362 



AXILLA. 



the ribs, intercostal muscles, and serratus pos- 

 ticus superior. 



The posterior wall of the axilla is formed by 

 the subscapular muscle, the tercs major and 

 the latissimus dorsi. to which the long head of 

 the triceps may be added. Along the inferior 

 margin of the subscapular muscle, the subsca- 

 pular artery runs. This is a vessel of considerable 

 size, and deserves the attention of the surgeon. 

 It arises from the axillary artery at the tendon of 

 the subscapular muscle, and passes all along 

 the inferior or anterior edge of this muscle to 

 the inferior angle of the scapula, where it ter- 

 minates by branches which supply the muscles 

 connected with thai point. The teres major is a 

 long, flat muscle, strap-shaped, one inch and 

 a half or two inches in breadth, extending from 

 the inferior angle of the scapula, to the poste- 

 rior margin of the bicipital groove of the hu- 

 merus. Its lower edge is in part covered 

 by the latissimus dorsi and then by the inte- 

 guments, and forms, principally, the poste- 

 rior fold of the axilla. The posterior surface is 

 covered by the latissimus, nearer the arm by 

 the integuments, and then by the long- head of 

 the triceps and the humerus. Its anterior sur- 

 face corresponds to the subscapular, latissimus, 

 coraco-brachiahs, biceps, and the axillary ves- 

 sels and nerves. 



The latissimus dorsi forms a very small part 

 of the axilla ; we see it passing over the inferior 

 angle of the scapula and twisting round the 

 teres major, so that its posterior surface be- 

 comes anterior, and the tendon in which it 

 ends gets internal to that of the teres. Its 

 edge does not go quite so low as that of the teres 

 major, but, except there, it prevents that muscle 

 from touching the axillary vessels. It is some- 

 times connected to the great pectoral by a. fleshy 

 slip which passes across the axilla. 



The axilla has all the conditions which ex- 

 pose a part to frequent disease ; a position 

 which puts it in the way of many external 

 injuries ; an important joint closely related 

 to it ; bones, liable to fracture ; arteries, veins, 

 and nerves of great size ; numerous lymphatic 

 glands, connected with tha most delicate parts 

 of the body, lying in it; and then a quantity 

 of cellular tissue, loose, vascular, and con- 

 stantly undergoing alterations. 



To the observations made on these points 

 in the course of the present article, we shall 

 now make a few additions. 



Wounds penetrating into the axilla endanger 

 the nerves, artery, and vein, if inflicted near 

 the humerus below, or close to the clavicle 

 above. In the latter situation, as mentioned 

 before, they may give rise to aneurismal varix. 

 At the lower margin of the anterior wall the 

 external mammary artery may be injured, and 

 along the inferior border of the posterior wall 

 the .subscapular vessels lie exposed. 



The shoulder- joint is more liable to disloca- 

 tion than any other in the body, and in most 

 cases tho head of the humerus comes into the 

 axilla. The great vessels and nerves are dis- 

 placed inwards, the circumflex vessels and 

 nerve often torn. The head of the humerus 



lies just below the subscapular muscle, and 

 forms a tumour in the axilla easily felt from 

 below. (See SHOULDER, ARTICULATIONS. OF 

 THE.) 



The neck of the humerus is often broken 

 above the insertion of the arm-pit muscles. 

 The lower fragment is drawn inwards by them 

 and L>p\vards by the deltoid, whilst the supra- 

 spinatus directs the upper fragment out. In 

 this state of things the rough extremity of the 

 lower piece irritates, perhaps lacerates the ves- 

 sels and nerves, and if not properly managed 

 leaver a permanent osseous tumour in the axilla. 



Collections of matter are very frequently 

 met with in the axilla. These occur either 

 about inflamed glands, or in the cellular tissue 

 connected with these glands, or they may have 

 found their way into this region, their focus 

 being somewhere else. The abundance of cel- 

 lular membrane here, its vascularity, its in- 

 cessant movements, and the dragging and 

 stretching to which it is exposed, render it 

 very liable to formations of pus. Irritation 

 of the delicate integuments may occasion them, 

 and they may be formed in the neck and pass 

 into this region through the opening at its 

 apex. The looseness of the texture is such 

 as to allow suppurations to go on to a great 

 extent, whilst the movement of the walls pre- 

 disposes to their termination in sinuses. 



The absorbent glands, however, are the or- 

 gans which most frequently take on disease 

 in this place. These may become inflamed 

 and enlarged from sympathy with disease or 

 injury in any part of tho corresponding limb, 

 the back, the c urface of th-2 thorax, or the upper 

 part of the abdomen. When inflamed, they 

 often run on to suppuration, or resolution may 

 follow on the removal of the exciting cause. 

 Slight lesions of the skin of the parts men- 

 tioned may determine the formation of ab- 

 scesses, as a scratch on the finger, a blister on 

 the chest, &c. Paronychia is not an unusual 

 exciting cause. 



Formidable inflammations of these glands, 

 often attended with fatal consequences, follow 

 the absorption of poisons. The cases most 

 familiar to us in this country arise from wounds 

 received in dissecting. The glands seem to 

 arrest the poison in its progress to the circu- 

 lation. They become excited and congested. 

 The cellular tissue surrounding, imbedding, 

 and partly forming them, inflames ; a puffy 

 swelling marks the effusion of serum into the 

 cellular membrane, which may or may not be 

 followed by suppuration. 



The glands frequently take on the disease 

 under which the neighbouring mamma labours, 

 as cancer, fungus hcematodes, &c. These 

 must be removed if the breast be amputated. 

 They are generally in the course of the external 

 mammary artery, and no other vessel is in- 

 terested in their removal, yet the looseness of 

 the tissue in which they lie renders it unsafe to 

 cut the little vessels derived from this incon- 

 siderable artery. Surgeons usually twist or 

 tear away the glands, or else apply a ligature 

 to the vessel before they cut it. 



