The Head and Neck. 239 



The two muscles are closely associated in the middle line. They 

 should be separated from one another and divided. 



(g) The sternothyreoideus. Origin: In common with the 

 sternohyoideus. Insertion : Lateral plate of the thyreoid 

 cartilage of the larynx. The muscle forms a thin band 

 lying on the side of the trachea. It is continued from the 

 thyreoid cartilage to the greater cornu of the hyoid as the 

 thyreohyoideus. 



(h) The trachea occupies a median position, and is supported by 

 cartilaginous tracheal rings. 



(i) The thyreoid cartilage of the larynx ; a saddle-shaped carti- 

 lage, composed of right and left thyreoid plates (Fig. 65). 



(j) The cricoid cartilage, a thick annular cartilage situated 

 between the thyreoid cartilage and the first tracheal ring. 

 It is connected ventrally with the thyreoid cartilage by the 

 cricothyreoideus muscle. 



(k) The deep cervical lymph gland (lymphoglandula cervicalis 

 profunda) is a large elongated reddish-colored gland in the 

 upper portion of the neck, opposite the thyreoid cartilage. 



(1) The thyreoid gland (gl. thyreoidea) lies on the ventral 

 surface of the trachea behind the cricoid cartilage. It is 

 composed of right and left portions connected across the 

 middle line by a thin median portion, the isthmus. 



(m) The common carotid artery (a. carotis communis) passes 

 forward from the superior thoracic aperture along the side 

 of the trachea. Its branches on the neck include the 

 superior thyreoid artery (a. thyreoidea superior), to the 

 thyreoid gland, and the (superior) laryngeal artery 

 (a. larnygea). The latter arises at the level of the thyreoid 

 plate, passing to the larnyx and to the sternohyoid sterno- 

 thryeoid muscles. 



(n) The internal jugular vein (v. jugularis interna) lies to the 

 lateral side of the common carotid artery, traversing the 

 neck from the jugular foramen of the skull to the superior 

 thoracic aperture. 



(o) The tenth cranial or vagus nerve (n. vagus) is the largest 

 of four nerves accompanying the carotid artery. It lies to 

 the lateral side of the common carotid, between the latter 



