There are many theories surrounding the relationship between TMD and aural symptoms. Many of these theories are based off of the discovery by Costen in 1934, who initially associated TMD with aural dysfunction. A dislocated disc in the jaw joint increases pressure in the Eustachian tube, as well as the auriculotemporal nerve. The auriculotemporal nerve innervates the TMJ, giving stimulation, which then gives the sense of Otalgia. Additionally, a dislocated disc can lead to inflammation in the tensor palatini muscles, which can also cause Eustachian tube obstruction. This creates ear pain and fullness/stuffiness. Another theory proposes that common innervation of the tensor veli palatini, tensor tympani, masseter, temporalis and pterygoid muscles is the underlying cause of the aural symptomatology in TMD patients. Studies have shown that the tensor tympani muscle is dysfunctional in TMD patients, making them subject to hearing loss. Severity is correlated with the degree of intraoral opening in addition to other symptoms. TMD patients have an impaired ROM, leading to poor Eustachian tube function, and impeding the performance of the tensor tympani. Tinnitus, Vertigo and Otalgia can all be a result of this malfunction.