THE HEAD AND NECK. 



53 



THE MUSCLES AND NERVES IN THE SECOND LAYER OF DEEP CERVICAL FASCIA. 



1 . The sterno-hyoid and omo-Jiyoid. 



2. The sterno-thyroid and thyro-hyoid. 



3. The nerve-supply of these the ansa liypoglossal loop. (Figs. 23 and 29.) 

 Having turned the sterno-mastoid muscle and the fascia extending from it to 



the mid-line of the neck aside, you expose the sterno-hyoid and the omo-hyoid 

 of this group. Figure 27 shows you the insertion of these two muscles con- 

 jointly into the lower border of the body of the hyoid bone. Cut these two 

 muscles one inch below this insertion, turn the lower part of the same forward 

 carefully, and note the nerve-supply. These muscles must be handled very care- 

 fully, in order to preserve them and also their nerves. The omo-hyoid arises 

 from the superior border of the scapula for one inch. The sterno-hyoid arises 



Facial artery 



Lingual artery 



Supra-hyoid branch 

 Infra-hyoid branch 



Superior laryngeal branch 



Crico-thyroid branch 



External carotid artery 



Ascending pharyngeal artery 



Internal carotid artery 



Sterno-mastoid branch 



Superior thyroid artery 



Common carotid artery 



Inferior thyroid artery 



FIG. 28. SCHEME OF SUPERIOR THYROID ARTERY. 



from the manubrium sterni. Trace out these origins at a later stage of your 

 work. 



The sterno-cleido-thyroid is commonly called sterno-thyroid. This is inserted 

 into the oblique line of the ala of the thyroid cartilage. (Fig. 27.) From here 

 it is continued to the lower border of the outer third body, and the inner half of 

 the greater horn of the hyoid bone as the thyro-hyoid muscle. 



The sterno-thyroid arises from the manubrium low down, and also from the 

 clavicle. (Fig. 30.) Detach this muscle from its insertion and turn it down 

 very carefully, and you will see the thyroid gland and its isthmus. 



The thyro-hyoid removed by detaching it at its origin, you expose the thyro- 

 hyoid membrane, and see entering the same the superior laryngeal nerve and 

 artery. (Fig. 28.) 



