This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
A patient presents with a penetrating chest wound associated with intrathoracic haemorrhage. A thoracotomy is done by taking an incision in the 41h/51h intercostals space staing 1 cm away from the lateral margin of the sternum.This is done to avoid injury to the 
Select and explain. 
A. Pleura, B. Intercostal aery, C. Internal thoracic aery, D. Intercostal nerve
C: Internal thoracic aery
Answer: C: Internal thoracic aery 
Explanation: C i.e. Internal thoracic aeryIntercostal (external, internal & innermost) muscles (not transverses thoracic) are pierced in pleural taping in mild axillary line.Latissimus dorsi, serratus anterior, rhomboidus major & intercostal muscles are cut in posterolateral thoracotomy whereas pectoralis is cut in anterior & anterolateral approach.Thoracotomy in upper 6 intercostal spaces is done by taking an incision 1 cm lateral to sternum to avoid injury to internal thoracic (mammary) aeryQ.