THE INTERNAL EAR 内耳
The petrous portion of the temporal bone is the densest bone in the body, forming the medial margin of the middle ear. It is an angular, conical bone with its apex pointed rostral and ventral (Fig. 14). Relative to other bones of the skull, the petrous portion of the temporal bone is more yellow and does not contain medullary or marrow compartments. A bony bulge that protrudes lateral and ventral from the petrous temporal bone is referred to as the “promontory.”1,2,8 The basal turn of the cochlea is demarcated by this promontory. The vestibular or oval window and cochlear or round window flank the promontory on opposing sites. Rostrally, a second bulge is present in dogs and cats, denoting the cochlea. Contrary to many textbook diagrams that clearly delineate the membranous labyrinthine spiraled cochlea, bulging saccule and utricle, and looping semicircular canals, in reality these delicate structures are buried within the bony labyrinth of the petrous portion of the temporal bone and are not clearly visible without sophisticated imaging equipment.
颞骨岩部是体内最致密的骨头，形成中耳的内侧缘。它是一个角状圆锥骨，尖端指向吻侧和腹侧(图14)。相对于颅骨的其他骨骼，颞骨岩质部分更呈黄色，不含髓腔或骨髓腔。从颞骨外侧和腹侧突出的骨突出称为“隆突”[1,2,8]，耳蜗的基部回转是由这个隆突划分的。前庭窗或椭圆窗和耳蜗窗或圆窗在隆突的两侧对立位置。在吻侧，犬猫会出现第二个隆起，提示耳蜗。许多教科书上的图表清楚地描绘出膜迷路的螺旋状耳蜗、隆起的球囊和椭圆囊以及环状的半规管，与此相反，实际上这些微妙的结构都埋藏在颞骨岩部的骨迷路中，如果没有精密的成像设备，就无法清晰地看到。
Fig. 14 Petrous portion of the temporal bone, left ear, cat.
图 14. 猫左耳颞骨岩部。
The bone on the right has had the cochlea and promontory opened with the use of bone cutters. The most prominent medial bulge is the promontory (P), flanked by the vestibular or oval window (V), and the cochlear or round window (R). This promontory corresponds to the basal turn of the cochlea (Bc). A rostral bulge corresponds to the spiral cochlea (C). A bony depression (Tm) is the fossa for the tensor tympani muscle. The facial canal (F) is partially opened in these sections. (Courtesy of Dr B.L. Njaa, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK.)
右边的骨头已经用骨切割器打开了耳蜗和隆突。最明显的内侧突起是隆突(P)，两侧是前庭或椭圆窗(V)和耳蜗或圆窗(R)，该隆突与耳蜗基底回转(Bc)相对应。一个吻侧隆起对应于螺旋耳蜗(C)。一个骨凹陷(Tm)是鼓膜张肌的窝。面神经管(F)部分开口于这些结构。
When performing a myringotomy during a deep ear flush, it is important to avoid damaging the promontory and the round and oval windows so as to not induce iatrogenic neurologic complications. It is also important to avoid damaging the ossicles, which are important for the amplification and transmission of sound waves to the internal ear.
当在深耳冲洗中进行鼓膜切开术时，避免损害岬隆突和圆窗和椭圆窗以免引起医源性神经系统并发症是极其重要的。避免损伤听小骨也很重要，听小骨对于声波的放大和向内耳的传播很重要。
Because the oval and round windows are located on the dorsal and caudal aspect of the promontory, respectively, the promontory is located opposite to the mid-dorsal aspect of the tympanic membrane, and the ossicles are located dorsorostrally, the myringotomy should be performed in the caudoventral quadrant of the tympanic membrane.
因为椭圆窗和圆窗分别位于隆突背侧和尾侧，隆突位于鼓膜的对侧到背内侧，听小骨位于背吻侧，所以鼓膜切开术应该在鼓膜后腹侧第四象限内进行。
The two main functional units of the internal ear are the auditory system and the vestibular system.44 The former provides a sense of hearing; the latter a sense of balance. The internal ear portion of the auditory system comprises the cochlea and associated cochlear branch of the vestibulocochlear nerve and its connections to the central nervous system. The vestibular system comprises several fluid-filled, epithelial-lined compartments (saccule, utricle, and semicircular canals), which continually provide input to the brain regarding head and body orientation and direction and speed of movement.
