International Board of Certified Lactation Consultant (IBCLC) Practice Exam

What type of muscle fibers is the nipple primarily made of?

1. Skeletal

2. Smooth

3. Cardiac

4. Striated

The correct answer is: Smooth

The correct answer is smooth muscle fibers. The nipple is primarily composed of smooth muscle tissue, which is critical for its function. This type of muscle is involuntary, meaning it operates automatically without conscious control. It helps facilitate the process of breastfeeding by responding to various stimuli. For example, during breastfeeding, smooth muscle contractions help to compress the ducts within the nipple, aiding in the ejection of milk. Smooth muscle fibers in the nipple are particularly important because they allow for the required flexibility and responsiveness to various physiological signals, such as oxytocin release during breastfeeding. This is crucial in ensuring effective milk delivery to the infant. In contrast, skeletal muscle fibers, which are voluntary and under conscious control, are not present in the nipple. Skeletal muscle is typically associated with the movement of limbs and body parts rather than the involuntary functions required in lactation. Cardiac muscle, found only in the heart, is also not relevant in this context as it serves a different physiological function unrelated to lactation. Striated muscle generally refers to skeletal and cardiac muscles due to their appearance under the microscope, but in the case of the nipple, the smooth muscle fibers play the significant role necessary for its operation during breastfeeding.