• Pectoral region
  
  
• Subcutaneous
  
  
• From lateral border of the sternum to mid-axillary line.
  
  
• Axillary tail extends further into axilla.
  
  
• From 2 nd to 6 th ribs.
  
  
• Nipple in 4 th intercostals space about midclavicular line.

Overlies fascia covering 4 muscles

• Pectoralis major.
  
  
• Serratus anterior.
  
  
• External oblique abdominis aponeurosis.
  
  
• Rectus abdominis

Separated from this fascia by submammary space (retro mammary space) with loose connective tissue. This is the basis for free mobility of the breast over chest wall.