102 



PHYSIOLOGY OF FARM ANIMALS 



[CH. 



9. Glossopharyngeal, partly sensory and partly motor nerves, supplying 

 the tongue and muscles of the pharynx, and arising from the side of the medulla. 



10. Vagus, or pueiimogastric, partly motor and partly sensory, passing 

 from the sides of the medulla and running down the neck and thorax to the 

 abdomen, and giving branches to the larynx, lungs, heart, oesophagus, stomach, 

 intestines, and liver. 



11. Spinal accessory, motor nerves, arising by ten rootlets fiom the medulla 

 and spinal cord, and supplying certain muscles in the neck. 



12. Hypoglossal, arising from the ventral surface of the medulla and supply- 

 ing the muscles of the tongue. 



The spinal cord is continitoiis with the medulla and passes 

 backwards through the spinal canal inside the vertebral column 

 as far as the lumbar region. Like the brain it is composed of 

 both grey and white matter, but the grey matter in the cord is 



d 



Fig. 49. Section through spinal cord within its mem- 

 branes (after Key and Eetzius, from Schafer). 

 / bundles of posterior root, /( bundles of anterior 

 rootjrt — ^membranes, trabeculaeetc, k, I spaces. 



always centrally placed and gives off symmetrically on each side 

 a dorsal and a ventral horn, and in some regions a lateral horn. 

 The dorsal and ventral horns are clearly shown in any transverse 

 section through the cord. There is a deep dorsal fissure almost 

 joining a shallower and more open ventral fissure, and these 

 fissures divide the cord into two lateral halves excepting for the 

 median portion between them in the middle of which is the 

 central canal. The fissures are partly filled with connective 

 tissue which contains vessels and passes into the substance of 

 the cord supplying it with blood. 