内耳的两个主要功能单元是听觉系统和前庭系统。[44]前者提供听觉;后者提供平衡感。听觉系统的内耳部分包括耳蜗和前庭耳蜗神经的耳蜗分支及其与中枢神经系统的连接。前庭系统由几个充满液体、内衬上皮细胞的腔室(球囊、椭圆囊和半规管)组成，这些腔室持续向大脑提供有关头部和身体方向、运动方向和速度的输入信号。
THE COCHLEA 耳蜗
The cochlea is the highly coiled series of fluid-filled compartments. The two main compartments include the scala vestibuli and the scala tympani, both containing perilymph, a distillate of cerebrospinal fluid. At the apex of the cochlea both scala are in direct communication by the helicotrema.1,2,4,49,50 Sandwiched between these two scala is the much smaller fluid-filled scala media or cochlear duct (shown in the articles by Ryugo and Strain elsewhere in this issue). The scala media is separated from the scala vestibuli by the vestibular membrane (Reissner’s membrane) and from the scala tympani by the basilar membrane (shown in the article by Ryugo elsewhere in this issue). These three compartments spiral 2.5 turns about a central axis known as the “modiolus,” through which runs the cochlear nerve.1,2,4,49,50
耳蜗是高度卷曲的一系列充满液体的腔室。两个主要的腔室包括前庭阶和鼓阶，两者都含有外淋巴，外淋巴是脑脊液的馏出物。在耳蜗的顶端，两个阶通过蜗孔直接相连。[1,2,4,49,50]夹在这两个阶之间的是更小的充满液体的中阶或蜗管。中阶被前庭膜从前庭阶(瑞斯纳膜 )分离，被基底膜从鼓阶分离。这三个螺旋绕着被称为“耳蜗轴”的中轴旋转2.5圈，耳蜗神经通过该中轴。[1,2,4,49,50]
Atop the basilar membrane is the organ of Corti, the sensory or spiral organ of hearing. The sensory cells are called hair cells, denoted as inner hair cells and outer hair cells, relative to a central modiolus point of reference. A gelatinous, collagen containing tectorial membrane is suspended over the organ of Corti, in which hair cells are apically embedded. The hair cells receive afferent and efferent innervation from the cochlear branch of the vestibulocochlear nerve (cranial nerve VIII).44,49,50
基底膜顶上是螺旋器/科蒂氏器官，即听觉得感受或者螺旋器官。感觉细胞称为 毛细胞，相对于中央耳蜗轴为参照点，分为内毛细胞和外毛细胞。一种胶质的，含胶原的幕膜悬吊在科蒂氏器官的上方，毛细胞在顶端嵌入其中。毛细胞接受前庭耳蜗神经(脑神经VIII)的耳蜗支的传入和传出神经支配。[44,49,50]
Hair cells are not neurons but are cellular mechanoreceptors with apical sensory “hairs” that are not pilosebaceous units but highly specialized stereocilia and kinocilia. Fluid pressure waves in the scala vestibuli from vibrations from the stapes result in deflection of the basilar membrane of the scala media. This results in movement of the organ of Corti and the tectorial membrane perched on the apical cilia of hair cells causes them to bend. The direction these apical cilia bend determines if the cell becomes depolarized or hyperpolarized. Depolarized hair cells release neurotransmitter across its basolateral margin at synapses with neurons of the cochlear nerve, whereas hyperpolarization of the cell inhibits neurotransmitter release. Along its length, the basilar membrane varies from narrow and thick to wide and thin, thereby enabling detection of various frequencies along its entire length (shown in the article by Ryugo elsewhere in this issue).44,49,50
毛细胞不是神经元，而是具有顶端感觉“毛发”的细胞机械感受器，“毛发”不是毛囊皮脂腺单位，而是高度特化的静纤毛和 动纤毛。来自镫骨振动的前庭阶的流体压力波导致了中阶基底膜的偏斜。这导致了科蒂氏器官的运动，而栖息在毛细胞顶端纤毛上的幕膜使它们弯曲。这些顶端纤毛弯曲的方向决定了细胞是去极化还是超极化。去极化的毛细胞通过其基底外侧边缘与耳蜗神经神经元突触 释放神经递质，而细胞的超极化 抑制神经递质释放。基底膜的长度从窄厚到宽薄不等，因此能够探测整个长度的不同频率。[44,49,50]
THE VESTIBULAR SYSTEM 前庭系统
