・3部構成となるため「三半規管」とも呼ばれる。
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骨迷路・膜迷路 |
骨迷路 |
膜迷路 |
骨迷路 |
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| 迷路と神経 |
外リンパ腔・膜迷路 |
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以下は「Wikipedia」の解説文となる。
The semicircular canals or semicircular ducts are three semicircular, interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the horizontal, superior and posterior semicircular canals.
【Structure】
The semicircular canals are a component of the bony labyrinth that are at right angles from each other. At one end of each of the semicircular canals is a dilated sac called an osseous ampulla which is more than twice the diameter of the canal. Each ampulla contains an ampullary crest, the crista ampullaris which consists of a thick gelatinous cap called a cupula and many hair cells. The superior and posterior semicircular canals are oriented vertically at right angles to each other. The lateral semicircular canal is about a 30-degree angle from the horizontal plane. The orientations of the canals cause a different canal to be stimulated by movement of the head in different planes, and more than one canal is stimulated at once if the movement is off those planes. The lateral canal detects angular acceleration of the head when the head is turned and the superior and posterior canals detect vertical head movements when the head is moved up or down. When the head changes position, the endolymph in the canals lags behind due to inertia and this acts on the cupula which bends the cilia of the hair cells. The stimulation of the hair cells sends the message to the brain that acceleration is taking place. The ampullae open into the vestibule by five orifices, one of the apertures being common to two of the canals.
Among species of mammals, the size of the semicircular canals is correlated with their type of locomotion. Specifically, species that are agile and have fast, jerky locomotion have larger canals relative to their body size than those that move more cautiously.
【 語 句 】
・inner ear：内耳 ・bony labyrinth：骨迷路 ・right angle：直角 ・dilated：膨らんだ ・sac：嚢 osseous ampulla：骨膨大部 ・ampullary crest：膨大部稜 ・crista ampullaris：膨大部稜 ・gelatinous：ゼラチン状の ・capula：膨大部頂？ ・hair cell：有毛細胞 ・orient：方向づける ・orientation：方向 ・plane：（水平）面 ・angular acceleration：角加速度 ・endolymph：内リンパ ・lag behind：遅れる ・inertia：慣性 ・ciia：絨毛 ・vestibule：前庭 ・orifice：開口部 ・aperture：穴 ・locomotion：移動（力） ・agile：機敏な ・jerky：ぎくしゃく動く
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