The H]' ad and Nkck. 163 



of the occipital bone. Insertion: Tip of the greater cornu 

 of the hyoid. The muscle has been divided. 



The superficial temporal and internal maxillary arteries should be 

 divided. 



(b) The styloglossus. Origin: Jugular process. Insertion: 

 The muscle passes downward and forward, expanding at the 

 base of the. tongue into a broad sheet the fibres of which 

 extend to its anterior tip. 



The muscle should be carefully separated from two others on its 

 medial side and divided. 



(c) The stylohyoideus minor. Origin : Jugular process. In- 

 sertion: Lesser cornu of the hyoid. A slender muscle lying 

 to the medial side of the styloglossus. 



The remaining muscle is the stylopharyngeus, the insertion of which 

 is on the lateral wall of the pharynx. 



(d) The geniohyoideus. Origin : Mandibular symphysis. In- 

 sertion : Anterior surface of the body of the hyoid: impaired. 



(e) The genioglossus. Origin: Medial surface of the mandible 

 immediately behind the symphysis. The fibres pass upward 

 and slightly backward into the substance of the tongue. 



(f) The hyoglossus. Origin : The body of the hyoid and the 

 greater and lesser cornua by more or less separate heads. 

 The muscle passes into the base of the tongue enclosed on 

 either side by the styloglossi. 



(g) The lingualis, or intrinsic muscle of the tongue consists of a 

 mass of fibres with no skeletal attachments. 



(h) The lingual nerve (n. lingualis), one of the chief branches of 

 the mandibular, passes forward and downward to the side of 

 the tongue and enters its substance immediately below the 

 ventral border of the styloglossus. The lingual is the 

 sensory nerve of the tongue. Near its point of origin the 

 lingual nerve receives the chorda tympani (p. 171). 



(i) The twelfth cranial or hypoglossal nerve (n. hypoglossus) 

 enters the base of the tongue. It lies on the lateral side of 

 the external carotid artery and on the medial side of the 

 stylohyoideus major. It is distributed as a motor nerve to 

 the lingual muscles. 



(j) The ramus lingualis of the ninth cranial, or glossopharyngeal 

 nerve (n. glossopharyngeus) enters the base of the tongue 

 at a point dorsal to the hypoglossus and between the stylo- 

 hyoideus minor and the stylopharyngeus. It is a gustatory 

 nerve of the tongue. 



8. Dissection of the e^tra-cranial roots of the ninth to twelfth nerves. 



These nerves, which for the most part have already been exposed, 

 may be traced to their origin in the jugular foramen. The tympanic 

 bulla should be exposed by removing whatever portions of the parotid 

 gland are still in place. The lingual and hypoglossal nerves may be 



