296 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



ventral root passes upwards and splits into two bundles, 

 one penetrating the dorsal, the other the ventral ganglion. 

 Both roots emerge from the atlas vertebra by a single 

 foramen (fig. 17). 



The following nerves arise from the dorsal ganglion : 



1. R. communicans (r, com. 2). — A sensory nerve 

 arising from the extreme dorsal tip of the dorsal ganglion. 

 Passes upwards and forwards, bends forwards over the 

 roof of the skull, and fuses with the R. spinosus c. of the 

 first spinal nerve (q. v.). 



2. R. spinosus (r. sp. 2). — A motor nerve passing 

 upwards internal to the dorsal ganglion. After giving off 

 a fine motor twig below, which passes upwards external 

 to the dorsal ganglion (and not shown in the chart), it 

 liberates in front and above a larger motor nerve which at 

 once splits into two bundles coursing laterally in the 

 dorsal musculature — one anteriorly and the other pos- 

 teriorly (see chart). Above, it receives the sensory R. 

 communicans from the third spinal nerve, in the typical 

 manner, and bends forwards over the roof of the skull, 

 keeping very close to the middle line. 



The following nerves arise from the ventral ganglion : 



1. R. medius (r. m. 2). — A mostly motor nerve, 

 which perforates the ganglion, and then turns laterally 

 backwards in the dorsal musculature. It breaks into two 

 — one coursing in the dorsal musculature above the R. 

 lateralis profundus vagi, and the other crossing below it 

 into the lateral musculature, and supplying the muscles 

 in these regions. It seems to contain some sensory fibres 

 also. 



2. R. yentralis (r. v. 2). — A mixed nerve perforating 

 the ganglion and coursing downwards and backwards over 

 the kidney and approximating to the R. ventralis of the 

 first spinal nerve. It receives two Rami communicantes 



