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The ossicles (also called auditory ossicles) are three irregular bones in the middle ear of humans and other mammals, and are among the smallest bones in the human body. . Although the term "ossicle" literally means "tiny bone" (from Latin ossiculum) and may refer to any small bone throughout the body, it typically refers specifically to the malleus, incus and stapes ("hammer, anvil, and ...
The ossicles may bear external projections in the form of spines, granules or warts and they are supported by a tough epidermis. Skeletal elements are sometimes deployed in specialized ways, such as the chewing organ called " Aristotle's lantern " in sea urchins, the supportive stalks of crinoids, and the structural "lime ring" of sea cucumbers.
Ossicles are small calcareous elements embedded in the dermis of the body wall of echinoderms. They form part of the endoskeleton and provide rigidity and protection. They are found in different forms and arrangements in sea urchins , starfish , brittle stars , sea cucumbers , and crinoids .
The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively. The ossicles directly couple sound energy from the eardrum to the oval window of the cochlea.
These are called the primary tentacles and were present in the common ancestor of echinoderms, but have been lost in all the other classes of the phylum, [11] and may be simple, branched or arborescent. They are known as the introvert and posterior to them there is an internal ring of large calcareous ossicles.
The evolution of mammalian auditory ossicles was an evolutionary process that resulted in the formation of the mammalian middle ear, where the three middle ear bones or ossicles, namely the incus, malleus and stapes (a.k.a. "the anvil, hammer, and stirrup"), are a defining characteristic of mammals.
The ossicles may bear external projections in the form of spines, granules or warts that are supported by a tough epidermis. Echinoderm skeletal elements are sometimes deployed in specialized ways such as the chewing organ in sea urchins called "Aristotle's lantern", the supportive stalks of crinoids, and the structural "lime ring" of sea ...
The stapes is the third bone of the three ossicles in the middle ear and the smallest in the human body. It measures roughly 2 to 3 mm , greater along the head-base span. [ 1 ] It rests on the oval window , to which it is connected by an annular ligament and articulates with the incus , or anvil through the incudostapedial joint . [ 2 ]