THE MAMMA OR BREAST 185 



breast anastomose with those of the surrounding structures; hence in certain cases the 

 pectoralis muscles and even the pleura may be affected, and when the disease is widely 

 disseminated by the lymph-channels on the chest-walls there is produced the thick- 

 ened, brawny, infiltrated condition known as the cancer " en cuirasse" of Velpeau. 

 Nerves. The breast and the skin over it are supplied from the descending 

 branches of the cervical plexus, by thoracic branches from the brachial plexus, and 

 by the second, third, fourth,, fifth, and sixth intercostals. These are not of so much 

 practical importance as the lateral branches of the second and third intercostal 

 nerves. That of the second is called the intercostobrachialis {humeral) nerve ; it 

 crosses the axilla, anastomoses with the medial brachial {lesser internal) cutaneous 

 nerve, and supplies the skin of the inner and upper portion of the arm. The third 

 intercostal anastomoses with the second and gives a branch to the arm and to the 

 dorsum of the scapula. These nerves are certain to be seen in clearing out the axilla. 

 Their division is accompanied by no paralysis, but disturbance of them accounts for 

 some of the pain and discomfort following the operation. 



ABSCESS OF THE BREAST. 



Suppuration in the mammary gland is usually due to infection which has 

 entered the gland either through the lymphatics or the lactiferous ducts. The 

 starting point of the infection is thought to be an ulcerated crack or fissure of the 

 nipple. Infection travelling into the gland by way of the lymphatics would cause 

 pus primarily in the pericanalicular tissue but it would soon involve the lactiferous 

 ducts and then pus might exude from the nipple. Infection travelling up the ducts 

 might reach the ultimate lobules and therefore give rise to widespread and multiple 

 abscesses. Suppuration in this gland resembles that in the parotid gland, already 

 described. When the body of the gland is involved it is apt to be so in more than 

 one spot. The infection follows the branching of the ducts and usually there are 

 several small abscesses instead of one large one. If there is a large collection of pus 

 it is fk>t contained in one cavity but more likely in several. This is so often the case 

 that in treating these abscesses it is advised that they should not only be incised but 

 the finger should then be introduced and the partitions separating the various abscess 

 cavities broken through. 



Tn its incipiency a lymphatic infection may cause a single collection of pus, but 

 this soon breaks through into the canaliculi and infects and involves the glandular 

 structure. In an early stage of duct infection several inflammatory areas may start 

 up about the same time. The pus soon breaks through the canaliculi and involves 

 the periglandular tissue so that in each mode of infection the condition soon becomes 

 the same. It is for this reason that it is difficult to say whether the infection origi- 

 nated in the lymphatics or the ducts. 



When the ducts are inflamed the pus often finds a vent at the nipple. The fre- 

 quency of this is the reason why direct infection of the ducts is regarded as the more 

 common mode. In incising a mammary abscess the incisions should follow the course 

 of the ducts, that is, they should be made in a direction radiating from the nipple towards 

 the circumference and not transversely, otherwise healthy ducts will be divided. 



Submammary Abscess (for subpectoral abscess see page 264). As has been 

 pointed out some of the glandular tissue dips down to the pectoral fascia, hence 

 when some of these deepest lying lobules are inflamed the pus instead of breaking 

 laterally into the adjoining lobules or tissue breaks into the submammary tissue and 

 bursa. Here it spreads rapidly beneath the gland and raises the gland above it. 

 As the pus accumulates it sinks downward and works its way outward to the lower 

 outer quadrant along the edge of the anterior axillary fold. Here is where it should 

 be opened. As the cavity is single one incision is sufficient to drain it. 



TUMORS OF THE MAMMARY GLAND. 



Benign Tumors. There are two main kinds of benign mammary growths, 

 cystic and adenomatous or fibro-adenomatous. 



Cystic growths due to retention of secretion of the ducts occur as small, rounded 

 tumors, painful and tender to the touch, and are seen between the ages of 25 and 35 



