Secondly ; an anastomosis occurs beneath the acromion process and behind the glenoid cavity, between 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 inay 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 enjoy ed 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 mities are totally wanting, in w hich 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.
This fact is mentioned on Sir Charles Bell's authority, from whom we also quote the fol lowing short passage :—"We would do well to remember this double office of the scapula and its muscles, that whilst it is the very foundation of the bones of the upper extre mity, and never wanting in any animal that has the most remote resemblance to an arm, it is the centre and "point d'appui" of the muscles of respiration, and acts, in that capacity when there are no extremities at all.
Percussion and auscultation are constantly practised over the scapular region, the super ficial position of the spine of the scapula causing it to furnish satisfactory results when percussed, whilst the nature of the respiratory sound, in the subjacent portions of the lung, may be easily learned by applying the stetho scope to the supra- or infra-spinal fossa.
The scapular region is sometimes the seat of furuncular inflammation, and of anthrax, which selects in general the posterior aspect of the body, where the sub-cutaneous areolar tissue is most dense, often shows a special preference for the scapular region. Here likewise practical surgeons are well aware that chronic abscesses ("absees froid ") not un frequently occur.
Collections of matter in this situation are generally unconnected with any other local disease, but at the same time indicate consti tutional derangetnent, more or less profound. Chronic abscess in this locality is not always superficially seated ; it may have for its site the loose areolar tissue beneath the scapula, which connects the sub-scapularis to the ser ratus magnus muscle. Here it may attain a great magnitutle, and displace the scapula outwards to a considerable distance from the trunk.
Fractures of the body of the scapula are met with as the result of direct violence only, and occur less frequently than the slightness of the bone would lead one a priori to expect. The numerous muscles covering the bone, which form for it an elastic cushion, and its strong projecting spine, are sources of protec tion to which the scapula is indebted for its comparative immunity from this form of injury.
Ablation of large portions of the scapula, or even the complete removal of that bone with part of the clavicle, and the scapulo-humeral articulation, has been had recourse to in cases of extensive injury of the shoulder, as from gunshot wounds. (Larrey.) In the Htipital des Invalides at Paris may be still seen living examples of the success which sometimes attends even such severe mutilations; whilst the records of British sur gery also furnish successful instances of the complete removal of the scapula, scapular end of the clavicle, and upper extremity, for tumours of great magnitude occupying the region of the shoulder, of which the cases by Mr. Fergusson and the late Mr. Liston are amongst the most remarkable.
(B. Geo. 111‘Dowel.)