicited by percussing the ligamentum patellae, and is due to a single spasm of the 

 rectus. The latent period is 0*03 to 0*04 second, and it is argued by Waller and 

 others that it is doubtful if this tendon-reflex is subserved by a spinal nervous arc, 

 while admitting the effect of the spinal cord in modifying the response of the 

 muscle.] Section of the motor nerves abolishes the patellar phenomenon in rabbits 

 (Schultz), and so does section of the cord opposite the 5th and 6th lumbar vertebrae 

 (Tschirjew). Landois finds that in his own person the contraction occurs 0*048 

 second after the blow upon the ligamentum patellae. According to Waller, the 

 patellar reflex and the tendo Achilles reflex occur 0*03 to 0*04 second, and 

 according to Eulenburg, 0*032 second after the blow. According to Westphal, these 

 phenomena are not simple reflex processes, but complex conditions intimately 

 dependent upon the muscle tonus, so that when the tonus of the quadriceps 

 femoris is diminished, the phenomenon is abolished. In order that the phenomenon 

 may take place, it is necessary that the outer part of the posterior column of the 

 spinal cord remain intact ( Westpfial). [The knee-jerk can be increased or reinforced 



