PECTORAL REGION 9 



patch of .coloured integument which is called the areola 

 mamma. Within the nipple, and also subjacent to the 

 areola, there is no fat. A curious change of colour occurs in 

 this region during the second month of pregnancy. At that 

 time the delicate pink colour of the skin of the nipple and 

 areola of the virgin becomes converted to brown, by the 

 deposition of pigment, and it never again resumes its 

 original appearance. 



The mamma extends, in a horizontal direction, from 

 the side of the sternum to very nearly the mid-axillary line 

 on the side of the thorax, and, in a vertical direction, from 

 the second costal arch above to the sixth costal cartilage 

 below. About two-thirds of the gland are placed upon the 

 pectoralis major muscle, whilst the remaining part, which 

 corresponds to its inferior and lateral third, extends beyond 

 the anterior fold of the axilla, and lies upon the serratus 

 anterior muscle. From the part which lies in relation to the 

 lower border of the pectoralis major a prolongation extends 

 upwards into the axilla, and reaches as high as the third rib. 



The mamma is not isolated by a capsule from the 

 surrounding fatty tissue of the superficial fascia. Pervading 

 it, and supporting the true glandular substance, there are 

 strands or trabeculae of connective tissue which constitute its 

 stroma or framework, and these are directly continuous with 

 the fibrous tissue which supports the fat of the superficial 

 fascia. The stroma and gland-substance together constitute 

 a conical mass termed the corpus mamma. Processes pro- 

 ject out from both the surface and margins of the corpus 

 mammae, and in the hollows between these projections 

 is deposited the fat which gives the smooth contour to the 

 organ. Many of the processes which extend from the super- 

 ficial surface are attached to the deep surface of the skin. 

 They form the so-called ligaments of Cooper. 



The gland substance is arranged in lobes and lobules, and 

 the ducts issuing from these converge towards the areola. 

 Some fifteen or more lactiferous ducts pass towards the base 

 of the nipple. Subjacent to the areola the ducts expand 

 into fusiform dilatations termed the sinus lactiferi, and then, 

 contracting, they traverse the substance of the nipple, upon 

 the summit of which they open. 



In a well - injected subject twigs from the intercostal 

 arteries, and also from the perforating branches of the 



