/ 
) 
THE AXILLA. 1201 
fascia. The breast tissue, therefore, has a much wider distribution than was 
formerly supposed. Vertically, it extends from the second rib to the sixth costal 
cartilage at the angle where it begins to ascend towards the sternum ; horizontally, 
from a little within the lateral border of the sternum, opposite the fourth rib, to 
the fifth rib in the midaxillary line. The cnner hemisphere of the mamma rests 
-almost entirely on the pectoralis major; at its lowest part it slightly overlies the 
upper part of the aponeurosis covering the rectus abdominis muscle. The wpper 
quadrant of the outer hemisphere rests upon the greater pectoral, on the edge of 
the lesser pectoral, and to a slight extent on the serratus magnus, upon which 
it extends upwards into the axilla (“ axillary tail” of Spence) as high as the third 
rib, where it comes into relation with the thoracic group of axillary lymphatic 
glands. The remainder of the outer hemisphere rests almost entirely upon the 
serratus magnus, except the lowest part which overlaps the digitations of the 
external oblique arising from the fifth and sixth ribs. It follows, therefore, that 
fully one-third of the whole mamma lies inferior and external to the axillary 
border of the pectoralis major muscle. The surgeon must cut beyond the above 
limits if he wishes to remove the whole of the mammary tissue. 
The axillary fascia resists the spontaneous rupture of an axillary abscess, which, 
therefore, tends to spread upwards beneath the pectorals, and towards the root of the 
neck. To open the abscess the incision should be made upon the inner wall, behind, 
and parallel to, the long thoracic artery, which runs under cover of the anterior fold. 
Brachial artery Clavicle 
Biceps tendon Anterior axillary fold 
Supinator longus Coraco-brachialis Deltoid 
Biceps £ ae 
Flexor muscles 
Bicipital fascia 
Internal condyle 
Brachialis anticus 
Ulnar nerve 
Internal intermuscular septum | | 
Median nerve | 
Inner head of triceps 
Long head of triceps 
Lower border of teres major | 
Posterior axillary fold 
Fic. 809.—AxILLA, INNER ASPECT OF UPPER ARM AND ELBOW. 
The axillary lymphatic glands vary greatly in size and number ; many are no larger 
than a pin’s head. In the female some of them undergo an adipose functional involu- 
tion, whereby they come to resemble fat lobules. The central group (Leaf), embedded 
in the fat immediately beneath the axillary fascia, become inflamed in poisoned wounds of 
the upper extremity ; the pectoral group, related to the inner wall of the axilla and the 
long thoracic artery, are usually the first to become diseased in affections of the breast. 
In malignant disease of this organ the posterior (subscapular) and the apical (subclavicular) 
groups are generally affected, as are also, not infrequently, glands situated between the 
pectorales major and minor, and in the retro-pectoral fascia in the neighbourhood of the 
superior thoracic artery (Rotter). In health one or two glands can usually be felt by 
thrusting the fingers upwards and inwards beneath the anterior fold, the arm being only 
slightly abducted, so as not to stretch the axillary fascia. In clearing out the axilla for 
malignant disease, the surgeon removes all the lymphatic glands, and, as far as possible, 
all fat and fascia, including the sheath of the axillary vein. It must be remembered 
that the lower part of the axillary vein lies immediately underneath the deep fascia of 
the outer wall of the axilla; in cleaning the inner wall the long thoracic nerve must 
not be injured; and in removing the posterior group of lymphatic glands the long 
subscapular nerve, which accompanies the subscapular vessels, must be avoided, as it 
is doubly important to retain the action of the latissimus dorsi after removing the 
pectorals. ; 
76 
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