・後頭蓋窩の正中の最前部に位置する形になる。
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鼻腔断面 |
鼻腔断面（色分け） |
頭蓋窩 |
頭蓋窩（色分け） |
以下は「Wikipedia」の解説文となる。
The clivus (/ˈklaɪvəs/,[1] Latin for "slope"), or Blumenbach clivus, is a bony part of the cranium at the base of the skull. It is a shallow depression behind the dorsum sellae of the sphenoid bone. It slopes gradually to the anterior part of the basilar occipital bone at its junction with the sphenoid bone. It extends to the foramen magnum. It is related to the pons and the abducens nerve (CN VI).
【 語 句 】
・cranium：頭蓋 ・dorsum sellae：鞍背 ・sphenoid bone：蝶形骨 ・basilar occipital bone：後頭骨底部 ・foramen mugnum：大後頭孔 ・pons：橋 ・abducens nerve：外転神経
【Structure】
The clivus is a shallow depression behind the dorsum sellae of the sphenoid bone. It slopes gradually to the anterior part of the basilar occipital bone at its junction with the sphenoid bone. It extends to the foramen magnum. On axial planes, it sits just posterior to the sphenoid sinuses. It is medial to the foramen lacerum (the internal carotid artery reaches the middle cranial fossa above the foramen lacerum), proximal to its anastomosis with the Circle of Willis. It is anterior to the basilar artery.
The pons sits on the clivus. The abducens nerve (CN VI) also tracks along the clivus during its course.
【Variations】
During embryonic development, the clivus is formed by the fusion of the basiocciput and basisphenoid or also known as the sphenooccipital synchondrosis. When the fusion occurs improperly, it would give rise to gaps that are considered anatomical variations. Variations of the clivus include fossa navicularis magna, craniopharyngeal canal, canalis basilaris medianus, and transverse basilar fissure (Saucer's fissure). Ossification of the apical ligament of dens may also occur, resulting in a variant bony tubercle at the inferior end of the clivus. Condylus tertius and arcus praebasiocipitalis are the other two variations that can be found at the lower end of the clivus, although their etiology may be different from the other variations.
【 語 句 】
・axial plane：軸平面 ・sphenoid sinuses：蝶形骨洞 ・foramen lacerum：破裂孔 ・internal carotid artery：内頚動脈 ・middle cranial fossa：中頭蓋窩 ・anastomosis with～：～との吻合 ・Circle of Willis：ウィリス動脈輪 ・basilar artery：脳底動脈 ・embryonic：胎生の ・fusion：融合 ・basiocciput：基後頭骨 ・basisphenoid：基蝶形骨 ・sphenooccipital synchondrosis：蝶後頭軟骨結合 ・fossa navicularis magna：大後頭舟状窩？ ・craniopharyngeal canal：頭咽頭管 ・canalis basilaris medianus：？ ・transverse basilar fissure：横脳底裂？ ・ossification：骨化 ・apical ligament of dens：歯尖靭帯 ・condylus：顆状突起; 顆; 顆突起 ・tertius： ・arcus：弓 ・etiology： 原因論、病因(学)
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