The sudden appearance of a pit below the zygomatic bone of the left cheek may be caused by muscle atrophy, malnutrition and other factors. 1. Muscle atrophy: when the patient’s local nerve dysfunction occurs, it can lead to muscle atrophy under the zygomatic bone of the left cheek, resulting in the appearance of a pit. Patients need to consult a doctor in a timely manner, after clarifying the condition, under the guidance of the doctor can be applied to methylcobalamin and other nutritive nerve drugs, but also need to eat a high protein diet to promote the growth of nerve cells and skeletal muscle cells. 2. Malnutrition: Long-term poor dietary habits, vegetables, fruits and other food intake is low, can trigger body malnutrition, resulting in a lack of micronutrients, can cause the left cheek zygomatic bone below the depression. It is recommended that patients with depression below the cheek zygomatic bone and other discomforts should consult a doctor in time to evaluate their condition and follow the doctor’s instructions for treatment.