Final answer:
Popping and crackling in skin may indicate subcutaneous emphysema, while similar sounds in joints are usually due to joint lubrication. Marsha's respiratory symptoms and chest radiograph indicate that the likely cause of her symptoms is a respiratory issue.
Step-by-step explanation:
Popping and crackling sounds in the subcutaneous layer of the skin can indicate the presence of air, which is often referred to as subcutaneous emphysema, usually as a result of a pathologic process, rather than normal physiologic function. Meanwhile, the popping and crackling sounds in the joints typically result from the release of gas bubbles within the synovial fluid of the joint space, which is a normal occurrence and part of joint lubrication.
However, considering the clinical focus on Marsha's symptoms, such as crepitation in the lungs observed via stethoscope and abnormalities detected through a chest radiograph, the most concerning cause pointed out pertains to respiratory issues. These findings suggest Marsha could be experiencing a pulmonary condition that requires further medical evaluation.