22 



The Bones of the Head 



genio-hyoid, genio-hyo-glossus, and also by the external pterygoic 

 It is elevated by the masseter, temporal and internal pterygoid ; 



advanced by the 

 pterygoids and the 

 superficial part of the 

 masseter ; and re- 

 tracted by the deep 

 part of that muscle 

 and the temporal. 

 The pterygoids im- 

 part the lateral move- 

 ments. 



Relations of the 

 articulation exter- 

 nally are skin, fasciae, 

 and some of the pa- 

 rotid gland, but the 

 movements of the 

 condyle are readily 

 followed from the ex- 

 terior. Behind are the external auditory meatus, some of the parotid 

 gland, and the external carotid and its terminal divisions. Close above 

 and behind are the tympanum and the internal ear. 



Permanent closure of the jaws may demand resection of the 

 condyle ; this is accomplished by making an incision along the lower 

 border of the zygoma, beginning over and through the posterior 

 border of the masseter, and continuing it back to the tragus. The 

 raspatory then thrusts down the branches of the facial nerve, part 

 of the parotid gland, and other tissues which hide the condyle ; the 

 neck of the condyle is then cut with a fine saw and drawn out with 

 some of the insertion of the external pterygoid, and perhaps with the 

 inter-articular fibro-cartilage. 



Eminentiaa 

 2, condyle ; 

 cartilage. 



THE ARTERIES OF THE HEAD AND NECK 



The common carotid artery springs on the right side from the 

 division of the innominate, but on the left side it ascends from the 

 transverse part of the arch of the aorta. 



Up to the level of the sterno-clavicular joint the left artery has 

 exceptional relations, but from this point to the upper border of the 

 thyroid cartilage, where the common carotids divide, the relations are 

 similar on the two sides. 



The tboracic portion of the left carotid springs from the 

 transverse aorta, between the innominate artery and the left sub- 



