108 ANATOMY OF THE RAT 



through the anterior lacerated foramen and innervate the 

 external rectus muscles of the eyes. 



The seventh cranial nerves {facial) emerge from the side 

 of the medulla behind the fifth, and leave the cranium 

 through the facial canals just behind the external audi- 

 tory meatuses. They send branches to the lateral surfaces 

 of the muscles of mastication, where they may easily be 

 seen when the skin is removed from the head. 



The eighth nerves (acoustic) arise from the medulla ob- 

 longata behind the seventh, penetrate the auditory cap- 

 sules, and reach the inner ears. 



The ninth nerves (glossopharyngeal) arise from the 

 medulla oblongata close to the tenth. Leaving the skull by 

 the posterior lacerated foramen, they send branches to the 

 pharynx and tongue. They are anterior to, and deeper 

 than, the twelfth nerves, and lie close to the skull. 



The tenth nerves (vagus or pneMmo gastric) arise from 

 the side of the medulla oblongata posterior to the eighth, 

 and leave the cranium through the posterior lacerated 

 foramen. Shortly after emerging they give off the 5W- 

 perior laryngeal nerves to the larynx, then proceed back 

 to the thoracic cavity along the common carotid artery. 

 The recurrent laryngeal nerve is given off near the en- 

 trance of the vagus into the thorax. Trace it forward, on 

 both sides, along the esophagus to the larynx. On the right 

 it turns forward from the vagus dorsal to the subclavian 

 artery, on the left side dorsal to the aortic arch. The tenth 

 nerves in the thorax lie dorsal to the heart and lungs, 

 which they are said to innervate. Passing backward along 

 the esophagus, they penetrate the diaphragm, then inner- 

 vate the stomach. 



The eleventh nerves (accessory) arise from the anterior 

 region of the spinal cord, and from the medulla enter the 

 skull through the foramen magnum, unite with the vagus 



