THE SUBCLAVIAX ARTERY. 5<H 



the lower cervical transverse processes, it is inserted below, by a attach- 

 thin tendon about half an inch wide, into the second rib in front of m 

 the serratus posticus superior. 



Action. It acts as an elevator of the second rib ; and its fibres use - 

 having the same direction as those of the medius, it will help to 

 incline the ne-k in the same way. 



The SUBCLAVIAX ARTERY (fig. 213) is the first portion of the Subciavian 

 large trunk wliidi supplies the upper limb with blood, and is thus 

 designated from its position beneath the clavicle. On tJie right side, extends to 

 this vessel is derived from the bifurcation of the innominate upper hmb> 

 artery behind the sterno-clavicular articulation, and the part of it 

 named subclavian extends as far as the outer border of the first rib. 

 On the left side the artery arises in the thorax from the arch 

 of the aorta, and the first part therefore has a longer course, 

 and the special points in connection with the vessel will be mentioned 

 ifter a general description of the vessel in the neck has been 

 given. To reach the limb the artery crosses the lower part of 

 :he neck, taking an arched course over the top of the lung and the 

 first rib, and between the scaleni muscles. For the purpose of is divided 

 describing its numerous connections the vessel is divided into three 

 parts ; the first extending from the sterno-clavicular articulation to 

 inner border of the anterior scalenus ; the second, beneath the 

 scalenus ; and the third, from the outer border of that muscle to 

 outer edge of the first rib. 



FIRST PART. Internal to the anterior scalenus the artery lies First part, 

 deeply in the neck, and ascends somewhat from its origin. Between scalenus* 

 the vessel and the surface will be found the common tegumentary is dee P- 

 coverings with the platysma and the deep fascia ; the sterno- 

 nastoid, sterno-hyoid, and sterno-thyroid muscles ; and a strong in front of, 

 deep process of fascia from the inner border of the scalenus muscle. 

 Behind and below, it rests upon the pleura, which ascends into behind, and 

 lie arch formed by the vessel ; and the apex of the lung separates 

 -he artery from the vertebrae and the posterior ends of the first and 

 second rils. 



T'ef/is. The innominate vein lies below and rather in front of Veins with 

 this part of the artery. The internal jugular vein crosses the * 

 arterial trunk close to the scalenus ; and underneath this vein, 

 with the same direction, lies the vertebral vein. Much more 

 superficial, and separated from the artery by muscles, is the deep 

 part of the anterior jugular vein. 



Xf- )-$. In front of the artery lies the pneumo-gastric nerve, near Position of 

 to the internal jugular vein ; and inside this, the lower cardiac n 

 branch of the same nerve trunk. Beneath the subclavian artery on 

 the right side winds the recurrent branch of the pneumo-gastric ; 

 and one or two branches of the sympathetic nerve form loops round 

 the vessel. 



SECOND PART. Beneath the scalenus the vessel is not so deep as in Second part 

 the first part of its course, and at this spot it rises highest above the scaiSms 

 clavicle. It is covered by the integuments, platysma, and deep In front) 

 fascia : then by the clavicular origin of the sterno-mastoid ; and 



