Which of the following activities is NOT primarily controlled by the medulla oblongata?

The medulla oblongata is a vital part of the brainstem that plays a crucial role in autonomic functions. It primarily regulates involuntary activities such as heart rate, breathing, and blood pressure. The heart rate regulation involves the medulla's role in autonomic nervous system responses. Breathing control is another key function of the medulla; it houses the respiratory centers that manage the rhythm and depth of breathing. Blood pressure regulation also involves the medulla, as it contributes to the autonomic control of vasodilation and vasoconstriction in response to blood pressure changes.

In contrast, voluntary movement coordination is not primarily a function of the medulla oblongata. This activity is mainly regulated by the cerebellum and the motor cortex, which are responsible for fine motor control, coordination, and the execution of voluntary movements. This distinction clarifies why the coordination of voluntary movement does not fall under the primary responsibilities of the medulla.