SCAPULAR REGION. 



437 



clavian, external to the scaleni muscles, an 

 irregularity which is by no means uncommon. 

 When derived from its more usual source, this 

 branch runs transversely across the scalenus 

 anticus muscle and the phrenic nerve, 

 covered by the clavicular portion of thesterno- 

 cleido-mastoid muscle : it then traverses the 

 apex of the supra-clavicular triangle, lying 

 above the level of the curve of the subclavian 

 artery, and placed before or between the for- 

 mative roots of the brachial plexus ; passing 

 still further outwards it gets under the trapezius 

 muscle, and here gives off its ascending cer- 

 vical branch ; at the posterior superior angle 

 of the scapula, the artery bends backwards, 

 under cover of the levator angnli scapula ; 

 here it changes its direction, and inclining 

 downwards, runs along the vertebral edge of 

 the scapula. Its course may, therefore, be 

 divided into two stages ; the first extends 

 from the origin of the artery to the superior 

 angle of the scapula, and so far its direction 

 is nearly horizontal, and it is properly desig- 

 nated the " arteria transversalis colli." In 

 its second stage, the artery runs vertically, 

 parallel to, and about an inch distant from, 

 the vertebral margin of the bone. This portion 

 of the artery, which alone should be termed 

 " posterior scapular," is covered by the great- 

 er and the lesser rhomboid muscles, and by 

 the trapezius. To these, and to the other 

 muscles attached to the scapula, it furnishes 

 numerous branches, and at the inferior angle 

 of that bone, it anastomoses very freely with 

 the posterior branch of the sub-scapular 

 artery. 



The structures which occupy the infra- 

 spinal fossa may here be briefly recapitulated : 

 first the integument and the sub-cutaneous 

 layer of areolar tissue ; secondly, the fleshy 

 edges of the deltoid and the latissimus dorsi 

 muscles, and the triangular tendinous expansion 

 of the trapezius, covered by their respective 

 portions of fascia: in the interval between 

 these muscles, and partly covered by them, 

 lie, thirdly, the infra-spinatus, the teres major, 

 and the teres minor, muscles ; these are con- 

 tained in distinct sheaths, formed by their 

 investing fascia, and the aponeurotic septa 

 detached from its deep surface ; fourthly, the 

 anastomoses of branches from all the scapular 

 arteries; fifthly, the bone (fossa infra-spinata). 



Around the margins of the scapula there 

 exists, as has thus been shown, a chain of 

 large blood-vessels, which, by numerous 

 branches, anastomose freely at the angles, 

 and on the different aspects of the bone, 

 forming a vascular circle of great interest to 

 the surgeon ; for by means of it the upper 

 extremity is mainly supplied with blood, when 

 the current through the subclavian is inter- 

 rupted, at the distal side of the branches 

 which spring from its first stage. At the 

 acromial end of the scapula two series of 

 anastomoses may be observed ; the first, su- 

 perficial to the acromion process, is formed 

 by the union of the superior acromial branches 

 of the supra-scapular artery with the ascending 

 (inferior acromial) branches of the circum- 



flex, and with the acromial thoracic divisions 

 of the axillary artery. 



Secondly; an anastomosis occurs beneath 

 the acromion process and behind the glenoid 

 cavity, bet ween the supra- and the sub-scapular 

 arteries. 



Thirdly ; at the posterior angle of the scapula, 

 the supra- and the posterior scapular arteries 

 anastomose, in the posterior part of the supra- 

 spinous fossa. 



Lastly ; at the inferior angle, a free commu- 

 nication exists under cover of the infra-spina- 

 tus muscle, between the supra-, the posterior, 

 and the sub-scapular branches, aided by the 

 posterior circumflex. 



Through all these channels the sub-clavian 

 and the axillary trunks communicate with 

 each other, and experience has shown that 

 full reliance may be placed on the capability 

 of this anastomosis to maintain the circula- 

 tion in the upper extremity after a ligature 

 has been placed on the subclavian artery in 

 the second or third stage. 



The veins of the scapular region merit no 

 particular description ; they are very numer- 

 ous, and communicate freely with each other. 

 They accurately follow the course of the 

 arteries. Those which lie above the spine of 

 the scapula form one or two trunks of con- 

 siderable size, which accompany the supra- 

 scapular artery, and unite with the subclavian 

 vein, external to the scalenus muscle; those of 

 the infra-spinal fossa constitute a very large 

 trunk, the sub-scapular vein, which enters the 

 axilla and joins the axillary vein, as it lies on 

 the posterior wall of the axilla; the sub-scapu- 

 lar vein here forms an important anterior 

 relation to its accompanying artery. 



The lymphatics of the scapular region are 

 arranged in two sets ; the superficial which 

 pass to the ganglia of the axilla, and a deep 

 set which closely correspond to the course of 

 the bloodvessels, and terminate, as do the 

 venous trunks,. in the supra-clavicular and in 

 the axillary regions. 



The scapular region participates in the 

 remarkable mobility of the bone which sup- 

 ports it, but as its motions cannot be regarded 

 independently of those of the shoulder joint, 

 we refer to the article on that subject for their 

 elucidation. 



The uses of the scapula may be briefly 

 stated as follows: In the first place it con- 

 nects the upper extremity to the trunk, and 

 participates in, and is subservient to, many of 

 the movements enjoyed by the upper extremity. 

 Secondly, it furnishes, by its flat surface, a 

 lateral protection to that portion of the thorax 

 against which it is applied. Thirdly, it is 

 concerned in the mechanism of respiration, 

 furnishing processes and surfaces for the 

 attachment of numerous muscles, which are 

 capable of altering the capacity of the thorax, 

 This latter function of the scapula is well 

 illustrated by cases where the upper extre* 

 unities are totally wanting, in which the mus- 

 cles, passing from the scapula to the thorax 

 are well-developed, and act with vigour in 

 effecting the full expansion of the thorax. 



F F ;i 



