What muscle groups are primarily involved in the oral preparatory phase?

The oral preparatory phase of swallowing is crucial for properly manipulating and preparing food for swallowing, and it involves several key muscle groups. The primary muscle groups active during this phase are the muscles of mastication, which include the masseter, temporalis, and pterygoid muscles. These muscles are responsible for chewing and grinding food into manageable pieces. Additionally, the facial muscles, including the orbicularis oris and buccinator, play a vital role in manipulating food within the mouth, ensuring that it is well-mixed with saliva and forming a cohesive bolus that can be swallowed effectively.

In contrast, the other muscle groups mentioned in the options serve different functions related to swallowing but are not during the oral preparatory phase. The diaphragm and intercostals are primarily involved in respiration rather than the initial preparatory phases of swallowing. Pharyngeal constrictors and laryngeal muscles are more active during the pharyngeal phase of swallowing, helping to transport the bolus from the oropharynx to the esophagus. Lastly, the smooth muscles of the esophagus are involved in the esophageal phase of swallowing, which occurs after the bolus has been swallowed. Thus, the involvement of both mastication and facial