STRUCTURE AND FUNCTION RELATIONS IN MIDDLE EAR

我们工作的目标是定义与外部和外部环境相关的规则， 中耳结构的功能，以便我们能够了解其功能 中耳解剖正常和病理变异的意义。 在本申请中，我们提出了旨在研究如何 鼓膜、听小骨和 中耳空气空间影响中耳性能。 的过程 所涉及的代表中耳的最外围作用。 两 分类学上的优势，将被研究。(1)四种啮齿动物 （龙猫，沙鼠，仓鼠和大鼠）已被选中，因为 在中耳和听力图上都有明显的差异。 的 结构差异在于鼓膜的大小， 听小骨，锤骨悬吊的形状和刚度，相对 中耳气腔的体积，以及中耳腔的相对大小。 副鼓膜 生理和解剖测量 将定量地确定这些结构的影响， 差异(2)猫科动物的中耳 具有很大的结构均匀性，尺寸变化很大。 的 已知家猫中耳气隙的作用是 强烈的频率依赖性，并与双腔 这是猫的特征。 利用头骨 从博物馆的藏品中，我们将对 （基本上）所有36种本科，以确定定量 将耳朵的尺寸与头骨的大小联系起来的规则。 的子集的 这些（约12种）更详细的中耳重建 将由头骨的CT扫描制成，这将产生三个 可以导出声学模型的维度描述。 将进行死后声学反应的生理测量 6-10个物种的标本（可从动物园和野生动物园获得） 部门），也将从CT扫描中重建解剖结构 和组织切片。 定量模型 将开发结构特征和生理性能， 这两个分类群和这些模型将通过测量进行检验。 我们的目标是提供一个统一的理论，其中既有不同的 这些啮齿动物的结构配置和数量 可变结构的猫科动物包括在规则，定量 描述这两种变化的功能后果。 这 系统的方法将为定量描述 中耳的病理和种间差异的影响 结构对听觉功能的影响 这样的描述将取代 轶事描述与全面的理论，可以影响 对中耳病变和中耳重建的临床认识 关于耳朵进化的观点。

The goal of our work is to define rules that relate external and middle-ear structure to function so that we can understand the functional significance of normal and pathologic variations in middle-ear anatomy. In this application we propose experiments designed to investigate how differences in the configuration of the tympanic membrane, ossicles and middle-ear air spaces affect middle-ear performance. The processes involved represent the most peripheral action of the middle ear. Two complimentary taxonomic groups, will be studied. (1) Four rodent species (chinchilla, gerbil, hamster, and rat) have been selected because of distinct differences in both their middle ears and their audiograms. The structural differences are in the size of the tympanic membrane and ossicles, the shape and rigidity of the malleus suspension, the relative volume of the middle-ear air-spaces, and the relative size of the accessory tympanic membrane. Physiological and anatomical measurements will quantitatively determine the effects of these structural differences. (2) The middle-ears of species in the cat family (Felidae) have great structural uniformity with large variations in size. The effects of the middle-ear air spaces in domestic cat are known to be sharply frequency dependent and are related to the two-cavity configuration of the spaces that is characteristic of cats. Using skulls from museum collections we will make structural measurements on (essentially) all 36 species of this family to determine quantitative rules that relate dimensions of the ear to skull size. For a subset of these (about 12 species) more detailed reconstructions of the middle ear will be made from CT scans of the skull, which will yield three dimensional descriptions from which acoustic models can be derived. Post-mortem physiological measurements of acoustic responses will be made on specimens of 6-10 species (as available from zoos and wildlife departments), which will also be reconstructed anatomically from CT scans and from histological sections. Quantitative models relating the structural features and physiologic performance will be developed for both taxonomic groups and these models will tested by the measurements. Our aim is to provide a unified theory in which both the diverse structural configurations of these rodents and the quantitatively variable structure in Felidae are included in rules that quantitatively describe the functional consequences of both kinds of variations. This systematic approach will lay a base for a quantitative description of the effects of pathological and interspecies differences in middle-ear structure on auditory function. Such a description will replace anecdotal descriptions with a comprehensive theory that can impact the clinical understanding of middle-ear pathology and reconstruction as well as ideas about evolution of the ear.