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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 (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 ...
Within mammals and other synapsids the columella has evolved into the stapes, a homologous bone within the newly evolved inner ear. As the tympanic cavity evolved to reduce in size, the columella shortened in length. The stirrup-shaped articular processes of the columella inspired a new name for this auditory ossicle, the stapes. The auditory ...
In a TMME, the ear ossicles are reduced and nearly detached from the back of the jaw, but still retain a connection via a slender ossified meckelian cartilage. [2] Chaoyangodens adds valuable information to the study of mammalian ear evolution, since it has the oldest complete stapes ("stirrup" ossicle) reported in true mammal fossils. The ...
The ossicles are the malleus (hammer), incus (anvil), and the stapes (stirrup). The stapes is the smallest named bone in the body. The middle ear also connects to the upper throat at the nasopharynx via the pharyngeal opening of the Eustachian tube. [3] [11] The three ossicles transmit sound from the outer ear to the inner ear.
The stapes is one of three ossicles in mammals. In non-mammalian tetrapods , the bone homologous to the stapes is usually called the columella ; however, in reptiles , either term may be used. In fish, the homologous bone is called the hyomandibular , and is part of the gill arch supporting either the spiracle or the jaw, depending on the species.
These bones form the middle ear in later mammal groups (see Evolution of mammalian auditory ossicles); they include the incus , malleus , ectotympanic and prearticular. [ 1 ] In Mesozoic mammals these bones gradually change position and size until they are incorporated in the middle ear.
In mammals, the articular bone evolves to form the malleus, one of the mammalian ossicles of the middle ear. This is an apomorphy of the mammalian clade, [4] and is used to determine the fossil transition to mammals. [5] It is analogous to, but not homologous to the articular process of the lower jaw.