This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Surfaces and Grooves, Subject name: Anatomy
Muscle of expiration 
Select and explain. 
A. External intercostal, B. Diaphragm, C. Internal intercostal, D. Serratus anterior
C: Internal intercostal
Answer: C: Internal intercostal 
Explanation: MUSCLE OF INSPIRATION: Quiet: Diaphragm External intercostals Interchondral pa of internal intercostal of contralateral side. Deep: Erector spinae Scalene muscles Pectoral muscles Serratus anterior MUSCLE OF EXPIRATION: Quiet: Passive process d/o inherent quality of lungs Forced: Muscles of anterior abdominal wall with internal intercostal (except interchondral pa)