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Scattered Haversian canals are also found in ectotherms like cryptodire turtles. [6] Among extinct groups, dense Haversian vascularization is only present in stem-birds (dinosaurs) and stem-mammals (therapsids) [ 7 ] while scattered Haversian systems can be found in ichthyosaurs , phytosaurs , basal stem-mammals (e.g. Ophiacodon ), Limnoscelis ...
The single canal found in hagfish appears to be secondarily derived. Additionally, the vestibular systems of lampreys and hagfish differ from those found in other vertebrates in that the otolithic organs of lampreys and hagfish are not segmented like the utricle and saccule found in humans, but rather form one continuous structure referred to ...
Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the Haversian canal. The Haversian canal contains the bone's blood supplies. The boundary of an osteon is the cement line. Each Haversian canal is surrounded by varying number (5-20) of concentrically arranged lamellae of bone matrix.
The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles (malleus, incus, and stapes), which transfer the vibrations of the eardrum into waves in the fluid and membranes of the inner ear .
Within the bone itself, the haversian canals become blocked with scar tissue, and the bone becomes surrounded by thickened periosteum. [ citation needed ] Due to the avascular nature of this bone, antibiotics which travel to sites of infection via the bloodstream poorly penetrate these tissues, hence the difficulty in treating chronic ...
The semicircular canals are three semicircular interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the lateral, anterior and posterior semicircular canals. They are the part of the bony labyrinth, a periosteum-lined cavity on the petrous part of the temporal bone filled with perilymph.
The inner ear comprises three specialized regions of the membranous labyrinth: the vestibular sacs – the utricle and saccule, and the semicircular canals, which are the vestibular organs, as well as the cochlear duct, which is involved in the special sense of hearing.
The spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2 3 ⁄ 4 turns about the modiolus. The cochlear structures include: Three scalae or chambers: the vestibular duct or scala vestibuli (containing perilymph), which lies superior to the cochlear duct and abuts the oval ...