TRACHEA AND CESOPHAGUS 231 



lobe of the thyreoid gland lie upon each side of it, the lobe 

 of the gland being closely applied to its upper part. A 

 recurrent nerve ascends, on each side, in the angle between 

 the trachea and oesophagus. 



The oesophagus or gullet is a narrow tube, with thick 

 muscular walls, which extends from the pharynx to the 

 stomach. In the cervical part of its course it lies between the 

 trachea and the longus colli muscles, and as it descends 

 it inclines slightly to the left, so that it comes more closely 

 into relation with the lobe of the thyreoid gland and the 

 carotid sheath upon the left side than with the same structures 

 on the opposite side (Figs. 54, 83, 108, 109). 



The dissector may terminate his dissection of the neck by 

 an examination of the scalene muscles and the rectus capitis 

 lateralis muscle. 



SCALENE MUSCLES AND RECTUS LATERALIS. 



Musculi Scaleni. The scalene muscles constitute the fleshy 

 mass which is seen extending from the transverse processes 

 of the cervical vertebrae to the upper two costal arches. 

 They are three in number, and are named, from their relative 

 positions, anterior^ medius, and posterior. 



Musculus Scalenus Anterior, The scalenus anterior is a 

 well-defined muscle which is separated from the scalenus 

 medius by the roots of the brachial plexus and the subclavian 

 artery. It arises from the anterior tubercles of the transverse 

 processes of the third, fourth, fifth and sixth cervical vertebrae, 

 and, tapering somewhat as it descends, it is inserted into the 

 scalene tubercle on the inner margin of the first rib, and 

 also into the superior surface of the same bone between the 

 grooves for the subclavian artery and vein (Fig. 84). 



The upper part of its anterior surface is concealed by the 

 sterno-mastoid, and the lower part by the clavicle. The 

 common carotid artery ascends along its medial border. 

 Between it and the sterno-mastoid lie (i) the internal jugular 

 vein; (2) the intermediate tendon of the omo-hyoid ; (3) the 

 phrenic nerve, passing downwards and forwards ; and (4) the 

 transverse cervical and transverse scapular arteries, passing 

 backwards and laterally, superficial to the phrenic nerve. 

 Between it and the clavicle lies the subclavian vein. 



Its posterior surface is in relation, above, with the tips of 



