32 LABORATORY OUTLINE OP NEUROLOGY 



body cavity farther back (esophagus, stomach, etc.). The r. 

 dorsalis vagi contains lateral line fibers for part of the main 

 lateral canal. The r. lateralis vagi supplies the lateral canal 

 behind the region reached by the r. dorsalis. The r. supra- 

 temporalis vagi supplies the anterior end of the lateral canal 

 and the supratemporal canal. All lateral line fibers of the 

 vagus arise by a large root farther forward (rostral) than the 

 other vagus roots. 



The human accessory nerve (XI) is represented by a branch 

 of the vagus (Fig. 5A, trap.) and the hypoglossus (XII) by fibers 

 of the occipital nerves which enter the hypobranchial nerve. 



18. The acoustico-lateral complex. The membranous laby- 

 rinth and the lateral line organs comprise a complex system of 

 sense organs with many features in common (see Johnston 

 ('06), Chap. VII and S. E. Johnson ('17)). Within the lateral 

 line canals and ampullae of Lorenzini are found sense organs 

 which resemble those of the internal ear, and the nerves which 

 supply them enter the same part of the brain, the area acustico- 

 lateralis (see Section 22 and Figs. 2 to 5). The sense organs 

 of the saccule in fishes are sensitive to sound waves; those of 

 the ampullae of the semicircular canals assist in maintaining 

 equilibrium; and those of the lateral line organs are sensitive 

 to water vibrations of a slower rate than the sound wavef re- 

 ceived by the ears, with possibly other functions in addition. 



The nerves terminating in the area acustico-lateralis consti- 

 tute a functional and anatomical system distinct from all other 

 sensory nerves, though peripherally they may be bound up in 

 the same nerve-trunks with other components. They are 

 most closely related with the general cutaneous nerves. They 

 reach their peripheral end-organs through the following nerve 

 trunks (cf . the next section) : 



(1) For the supra-orbital canal from the supra-orbital trunk 

 (this component of this trunk is called the ramus ophthalmicus 

 superficialis VII). 



(2) For the infra-orbital canal from the infra-orbital trunk 

 (this component is called the ramus buccalis VII). 



(3) For the hyomandibular canal from the facial trunk or 

 hyomandibular nerve (called the ramus mandibularis externus 

 VII). 