The caudal half to one-third of the petrous portion of the temporal bone contains the vestibular structures, including the saccule, the utricle, and the semicircular canals (shown in the article by Ryugo elsewhere in this issue).1–4,8,49,50 The saccule and utricle are located within the vestibule in close proximity to the stapes and basal turn of the cochlea. Neurosensory epithelial hair cells aggregate in a thickened region of the wall of these endolymph-filled cavities called the macula. The saccular macula is oriented vertically, whereas the uticular macula is oriented horizontally. Overlying each maculae is a gelatinous layer of polysaccharide to which are adhered small calcium carbonate crystals called “otoliths.” Because these otoliths have greater density than endolymph, as the head moves, otoliths under the pull of gravity cause the apical cilia of hair cells to become deflected. In aggregate, the maculae of the utricle and saccule function to detect the steady tilt of the head.44 Semicircular canals branch caudally from the utricle in orthogonal planes. Each canal bulges at its direct connection to the utricle called “ampullae.” Specialized neurosensory structures within the ampullae are called “crista ampularis,” which contain sensory hair cells. Apical cilia from these hair cells are embedded in a gelatinous structure called the cupula. Movement of these cupula relative to their embedded hair cells is how rapid angular acceleration of an animal’s head is detected.44,49,50
颞骨岩尾侧一半至尾侧三分之一处包含前庭结构，包括球囊、椭圆囊和半规管。[1-4,8,49,50]球囊和椭圆囊位于前庭内，靠近镫骨和耳蜗基底回转。神经感觉上皮毛细胞聚集在这些充满内淋巴腔的增厚区域，称为斑。球囊斑是垂直方向的，椭圆囊斑是水平方向的。在每个斑上都有一层胶状多糖层，附着在上面的小碳酸钙晶体被称为“耳石”。由于耳石的密度比内淋巴液大，当头部移动时，耳石在重力的作用下会使毛细胞的顶端纤毛偏斜。总的来说，椭圆囊斑和球囊斑的功能可以检测头部的稳定倾斜。[44] 在直角面半规管从椭圆囊向尾侧分支。每个通道都在与椭圆囊直接连接的位置凸出，称为“壶腹”。壶腹内特殊的神经感觉结构被称为“壶腹嵴”，其中包含感觉毛细胞。这些毛细胞的顶端纤毛嵌在一种叫做 壶腹帽的胶状结构中。这些壶腹帽相对于它们内嵌的毛细胞的运动可以检测到动物头部的角度加速度。[44,49,50]
SUMMARY 总结
The ear is often thought of as pinnae and associated structures. The pinnae and associated dermis is a direct extension of the epidermis and dermis of the body and may be a predilection site for various dermatologic entities. The middle ear is a bony encased, air-filled chamber whose only connection to ambient air is through the auditory tube. Within this cavity are three crucial bones, the auditory ossicles, which transduce air pressure changes in the tympanic membrane to fluid waves in the internal ear acting as an impedance matching device. Specialized neurosensory epithelium within the cochlear portion of the membranous labyrinth of the internal ear convert these fluid waves into action potentials that are transmitted to the brain by the cochlear nerve for recognition as sound. Variation in the width and density of the basilar membrane of the scala media mediates variable recognition of various sound frequencies. Similar neurosensory epithelium in the vestibular portions of the internal ear similarly respond to steady and rapid acceleration movements of the head to maintain balance and normal proprioception by signals traveling through the vestibular branch of the vestibulocochlear nerve. Therefore, numerous loci within this complex sensory organ can become dysfunctional. Recognition of clinical disease necessitates a “sound” understanding of otic anatomy and physiology and keen observation skills.
耳朵通常被认为是耳廓和相关的结构。耳廓和相关真皮是身体表皮和真皮的直接延伸，可能是各种皮肤疾病的易感部位。中耳是一个被骨质包裹的充满空气的腔体，它与周围空气的唯一连接是通过耳咽管。在这个洞内有三个重要的骨头，即三块听小骨，它们将鼓膜内的气压变化转化为内耳的流体波，作为一个阻抗匹配装置而起作用。内耳膜迷路耳蜗部分的特殊神经感觉上皮将这些液体波转化为动作电位，通过耳蜗神经传递到大脑以识别声音。基底膜宽度和密度的变化介导了对不同频率声音的识别。在内耳前庭部分类似的神经感觉上皮也同样对头部稳定和快速的加速运动作出反应，以通过前庭耳蜗神经的前庭分支来维持平衡和正常的本体感受。因此，在这个复杂的感觉器官中的许多轨迹可以变得功能失调。对临床疾病的认识需要对解剖学和生理学有“完全的”理解和敏锐的观察技能。
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发表于 2021-2-12 18:10:55
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