206 CLINICAL DIAGNOSTICS. 



interest. These two morbid conditions have been considered 

 more in detail elsewhere. 



e. Reflex excitability. Reflex movement is a tem- 

 porar\- muscular contraction brought about by stimulating a 

 peripheral (sensory) nerve ending. In order that reflex move- 

 ment may occur the sensory and motor nerve fibres and the 

 reflex center must be intact. Reflex movement is limited to one 

 muscle or muscle group (simple reflex) or it may affect the 

 whole body and in that case may be iiico-ordinated {reflex 

 spasm) or co-ordinated {uiotions of defense or Hii:^hf). The 

 following physiological reflexes are of clinical importance : 



a. Reflexes of the Brain. 



1. Closing of the eyelids. The sensory 

 fibres (trigeminus) of the cornea, conjunctiva and of the skin 

 in the neighborhood of the eye conduct impulses to the medulla 

 oblongata and from that point the facial nerve produces con- 

 traction of the orbicularis of the eyelids. 



2. Sensitiveness to light on j) a r t of 

 the pupil. Increased reflex excitability 

 occurs in tetanus and in strychnine poisoning. Contracted 

 pupil is observed in morphine, eserine and pilocarpine poison- 

 ing. 



Decreased reflex excitability in great 

 mental depression, excessive pain and in dyspnoea of high 

 ■degree. 



Dilated pupil (tnydriasis) occurs in paralysis of 

 the optic nerve (black cataract) and in paralysis of the oculo 

 motor nerve (atropin poisoning). 



b. Spinal Reflexes. 



1. Skin reflexes consist of muscular contractions fol- 

 lowing irritation of sensory peripheral nerves, e. g. manipu- 

 lation or percussion of the walls of the chest or the flank. 

 Touching the anus causes contraction of the sphincter ani 



