[Location] Localized in the supine position, on the chest, directly below the nipple, at the base of the breast, in the fifth intercostal space, 4 cun lateral to the anterior median line. (Fig.44)
 
[Regional Anatomy] Skin→subcutaneous tissue→pectoralis major. Superficial layer, the lateral crural cutaneous branch of the fifth thoracic nerves, and the subordiantial ramus of thoracoepigastric vein; deep layer, the branches or the subordiantial ramus of the lateral thoracic artery and vein, the branches of the medial and lateral thoracic nerves, the fifth intercostal nerves, and the fifth posterior intercostals arteries and veins.