THE NECK, ANTERIOR. 115 



and sometimes the thyroidea ima from the arch of the aorta 

 or the innominate artery. 



Veins : Superior, middle, and inferior thyroid ; the first 

 two empty into the internal jugular, the last two into the 

 innominate. 



Nerves : From the middle and inferior cervical ganglia. 



Lymphatics : Pass to the right lymphatic and the tho- 

 racic ducts. 



Muscles : The thyroid gland is at times found to be 

 connected to the hyoid bone by a detached slip of the 

 thyrohyoid muscle, which is called the levator glandulae 

 thyroideae. 



Ligaments : The gland is retained in its position against 

 the trachea and larynx by the third layer of cervical fascia 

 (see page 139), which forms a capsule for the gland and 

 encloses all these structures. 



The student should prepare himself upon the trachea, 

 thoracic duct, and brachial plexus. The description of 

 these structures is omitted here, but is given, trachea, p. 

 356; thoracic duct, p. 344, and brachial plexus, p. 312. 



DISSECTION OF THE DEEP FACE AND PHARYNX. 



The plan of dissection is determined by whether the skull is to be pre- 

 served for future use or not. If it is desirable to save the skull intact, the first 

 plan can be adhered to, if otherwise, the second. 



The first plan : 



Sever the attachment of the masseter muscle close to the zygomatic arch, 

 draw it downward and carefully cut it away from its insertion. In doing 

 this recognize and save the masseteric nerve and artery, which reach the muscle 

 through the sigmoid notch in the lower jaw. Then remove the masseter 

 entirely. 



Cut the temporal muscle from its insertion into the coronoid process, keep- 

 ing close to the bone. When the insertion is cut through, draw the tendon 

 upward through the zygomatic arch, sever the muscular attachment to the 

 temporal fossa, saving the deep temporal nerves and arteries, and remove the 

 muscle entirely. (In the preceding plan the skull-cap has not been removed. ) 



