FUNCTIONAL ANALYSIS, CENTRAL AND PERIPHERAL G9 



and subsequent studies the peripheral nervous system of the head 

 was analyzed into functional systems as follows: 



1. Somatic sensory fibers of two groups. — (1) Exteroceptive sys- 

 tems, including (a) the specialized olfactory (in part), optic, audi- 

 tory, and lateral-line nerves with differentiated end-organs, and (6) 

 the nerves of general cutaneous and deep sensibility with simple free 

 endings, these entering chiefly in the V nerve root with some in the 

 VII, IX, and X roots. (2) Proprioceptive fibers from specialized end- 

 organs of the internal ear and (probabljO lateral-line organs and also 

 fibers from muscles, tendons, and other deep tissues. Here belongs 

 also the peculiar mesencephalic root of the V nerve. See chapter x for 

 further comments on the proprioceptive system. 



2. Visceral sensory fibers of two types. — (1) With specialized end- 

 organs, viz., the olfactory organ (in part) and the taste buds, the 

 latter entering by the VII, IX, and X nerve roots. (2) Fibers of gen- 

 eral visceral sensibility with free endings, entering in the same roots 

 as the preceding and mingled with them. 



3. Somatic motor fibers. — Somatic motor fibers which supply stri- 

 ated muscles derived from the embryonic somites, those in Amblys- 

 toma being limited to the nerves of the extrinsic muscles of the eye- 

 ball in the III, IV, and VI nerves. 



4. Visceral efferent fibers of two types. — (1) Special visceral motor 

 fibers of cranial nerves supplying striated muscles, not of somitic 

 origin, related with the visceral skeleton, jaws, hyoid, branchial 

 arches, and their drivatives (in the V, VII, IX, and X roots). 

 (2) Preganglionic fibers of the general visceral (autonomic) system, 

 terminating in sympathetic and parasympathetic ganglia, where they 

 activate postganglionic fibers distributed to unstriated and cardiac 

 muscles and glands (in the III, VII, IX, and X roots). The last sys- 

 tem is not further considered in this work. For application of this 

 analysis to the human nervous system see my Introduction to Neurol- 

 ogy ('31a, chaps, v and ix). 



This analysis has yielded our most useful clues for resolution of the 

 complexity of both peripheral nerves and brain. Descriptions of the 

 peripheral end-organs and the courses of the nerves do not lie within 

 the scope of this work. Some of these details which are significant for 

 understanding their central connections are included in chapter x. 



