1572 A MANUAL OF ANATOMY 



During the present stage of the dissection the facial vein is to be kept in view ; 

 its union with the anterior division of the temporo-maxillary vein to form 

 the common facial vein is to be shown ; and the ending of the common facial 

 vein and of the lingual veins in the internal jugular are to be displayed. 



The posterior branches of the external carotid, namely, the occipital and 

 the posterior auricular, are also to be fully dissected, and as many of their 

 branches as possible shown. The ascending pharyngeal branch of the 

 external carotid artery is placed too deeply for complete dissection at this 

 stage, but the dissector should bear in mind that it arises from the deep 

 surface of the external carotid near its commencement, and he may expose 

 it by separating the external and internal carotid arteries. The terminal 

 branches of the external carotid, namely, the superficial temporal and the 

 internal maxillary, will be dissected at a later stage in connection with the 

 parotid gland. 



At this stage the dissector should direct his attention to the thyroid body. 

 This should be dissected with the greatest care, its lateral lobes and isthmus 

 being clearly defined, together with their blood -supply, the inferior thyroid 

 artery reaching the lateral lobe from below. The not infrequent presence 

 of a pyramidal or middle lobe is to be borne in mind, and in connection with 

 it the fibrous band and levator glandulae thyroidese muscle, which pass from 

 its apex to the body of the hyoid bone. When present, it usually springs 

 from the upper border of the isthmus close to the left lobe. The disposition 

 of the thyroid veins is to be noted. The cervical parts of the trachea and 

 oesophagus are also to be fully dissected. The manner in, and the extent to, 

 which the oesophagus projects to the left of the trachea at the root of the 

 neck is to be specially noted, and the inferior or recurrent lar5aigeal nerve 

 and inferior laryngeal artery are to be carefully displayed as they ascend in 

 the groove between the trachea and oesophagus. 



Root of the Neck. — The deep dissection of the root of the neck is now to 

 be overtaken. The scalene muscles — anticus, medius, and posticus — are to 

 be dissected, and their relations are to be carefully noted, more especially 

 those of the scalenus anticus, in connection with which the scalene tubercle 

 or spine (Lisfranc's tubercle) on the inner border of the first rib is to be 

 examined. The first part of the subclavian artery is to be dissected, and 

 its relations mzistered. The junction of the internal jugular and subclavian 

 veins to form the innominate vein on either side is to be shown. Opening 

 into the angle of junction of these two veins on the right side the short right 

 lymphatic duct is to be looked for, and on the left side the thoracic duct, 

 the latter arching outwards, forwards, and downwards. The left subclavian 

 artery and the left common carotid at the root of the neck are to be con- 

 trasted with the corresponding vessels of the right side, and the differences 

 noted, not only as regards their origins, but also as regards their relations. 

 The right pneumogastric nerve is to be shown crossing the first part of the 

 right subclavian artery, and parting with its recurrent laryngeal branch 

 opposite the lower border of the vessel, that branch turning up behind the 

 artery. The left pneumogastric nerve will be found parallel with the first 



Eart of the left subclavian artery, its recurrent laryngeal branch having 

 een given off within the thorax, opposite the lower border of the arch of the 

 aorta. The recurrent laryngeal nerve on either side is] then to be fol- 

 lowed upwards in the groove between the trachea and oesophagus, in com- 

 pany with the inferior laryngeal artery. The sympathetic loop, known as 

 the ansa Vieussenii, is to be shown in connection with the first part of the 

 subclavian artery, and the sympathetic cord will be found behind it. The 

 branches of this paxt of the vessel cire now to be dissected. The vertebral 

 artery is to be dissected in the first part of its course, and the inferior cervical 

 ganglion of the sympathetic, which lies behind it, is to be kept in view. The 

 mode of termination of the vertebral vein is to be shown. The internal mam- 

 mary artery is to be followed downwards as far as its entrance upon its thoracic 

 course, and the phrenic nerve is to be shown crossing it superficially from 

 without inwards. The thyroid axis is next to receive attention, and its three 

 branches, namely, inferior thyroid, transverse cervical, and suprascapular. 



