the structures that surround and contact the parotid gland, forming the boundaries of the parotid space: anteriorly, the ramus of the mandible flanked by the masseter and medial pterygoid muscles; medially, the pharyngeal wall, carotid sheath and structures originating from the styloid process; posteriorly, the mastoid process, sternocleidomastoid muscle, and posterior belly of the digastric muscle; superiorly, the temporomandibular joint and the tympanic bone and cartilaginous portion of the external acoustic meatus.