Image Credit: NASA. Asked by Jon Gray. An impact basin known as Valhalla is Callistoâs largest crater with a diameter of over 300 kilometres (190 miles), while concentric rings that surround it extend out to 3,000 kilometres (1,900 miles) â nearly large enough for the entire USA to fit within its boundaries.
Somewhat surprisingly, the second most common cause of tinnitus is head and neck injuries. In a clinical study of 2,400 tinnitus patients at the Oregon Health Science University, more than 12% reported that their tinnitus had been caused by head or neck injury. (1) There are two broad categories of head and neck injury, Traumatic Brain Injury (TBI) and whiplash.
The exact mechanism for the production of objective tinnitus in patients with middle-ear myoclonus is a controversial issue. According to some authors, this type of tinnitus is caused by muscular contraction (muscular sound) of the stapedius or tensor tympani muscles [9].ACKGROUND. Tinnitus caused by middle-ear myoclonus is an extremely rare but often very distressing condition, with only few case reports published in the literature [1 ,3- 6]. It is produced by abnormal, repetitive, rhythmical contractions of the middle-ear muscles: the tensor tympani and the stapedius [1].