SCAPULAR REGION. 



435 



The supra-scapular artery (sometimes de- 

 signated artcriu transversalis humeri) has 

 elsewhere been described as arising from the 

 thyroid axis of the subclavian trunk ; it passes 

 at first downwards, and then nearly trans- 

 versely outwards, anterior to the phrenic 

 nerve, and between the sterno-cleido mastoid 

 and the anterior scalenus muscles ; it next 

 runs along the base of the supra-clavicular 

 triangle in close contact with the front of the 

 subclavian vein, behind the clavicle and sub- 

 clavian muscle, and below the level of the 

 subclavian artery, here in the third stage ; 

 more externally it crosses this great trunk 

 near the commencement of the axillary ; it 

 then passes in front of the brachial plexus of 

 nerves, running along with the supra-scapular 

 branch, parallel to the omo-hyoid, and covered 

 by the trapezius muscle, to the superior costa 

 of the scapula, where it enters the supra- 

 spinal fossa above " the ligament of the 

 notch." Whilst under cover of the trapezius 

 muscle, the supra-scapular artery gives off a 

 large muscular branch, the ramifications of 

 which have been alluded to as assisting to form 

 the acromial anastomosis. The final distri- 

 bution of the artery is by two branches. 



1. The supra-spinal branch, which is distri- 

 buted to the supra-spinatus muscle, and which 

 anastomoses near the posterior superior angle 

 of the scapula, with branches from the pos- 

 terior scapular arterv. 



2. The infra-spinal branch, which enters the 

 infra-spinal fossa by passing beneath the 

 acromion process, and the " spino-glenoid 

 ligament" of Sir Astley Cooper; here it is 

 distributed to the deep surfaces of the muscles 

 of this region, and anastomoses freely with the 

 termination of the posterior scapular, and with 

 the posterior branch of the subscapular 

 arteries. 



The structures thus shown to be contained 

 in the supra-spinal division of the scapular 

 region are the following : 1. Integument, 

 dense areolar tissue, and superficial nerves ; 

 2. A thin aponeurosis covering, 3. The 

 trapezius muscle ; 4. A layer of fatty areolar 

 tissue; 5. The strong supra-spinal aponeu- 

 rosis; 6. The supra-spinatus muscle ; 7. The 

 supra-scapular vessels and nerve ; 8. The 

 smooth concave surface of the bone (fossa 

 supra-spinata). 



Below the spine of the scapula portions of 

 the trapezius, deltoid, and latissimus dorsi 

 muscles overlap the scapular region, and 

 partly conceal from view the intrinsic muscles 

 of the infra-spinal fossa. These muscles are 

 covered by an aponeurotic expansion, which 

 is thin over the trapezius and latissimus dorsi 

 muscles ; more dense and strong where it 

 covers that part of the deltoid which belongs 

 to the region of the shoulder ; and much 

 stronger still, where it invests the infra-spi- 

 natus and teretes muscles ; superiorly, it is 

 attached to the lower edge of the spine of the 

 scapula ; posteriorly, it is connected with the 

 tendinous expansion of the trapezius muscle, 

 and the base of the scapula. From its deep 

 surface, septa are detached, which pass in 



between the subjacent muscles, and contract 

 firm adhesions to the bone ; whilst, at the 

 posterior edge of the deltoid muscle, it divides 

 into two lamina?, between which that muscle 

 is enclosed ; the superficial layer covers the 

 outer surface of the deltoid, and so becomes 

 identified with the fascia of the arm ; whilst 

 the deeper layer, passing beneath the deltoid 

 muscle, becomes continoous with the capsule 

 of the scapulo-humeral articulation. 



The trapezius and latissimus dorsi muscles 

 overlap the one, the posterior superior, the 

 other, the inferior angle of the scapula. The 

 trapezius is tendinous where it glides upwards 

 and forwards over the. smooth triangular sur- 

 face situated behind the spine of the scapula. 

 A bursa here intervenes between the bone and 

 the flat tendinous expansion of the muscle. 

 The latissimus dorsi, by its fleshy fibres, over- 

 laps the inferior angle of the scapula. The di- 

 rection of the muscle at this part of its course 

 is nearly horizontal. As these fibres pass off 

 the scapula, they are joined by those of its 

 costal origin, and thence they all run upwards 

 and forwards, presenting a twisted appearance 

 to their insertion, which takes place by a 

 narrow flat tendon into the bottom of the bi- 

 cipital groove of the humerus. Both these 

 muscles, from their peculiar relation to the 

 scapula, serve to compress it against the 

 thorax, and so to prevent its being unduly 

 separated from the trunk in the varied and 

 extensive movements which it enjoys. 



A peculiar displacement of the scapula, the 

 result of accident, has been described by Vel- 

 peau, who supposes it to depend on paralj'sis 

 of the serratus-magnus from injury of the 

 great posterior thoracic nerve (external respi- 

 ratory, Ch. Bell), which is distributed to that 

 muscle. The appearances observed in the 

 case detailed by Velpeau were, remarkable 

 projection backwards of the scapula, especially 

 of its posterior border, and inability on the 

 part of the patient to bring it in contact with 

 the side of the thorax : cases corresponding 

 in their general features to this description 

 have been seen by almost every surgeon. In 

 those which have occurred in the writer's ex- 

 perience, the projection of the posterior edge 

 and of the lower angle of the scapula was 

 very remarkable, and the movements of the 

 upper extremity were greatly impeded. Mr. 

 Adams has suggested, as a more plausible ex- 

 planation of the deformity in these cases, that 

 the lower angle of the scapula escapes from 

 under the latissimus dorsi muscle; an accident 

 which may occur from too great elevation and 

 abduction of the upper extremity ; and the 

 more easily, as, in the majority of instances, 

 either the muscle is not attached to the bone 

 at all, or else it adheres to it by a few small 

 fibres only. 



The deltoid, trapezius, and latissimus dorsi 

 muscles, where they overlap the scapular re- 

 gion, circumscribe a triangular space, in which 

 may be seen part of the posterior edge of the 

 scapula, with the attachment to it of the 

 rhomboid muscle, and also a portion of the 

 infra-spin;Uus and of the teres minor muscles. 



F F 2 



