66 LABORATORY OUTLINE OF NEUROLOGY 



centers, and correlation tracts of general cutaneous and deep 

 sensibility (in muscles, joints, etc.) and in the head the optic, 

 auditory, and cerebellar systems. These are all concerned 

 with the adjustment of the body to its external environment. 

 They fall into two subdivisions: (1) exteroceptive, and (2) 

 proprioceptive (see Herrick ('18), Chapters V and IX; Sherring- 

 ton ('06) Chapter IV), whose conduction pathways and corre- 

 lation centers are distinct. The exteroceptive systems respond 

 to external excitations; the proprioceptive systems to excita- 

 tions arising within the body, but subsidiary to the somatic 

 motor reacting system. The optic and cochlear systems con- 

 stitute highly differentiated or special members of the extero- 

 ceptive series, and the vestibular system is similarly a special 

 proprioceptive apparatus. 



(b) Review now the functional composition of the spinal 

 nerves (see Herrick ('18), Figs. 55 and 56) and master the topo- 

 graphic relations of the internal fiber tracts related to the vari- 

 ous functional systems. (The central relations of the visceral 

 sensory components of the spinal nerves are not accurately 

 known.) The primary somatic motor and visceral motor cen- 

 ters of the cord are distinct and are easily recognized in Nissl 

 preparations. The somatic motor neurons lie in the ventral 

 gray column and the visceral motor in the intermedio-lateral 

 column (see Herrick ('18), Fig. 56). 



68. (a) Locate with the aid of the reference books the course 

 of the exteroceptive spinal lemniscus tracts for touch, tempera- 

 ture, and pain, and of the proprioceptive systems (dorsal funi- 

 culi and spino-cerebellar tracts). See Herrick ('18), Chapter 

 VIII, and especially Figs. 59, 63, and 64; on the general somatic 

 systems Chapter XI should also be read in this connection. 

 Howell ('18), Chap. VIII; Starling ('15), Chap. X. 



(b) If pathological preparations illustrating degenerations of 

 spinal cord tracts are available, these should be studied at this 

 time. Consult the larger text-books of neurology, and espe- 

 cially those of neuropathology. (Later sections relating to 

 the tracts of the brain may be illustrated in the same way 

 in any cases where pathological microscopic preparations are 

 available.) 



(c) Valuable information regarding the courses of the fiber 



