Middle ear to sounds of higher frequency, because these are better taken up by the inner ear (which also responds to higher frequencies than those of non-mammals). The malleus, or "hammer", evolved from the articular bone of the lower jaw, and the incus, or "anvil", from the quadrate. In other vertebrates, these bones form the primary jaw joint, but the expansion of the dentary bone in mammals led to the evolution of an entirely new jaw joint, freeing up the old joint to become part of the ear. For a period of time, both jaw joints existed together, one medially and one
Ear piercing instrument it with a piercing gun, which later required reconstructive surgery. This is one area where both the body piercing community and supporters of piercing guns do agree, and most responsible manufacturers of piercing guns strongly advise against such use. However, some less reputable users of piercing guns still continue to offer such piercings. Ear piercing instrument An ear piercing instrument (commonly referred to as a piercing gun or an ear piercing gun) is a device designed to pierce earlobes by driving a pointed starter earring through the lobe. Piercing guns may be reusable or disposable. Piercing guns are typically used