The carotid sheath is an anatomical structure that extends from the base of the skull down to the mediastinum and encompasses the internal carotid artery, the internal carotid vein, the external carotid artery, and the common carotid artery. This sheath is part of the carotid fascia, which is a continuation of the carotid fascia, and its role is to protect our important blood vessels. Inside the carotid sheath is an important nerve, the vagus nerve, which is located inside the carotid sheath, underneath the internal carotid artery and the internal carotid vein, and these important vessels and nerves are protected by the carotid sheath. The surface of the carotid sheath is the superficial muscles of our neck, like some muscles in front of the strength, such as the sternocleidomastoid muscle and the scapulolingual muscle, are on the surface of the carotid sheath. Behind the carotid sheath are the prevertebral muscles and the cervical vertebrae, and on its inner side are the trachea, the thyroid gland, and the esophagus. Therefore, the carotid sheath is a relatively important structure and a landmark to be positioned during our surgery.