QUESTIONS AND ANSWERS 135 



State the function of the eighth pair of cranial nerves. 



(Auditory.) Sense of hearing and maintenance of equilibrium 

 through its connection with the semicircular canals. 



What is the function of the glossopharyngeal nerve? 



(Ninth pair of cranial nerves. ) This is a mixed nerve ; it sup- 

 plies motor power to the muscles of the pharynx and sensory fibres 

 to the posterior third of the tongue, the soft palate, part of the 

 pharynx, and the anterior surface of the epiglottis. It is princi- 

 pally concerned in deglutition and the sense of taste on the posterior 

 third of the tongue. 



State the function of the pneumogastric, or vagus, nerve. 



(Tenth pair of cranial nerves.) It supplies sensation to the ex- 

 ternal ear, pharynx, oesophagus, stomach and respiratory passages ; 

 and motor power to the muscles of the pharynx, larynx, trachea, 

 bronchi, oesophagus, stomach and intestines. 



It is the inhibitory nerve of the heart and contains vasomotor 

 fibres for the lungs and trophic fibres for the lungs and heart. 



What is the function of the eleventh pair of cranial nerves? 



(Spinal accessory.) Motor nerve .to the sternomaxillaris, mas- 

 toidohumeralis, and the cervical and dorsal trapezius muscles. By 

 giving motor fibres to the vagus, it has some control over the larynx 

 and voice. 



State the function of the great hypoglossal nerve. 



(Twelfth cranial pair.) Motor nerve to the tongue. 



What nerves, afferent and motor, supply the larynx? 



Superior laryngeal branch of the vagus is the afferent or sen- 

 sory nerve. It also supplies motor fibres to the cricothyroid muscle. 

 The inferior laryngeal, or recurrent, branch of the vagus supplies 

 all the muscles of the larynx, except the cricothyroid, with motor 

 power. 

 What sjmiptoms would ensue in case of a transverse section of the 

 motor nerve supplying the arytenoid muscles on one side? 

 Inspiratory dyspnoea, accompanied by a roaring or whistling 

 sound due to paralysis of the muscles moving the vocal cord. The 

 cord would hang free in the larynx obstructing the air current. 

 Paralysis of this kind produces the disease called "roaring." 



What are the functions of the sympathetic nervous system? 



The sympathetic nervous system supplies vasodilator and vaso- 

 constrictor fibres to the blood-vessels, the viscera with motor and 

 inhibitory fibres, accelerator fibres to the heart, dilator fibres to the 



