1886.] 4fao [Stowell. 



continuous with Rx. sensoria. In injected brains the sensory root is sepa- 

 rated from the motor by an arteriole, a small twig from A. basilaris 

 interior. 



In one instance a fascicle from the trapezium crossed the base of the tri- 

 geminus in such relation as to be easily mistaken for fibre from the pons 

 The emargination of the pons may have led to a misconception of the 

 freedom of origin of this root. In one case cited by Wilder (unpublished) 

 a fascicle from the cephalic surface of the sensory root passed centrad near 

 the middle of the pons. - 



Summary — Ectal Origin: 1. Fibres of the pons aie found caudad of 

 the lateral and cephalic moiety of the motor root. 



2. Sometimes the motor root is entirely free of the pons. 



3. The entire motor root never penetrates the pons. 



4. The sensory root never penetrates the pons. 



GANGLION GA.SSERI. 



Synonymy: Ganglion gasseri ; Ganglium gasseri; G. gasserianam ; 

 G. semilunare ; Moles gangliformis ; Intumescentia gangliformis seu semi- 

 lunaris ; Tamia nervosa Halleri ; Ganglion of the fifth nerve, etc. 



Description (Fig. G.) : At the cephalic border of the pons the sensory 

 root is involved in a large flattened ganglion ; this ganglion is lodged in 

 the fossa upon the dorsal surface of the basi-sphenoid bone caudad ot the 

 foramen ovale, Fm. rotundum and Fm. lacerum anterius ; the lateral 

 angle is covered by the ventral wing of the osseous tentorium ; the tento- 

 rium cerebelli is intimately related with the dorsum of G. gasseri, and is 

 with difficulty separated from it. The ganglion is a flattened, irregular 

 body 8 mm. long by 4 mm. wide ; the cephalic border is trichotomous, and 

 gives origin to the principal rami of the sensory root ; the mesal border is 

 nearly straight, and is in contact with the processus clinoideus ; the lateral 

 border is crescentic, and is characterized by a peculiar enlargement at its 

 caudal extremity ; this eminence is the origin of the first rami of the tri- 

 geminus ; one ramus (Pe) enters the hiatus Fallopii, and gives origin to 

 several funiculi, by which it is related with the facial nerve through three 

 canals in the petrous portion of the temporal bone, and also with the 

 glosso-pharyngeal and vagus nerves (through foramen jugulare). From 

 the lateral angle of the eminence a filament (Tn) is given to the tentorium 

 cerebelli ; it lies apposed to the petrosal ramus ectad of the facial nerve.* 



Upon its ventral surface G. gasseri is in relation with the motor root, 

 and also with the large petrosal nerve which proceeds from the geniculate 

 ganglion (this nerve follows the aqueductus fallopii, emerges from the hi- 

 atus fallopii, crosses G. gasseri and joins the vidian nerve just centrad of 

 the vidian canal). 



* This can be best demonstrated by exposing the base of the brain, by the re- 

 moval of the basioceipital and basisphenoid bones, and then with nippers and 

 arthrotome (34, pp. 63. 66), gradually removing the petrous portion of the tem- 

 poral bone. This will expose the tortuous canal with the included nerves. 



