Bones of the Auditory Canal (Enlarged 20 times their natural size)

We call the ossicles or chain of tiny bones the three smallest bones in the human body, joined together by joints. They are found in the middle ear. Malleus (Hammer), Incus (Anvil) and Stapes (Stirrup). Their function is to transmit incoming sound from the eardrum through the oval window to the inner ear, thus causing a mechanical intensification of the sound. In case we are subjected to very loud noises, it is important to protect the inner ear from permanent damage. This is possible thanks to a reflex that triggers certain muscle activity (M. stapedius). As a result of this, the stirrup adopts a slightly tilted position, so that the intensity of the sound can only be transmitted in parts. When there are too strong movements of the ossicular chain (for example when we cough or sneeze) there is another muscle that has a protective function (M. tensor tympani), its tendon is inserted in the hammer and it tightens the eardrum. A typical disease that affects the ossicles of the ear and involves their stiffness and consequent hearing loss is otosclerosis. Our model is an enlarged replica of original bone pieces using Micro-CT