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In other words, jaw joints and ears do not define any except the most recent groups of mammals. Mammalian and non-mammalian jaws. In the mammal configuration, the quadrate and articular bones are much smaller and form part of the middle ear. Note that in mammals the lower jaw consists of only the dentary bone. [24]
This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group of ...
The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates , the inner ear is mainly responsible for sound detection and balance. [ 1 ] In mammals , it consists of the bony labyrinth , a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts: [ 2 ]
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 lower jaw defines the chin. The simpler structure is found in jawless fish, in which the cranium is normally represented by a trough-like basket of cartilaginous elements only partially enclosing the brain, and associated with the capsules for the inner ears and the single nostril. Distinctively, these fish have no jaws.
The central portion of the tympanic part is thin, as it gives rise to the bony inner two-thirds of the ear canal, and in 5 - 20% of skulls the lower surface is perforated by a hole, the foramen of Huschke [1] that opens onto the temporomandibular joint due to incomplete fusion of the anterior and posterior prominences during development.
Facing the inner ear, the medial wall (or labyrinthic wall, labyrinthine wall) is vertical, and has the oval window and round window, the promontory, and the prominence of the facial canal. Facing the outer ear , the lateral wall (or membranous wall ), is formed mainly by the tympanic membrane , partly by the ring of bone into which this ...
The inner ear consists of the cochlea and several non-auditory structures. The cochlea has three fluid-filled sections (i.e. the scala media, scala tympani and scala vestibuli) , and supports a fluid wave driven by pressure across the basilar membrane separating two of the sections.