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
Anvil this manufacturing method is no longer in use. At one end, the common smith's anvil has a projecting conical "bick" ("beak", "horn") used for hammering curved work pieces. The other end is typically called the heel. Occasionally, the other end is also provided with a bick, partly rectangular in section. Most anvils made since the late 18th century also have a hardy hole and a pritchel hole where various tools, such as the anvil-cutter or hot chisel, can be inserted and held by the anvil. Some anvils have several hardy and pritchel holes, to accommodate a wider variety of hardy