THE SYMPATHETIC NERVOUS SYSTEM 



365 



oculomotor nerve. Its cells are probably derived entirely from the semilunar 

 ganglion. 



The sphenopalatine and submaxillary ganglia probably take their origin 

 from migrating cells of the 

 semilunar ganglion, but as 

 they are connected with 

 the geniculate ganglion of 

 the facial nerve some of 

 their cells may be derived 

 from this ganglion. The 

 sphenopalatine ganglion is 

 connected directly with 

 the semilunar ganglion by 

 two communicating rami. 

 The submaxillary ganglion 

 is intimately related to the 

 mandibular division of the 

 trigeminal and through it 

 with the semilunar gang- 

 lion, while the otic ganglion 

 is united to it by a plexus 

 and is related to the glosso- 

 pharyngeal nerve through 

 its tympanic branch. 



The cervical ganglia 

 lose their segmental ar- 

 rangement and represent 

 the fusion of from two to 

 five chain ganglia of the 

 cervical and upper thoracic 

 region. The more distally 

 located prevertebral and vis- 

 ceral ganglia are derived from cells of the neural crest which migrate to a greater 

 distance ventrally (Fig. 347). The cardiac and codiac plexuses may be seen in 

 16 mm. embryos. 



The sympathetic nerve cells give rise to axons and dendrites and are thus 



FIG. 347. The sympathetic system in a 16 mm. human 

 embryo (after Streeter). The ganglionated trunk is heavily 

 shaded. The first and last cervical, thoracic, lumbar, sacral and 

 coccygeal spinal ganglia are numbered, a, aorta; ace, accessory 

 nerve; car, carotid artery; cil, ciliary ganglion; coe, coeliac 

 artery; Ht, heart; nod, nodose ganglion; ot, otic ganglion; pet, 

 petrosal ganglion; s-m, submaxillary ganglion; s. mes., superior 

 mesenteric artery; sph.-p., sphenopalatine ganglion; spl, splanch- 

 nic nerve; st., stomach. (Lewis-Stohr.) 



