chap, x.] THE BREAST. 177 



child-bearing period of life. After the cessation of 

 menstruation the glandular tissue atrophies, although 

 the ducts always persist. The breast is thinner at the 

 periphery than at the centre, and is thinnest about a 

 line extending from the nipple to the sterno-clavicular 

 joint. Abscesses situated beneath the breast not un- 

 frequently make their way through the gland at some 

 point along this line. The base of the gland is flat, and 

 is separated from the pectoral muscle by much loose 

 connective tissue. It is in this tissue that the sub- 

 mammary abscess forms. There is sometimes a kind 

 of bursa between the breast and the muscle which has 

 been found to form a definite hygroma or bursal cyst 

 (Velpeau). Although the gland is but loosely con- 

 nected with the pectoralis major, yet it moves a little 

 with that muscle, and the position of the breast can 

 be slightly affected by the movement of the arm. 

 It is important, therefore, that the arm should be 

 kept at rest in inflammatory affections of the organ. 

 In cancer the gland and the muscle may become 

 intimately adherent. The nipple is situated over the 

 fourth interspace, about three-quarters of an inch 

 from the junction of the ribs with their cartilages, 

 and some four inches from the middle line. It 

 contains muscular fibres, by means of which it can be 

 rendered prominent on stimulation. The skin about 

 the nipple is very thin and sensitive, and is often the 

 seat of painful fissures and excoriations. When any 

 contracting growth, such as scirrhus, drags upon the 

 ducts of the gland, the nipple becomes retracted. 



Abscesses of the breast should be opened by in- 

 cisions radiating from the nipple, so as to avoid un- 

 necessary damage to the mammary ducts. 



The breast is supplied by the anterior cutaneous 

 branches of the second, third, fourth, and fifth inter- 

 costal nerves, and by the lateral branches of the last 

 three of those nerves. The connections of these 

 M 4 



