organ subunit 器官单位 A part of an organ that constitutes a distinct modular sub-unit. In some cases, the organ may also contain other sub-units of identical or similar types, in other cases this may be a distinct entity. FMA distinguishes segment from zone by whether the fiat boundaries are fixed/anchored (segments) or floating (zone). It's not completely clear how to apply this distinction FMA:86140 Organ region with one or more anchored fiat boundaries. Examples: artery, trunk of nerve, cervical part of esophagus, pelvic part of vagina, horn of thyroid cartilage, anterior segment of eyeball. Organ region with one or more fixed or anchored fiat boundaries. Examples: artery, trunk of nerve, cervical part of esophagus, pelvic part of vagina, horn of thyroid cartilage, anterior segment of eyebal. UBERON:0000063 organ region with fixed fiat boundary organ region with fixed fiat boundary organ segment organ segment segment of organ segment of organ uberon FMA通过平面边界是固定/锚定（分段）还是浮动（区域）来区分分段和区域。 如何应用这种区别还不完全清楚 具有一个或多个固定或锚定平面边界的器官区域。例如：动脉、神经干、食管颈部、阴道骨盆部位、甲状软骨角和眼球前部。 具有一个或多个锚定平面边界的器官区域。例如：动脉、神经干、食道颈部、阴道骨盆部位、甲状软骨角和眼球前段。 具有固定平面边界的器官区域 具有固定平面边界的器官区域 器官部分(organ segment) 器官部分(organ segment) 器官部分(segment of organ) 器官部分(segment of organ) 构成独特模块化子单元的器官的一部分。在某些情况下，器官也可能含有其他相同或相似类型的亚单位，在其他情况下，这可能是一个不同的实体。 organ part 器官部分