QUESTIONS AND ANSWERS 75 



from the sympathetic system are seen : the ophthalmic or ciliary, the 

 sphenopalatine or Meckel's, and the otic or Arnold's. 



Describe the sixth pair of cranial nerves. 



The abducens originates superficially from the medulla behind 

 the pons and, deeply, from the inferior pyramid and lateral tract of 

 the medulla. 



It leaves the cranial cavity with the ophthalmic branch of the 

 fifth, and is distributed to the external rectus muscle of the eye. 



Describe the seventh pair of cranial nerves, the facial. 



Originates superficially from the medulla behind the pons and, 

 deeply, in the floor of the fourth ventricle. It escapes from the 

 cranial cavity through the internal auditory meatus with the eighth 

 pair, enters the aqueduct of Fallopius, has the geniculate ganglion 

 developed on it and passes out through the stylomastoid foramen to 

 the muscles of the face, ears, lips, nostrils and eyelids. 



Branches : great petrossal, to Meckel 's ganglion ; small petrossal, 

 to otic ganglion ; tympanitic, to stapedius ; chorda tympani, to tongue 

 and mouth; muscular, to occipitostyloid, digastric, stylohyoid and 

 cervical muscles ; auricular, to the ear and face. 



Describe the auditory nerve (eighth pair). 



Originates in the medulla, below the seventh pair. Leaves the 

 cranial cavity with the seventh pair and is distributed to the internal 

 ear by two branches, the cochlear and the vestibular. 



Describe the ninth pair of cranial nerves, glossopharyngeal. 



Originates in the medulla and more deeply in the floor of the 

 fourth ventricle. Leaves the cranial cavity by the posterior fora- 

 men lacerum and is distributed to the back part of the tongue, and 

 pharynx. 



Branches: Jacobson's nerve to the tympanum; filaments com- 

 municating with the superior cervical ganglion; carotid and 

 pharyngeal. 



Give the origin and the distribution of the pneumogastric nerve. 



The pneumogastric, vagus or tenth pair, originates in the 

 medulla and passes through the posterior lacerated foramen to be 

 distributed to the oesophagus, pharynx, lungs, bronchi, trachea, 

 heart, stomach and intestines. Its principal branches are: 1, 

 superior laryngeal to the mucous membrane of the larynx and crico- 

 thyroid muscle ; 2, inferior laryngeal to all the muscles of the larynx 

 except the cricothyroid; 3, bronchial to the bronchi and lungs; 

 4, oesophageal to the oesophagus, stomach, liver and solar plexus. 



Digitized by Microsoft® 



