THE THORAX. 113 



teen to twenty in number; these converge towards the 

 areola, and beneath the nipple become dilated into si- 

 nuses, before perforating its summit by separate orifices. 

 The mammary gland is separated from the pectoralis 

 major and minor, the serratus magnus, and its sheath by 

 a layer of cellular tissue which allows of the free move- 

 ment of the gland over it, an important point in the 

 diagnosis of breast tumors. 



The breast is freely supplied with vessels, the arteries 

 being derived from the internal mammary, the long 

 thoracic from the axillary, and the intercostals ; the 

 veins are both superficial and deep : the superficial are 

 seen beneath the subcutaneous cellular tissue, and are 

 very much distended during pregnancy, whilst the deeper 

 ones follow the course generally of the arteries. An 

 anastomotic circle of veins is seen around the base of 

 the nipple. The lymphatics are also arranged as super- 

 ficial and deep: the former are immediately beneath the 

 integument and pass into the axillary glands ; the latter 

 set accompany the galactiferous tubes, and pass into the 

 cellular tissue beneath the gland, also to join the glands 

 in the axilla and the intrathoracic ganglia. The nerves 

 are derived from the brachial and cervical plexuses and 

 from the intercostals. 



The breast is the seat of many forms of tumors which 

 necessitate its removal, and its great vascularity gives 

 rise to severe hemorrhage during such operations; it is 

 advisable, therefore, in such cases to make the inferior 

 incision first, to avoid, if possible, any complication, 

 owing to the parts being obscured by blood. Mammary 

 abscesses ought to be opened vertically (to avoid " pocket- 

 ing " and the formation of sinuses), freely and deeply, 

 to insure the exit of all matter. Moreover, these in- 



