This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
In evaluating a breast lesion in a female athlete, the surgeon notes that the tumor is in the anterior axillary line. To which site does the lateral edge of normal breast tissue extend? 
Select and explain. 
A. The lateral edge of the pectoralis major muscle, B. The medial edge of the pectoralis minor muscle, C. Cover the medial third of the serratus anterior muscle, D. The semispinalis capitis
C: Cover the medial third of the serratus anterior muscle
Answer: C: Cover the medial third of the serratus anterior muscle 
Explanation: The breast tissue extends over the medial margin of the serratus anterior muscle. The nerve to the serratus anterior lies on the lateral aspect of this muscle and may be accidentally injured during breast surgery.