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The temporomandibular joints are one of the few synovial joints in the human body with an articular disc, another being the sternoclavicular joint. The disc divides each joint into two compartments, the lower and upper compartments. These two compartments are synovial cavities, which consist of an upper and a lower synovial cavity.
Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, [1] and is a structural component of many body parts including the rib cage ...
Evolution. Meckel's cartilage is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first branchial arch in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. [1]
Later in development, the bone structure breaks loose from the jaw and migrates to the inner ear area. The structure is known as the middle ear, and is made up of the stapes, incus, malleus, and tympanic membrane. These correspond to the columella, quadrate, articular, and angular structures in the amphibian, bird or reptile jaw. [3]
The columella form thin, bony structures in the interior of the skull and serve the purpose of transmitting sounds from the eardrum. It is an evolutionary homolog of the stapes, one of the auditory ossicles in mammals. In many species, the extracolumella is a cartilaginous structure that grows in association with the columella.
The ends of epiphyses are covered with hyaline cartilage ("articular cartilage"). The longitudinal growth of long bones is a result of endochondral ossification at the epiphyseal plate. Bone growth in length is stimulated by the production of growth hormone (GH), a secretion of the anterior lobe of the pituitary gland.
The evolution of mammalian auditory ossicles was an evolutionary process that resulted in the formation of the bones of the mammalian middle ear. These bones, or ossicles, are a defining characteristic of all mammals. The event is well-documented [1] and important [2][3] as a demonstration of transitional forms and exaptation, the re-purposing ...
A glomus jugulare tumor is a tumor of the part of the temporal bone in the skull that involves the middle and inner ear structures. This tumor can affect the ear, upper neck, base of the skull, and the surrounding blood vessels and nerves. A glomus jugulare tumor grows in the temporal bone of the skull, in an area called the jugular foramen.