MUSCLES OF RIGHT SIDE OF TRUNK AND HEAD 93 



Ductless Glands : The available endocrine glands of the 

 cervical region are limited to the thyroid and parathyroids. 



The thyroid gland is the only ductless gland required to be 

 dissected at this time. This is a large bilobed gland with each 

 lobe lying on the lateral side of the trachea, just caudad to the 

 larynx. The two lobes are connected by an isthmus which 

 passes over the ventral side of the trachea and connects the two 

 lobes of the thyroid gland at the caudal ends and lies dorsad to 

 the sternohyoid muscle (62). 



The parathyroid glands are four small bodies more or less 

 imbedded in the medial border, one at either end, of the two 

 lobes of the thyroid gland. They will probably be quite 

 invisible except in sectioned tissue. 



The pineal body and pituitary gland are described in Chapter 

 XII, B. 



D. VEINS AND ARTERIES OF THE HEAD AND NECK 



(Fig. 26, 27) 



Method: Clear the skin and subcutaneous muscle (platysma) 

 away, but do not remove the skin entirely from the head unless 

 it is found to be absolutely necessary, for this region must be kept 

 from dessicating until the work in Chapter XII is completed. 

 The student should locate the large vessels of the neck, on that 

 side of the neck which was not mutilated by the preparator 

 when he injected the arterial system, and dissect craniad. 



The external jugular vein (Fig. 27, EJ) is readily seen after 

 the superficial fascia and platysma muscle have been removed. 

 It receives two important branches from the head, the anterior 

 facial, which drains the suborbital, maxillary and mandibular 

 regions and the posterior facial, which drains the temporal, 

 and occipital regions of the head. The external jugulars are 

 joined together by an anastomosing branch, the transverse 

 jugular, which is sometimes nearly as large as either of the 

 external jugulars. After the external jugular vein has been 

 exposed, the operator may proceed safely with the dissection. 



