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 pain secondary (referred) pain is more common in adults. Primary ear pain is most commonly caused by infection or injury to one of the parts of the ear. Many conditions involving the external ear will be visible to the naked eye. Because the external ear is the most exposed portion of the ear, it is vulnerable to trauma or environmental exposures. Blunt trauma, such as a blow to the ear, can result in a hematoma, or collection of blood between the cartilage and perichondrium of the ear. This type of injury is particularly common in contact sports such as wrestling and