1200 SURFACE AND SURGICAL ANATOMY. 
1 in. external to and a little below the level of the tip of the coracoid process. In 
examining the upper end of the humerus for fracture, the tuberosities should be 
orasped between the finger and thumb of one hand, while the flexed elbow is 
rotated with the other hand. The head of the humerus has the same direction as 
the internal condyle; its lower part can be palpated through the axilla, the arm 
being meanwhile abducted, to bring the head in contact with the under surface of 
the capsule. It is through this, the weakest part of the capsule, that the head is 
driven in the common varieties of dislocation of the shoulder, viz. those due to 
foreible abduction. The upper epiphysis of the humerus includes the head and the 
greater part of the tuberosities. The capsule is mainly attached to the epiphysis ; 
hence, in children, we find that separation of the upper epiphysis takes the place of 
dislocation. Disease in the upper end of the diaphysis does not necessarily involve 
the cavity of the joint. The bicipital groove of the humerus, which lies immedi- 
ately external to the lesser tuberosity, may he mapped out upon the surface by 
drawi ing a lne, two inches im length, downwards along the axis of the humerus 
from the tip of the acromion. When there is effusion into the joint, the arm ‘be- 
comes slightly abducted, and there is fulness in front, along the line of the long 
tendon of the biceps. With the elbow at the side the inferior part of the capsule 
of the shoulder-joint is loose and folded upon itself to form a dependent pocket ; 
if, after an injury, the arm be retained too long in this position, the patient may be 
unable to abduct the arm in consequence of the formation of adhesions in and 
around the pouch. To evacuate pus from the shoulder jomt, the integuments, 
deltoid, and capsule should be cut into by an incision passing vertically downwards 
from the tip of the acromion. 
THE AXILLA. 
The anterior fold of the axilla, formed by the lower border of the pectoralis 
major, extends from the fifth rib to the middle of the anterior border of the deltoid. 
With the arm abducted, the interval between the sternal and clavicular fibres of 
the pectoralis major is imdicated by a slight groove extending downwards and out- 
wards from the inner end of the clavicle. The sternal fibres, along with the 
pectoralis minor, are removed in a complete operation for malignant disease of the 
breast, the pectoral branches of the thoracic axis artery being secured as they 
cross the interval between the sternal and clavicular portions of the greater pectoral, 
The posterior fold of the axilla, formed by the latissimus dorsi and the teres major 
muscles, is on a lower level ‘abe the anterior fold, and leaves the chest a little in 
front of the inferior angle of the scapula. Between the two folds, and running in 
the long axis of the limb, from the axilla to the middle of the upper arm, is “the 
prominence of the coraco- -prachialis muscle. The pulsations of the third part of 
the axillary artery may be felt in the furrow immediately behind this prominence 
at the junction of the anterior and middle thirds of the outer wall of the axilla. 
Female Mamma.—The breast tissue proper is arranged to form a central 
portion, the corpus mamme, and a peripheral portion, made up of branching 
processes which radiate into the paramammary fat and become continuous 
ultimately with the connective-tissue septa of the subcutaneous fatty tissue. The 
mamma, therefore, has no distinct capsule. In the young adult nullipara, the 
corpus Mamme is compact and well defined, and contains but little intramammary 
fat, while the peripheral processes are relatively small. In multipara, the corpus 
mamme contaims more fat, and the peripheral processes extend more widely into 
the paramammary fat. 
The arrangement and extent of the parenchyma can be well seen by treating the breast with 
a 5 per cent solution of nitric acid. If shees of the fresh organ be placed in this solution for a 
few minutes and then washed under running water, the albumen of the epithelial cells of the 
parenchyma is coagulated, while the tonnective tissue is rendered translucent and somewhat 
gelatinous. The ultimate lobules of the parenchyma now appear as little (1 to 2 mm.), dull, opaque, 
white, sago-like bodies, arranged in grape-lke clusters around the finer branches of the ducts. 
The parenchyma is prolonged into the peripheral processes, into the suspensory 
ligaments of Cooper, and into the loose retromammary cellular tissue and pectoral 
