CEREBRAL NERVES 



181 



FIG. 174. DIAGRAM SHOWING THE CENTRIPETAL AND CENTRIFUGAL ROOTS OF THE CEREBRAL NERVES 



OF THii SAME EMBRYO AS SHOWN IN FIG. 173. (His.) 



The places of exit of the nerves are marked by dotted circles or ovals. The efferent nerves (III, 

 1 1', ui V, VI, VII, part of IX, XI, and XII) are seen to arise within the nerve-centre from groups of 

 neuroblasts ; the afferent fibres ( V.s, VIII, v and c, most of IX, and X) pass a certain distance 

 inwards, and for the most part also caudalwards in the nerve-centre, and there end. The ganglion- 

 rudiments from which they have grown are not shown here. They are represented in the preceding 

 figure. 



Ill 



IV 



XI 



XII 



t.a. t.p. 

 Fiu. 175. DIAGRAM REPRESENTING THE DISTRIBUTION OF THE CEREBRAL NERVES AND VESSELS OK 



THE HEAD IN AN EMBRYO ABOUT THE FIFTH WEEK; FOUNDED ON RECONSTRUCTIONS BY TANDLER, 



STREETER, AND MALL. (T. H. Bryce.) 



Ill to XII, cerebral nerves ; the sixth is not labelled : it is seen passing forwards below V 3, the 

 mandibular branch of the fifth. 1 to 7, ganglia of the first seven spinal nerves ; a.v. t auditory vesicle ; 

 ^a., truncus aortee ; t.p., truncus pulmonalis ; v.a., vertebral artery. 



K2 



