The central projections of the peripheral cochlear nerve fiber from each turn to the cochlear nuclei (CN) in the mongolian gerbil were investigated using retrograde transportation of horseradish peroxidase (HRP). The organ of Corti and the osseous spiral lamina were scratched with an electrolytically-sharpened fine needle via a small hole at each turn of the cochlea. The cochlea was filled with a 30% horseradish peroxidase (HRP) solution. After 48 hours, 50 microns transverse serial sections of the brainstem were made with a vibratome. The tissue was processed with the diaminobenzidine procedure of the cobalt-glucose method. Our experiment revealed that the fibers from the basal turn terminated at the dorsomedial portion of anteroventral cochlear nuclei (AVCN), but those from the apical turn were distributed among the ventrolateral portion of the AVCN. In the posteroventral cochlear nuclei (PVCN) and dorsal cochlear nuclei (DCN), the fibers from basal to apical turns extend from the dorsal to the ventral portion of each nuclei. A distinct tonotopic arrangement could be found between the origin of cochlear fibers of each turn and their termination in the regions of the cochlear nuclei (CN). Also, the results suggested that the scratch method combined with retrograde transportation of horseradish peroxidase was useful in investigating the tonotopic arrangement of the peripheral auditory nerve in the CN.
Animal ; Cochlear Nerve/*anatomy & histology ; Cochlear Nucleus/*anatomy & histology ; Gerbillinae ; Horseradish Peroxidase ; Nerve Fibers

OBJECTIVE: In order to provide help for preoperative assessment of cochlear implantation, related dissection of temporal bone was conducted guided by high resolution computerized tomography (HRCT) in accordance to the main steps of cochlear implantation, and was compared to HRCT measurements on a viewing workstation. METHOD: Six temporal bones were dissected according to the main steps of cochlear implantation and scanned in axial and semilongitudal planes by HRCT to observe the relationship between anatomy and HRCT. RESULT: The width of facial recess in dissection was (3.13 +/- 0.34) mm at the level of round window, and (4.12 +/- 0.44) mm at the level of oval window. The width of facial recess in HRCT was (3.20 +/- 0.38) mm at the level of round window, and (4.14 +/- 0.47) mm at the level of oval window. The whole course of facial nerve was visualized clearly in semilongitudal plane. No statistically significant differences were found between the results of dissection and HRCT. CONCLUSION The distance in axial between facial nerve and posterior wall of external auditory canal and the distance from facial nerve to round window in semilongitudal plane are the most important parameters which reflect the position of facial nerve. The vertical portion of facial nerve, posterior wall of external auditory canal, round window are important measurement landmarks. Related preoperative measurements of cochlear implantation by HRCT can help to guide clinic surgery.
Child, Preschool ; Cochlear Implantation ; methods ; Cochlear Implants ; Ear Canal ; anatomy & histology ; Facial Nerve ; anatomy & histology ; Humans ; Infant ; Round Window, Ear ; anatomy & histology

OBJECTIVE: To study a new surgical approach for cochlear implantation. METHOD: We operated on 8 cadaver heads (16 side) use Suprameatal approach for cochlear implantation, describe related anatomic mark. RESULT: The electrode is passed through the suprameatal tunnel, the EAC groove, the space underneath the chorda tympani between the malleal and the long process of the incus, and the cochleostomy. Angle between tunnel and temporal imaginary line is 28.0 degrees +/- 1.3 degrees in adult, 29.0 degrees +/- 1.7 degrees in children, the location of inserting electrode into cochleostomy is (1.31 +/- 0.13) mm to round window in adult, (1.19 +/- 0.12) mm in child. CONCLUSION The SMA approach is a safe technique, maintaining a safe distance to facial nerve and chorda tympani. So We should make right decision in clinic.
Adult ; Child ; Chorda Tympani Nerve ; anatomy & histology ; Cochlear Implantation ; methods ; Ear Canal ; anatomy & histology ; surgery ; Facial Nerve ; anatomy & histology ; Humans ; Round Window, Ear ; anatomy & histology

OBJECTIVE: To provide anatomic data for cochlear implantation, and to find the method of locating lamina spiralis (LS) on the surface of promontory. METHOD: Microanatomical study was carried out on 30 sides of human temporal bones by observing and measuring lamina spiralis below promontory, including its location, course and adjacent structures. RESULT: (1) The basal turn of lamina spiralis below promontory can be divided into three segments: the hook segment (1.52 +/- 0.16) mm, the anteroinferior round window segment (3.83 +/- 0.37) mm and the forwarding segment (2.70 +/- 0.36) mm by two hinge points of which one was located at anterior of the junction of superior margin and anterior border of RW, and the other was located at anteroinferior of the round window; (2) The plane of round window anteroinferior segment of LS lay (51.00 +/- 5.97) degrees anteroinferior to horizontal segment of the facial nerve and comparative permanently meet posterior margin of'stapes head. Made posterior margin of stapes head as a fixation point and draw a line on promontory lay (51.00 +/- 45.97) degrees anteroinferior to horizontal segment of the facial nerve. This line can be thought as the projection of anteroinferior round window segment of LS on promontory; (3) The width of scala tympani at cochleostomy site on promontory: width of scala tympani at midpoint of superior margin of round window was (0.36 +/- 0.06) mm; width of scala tympani at midpoint of anterior border of round window was (0.97 +/- 0.14) mm; width of scala tympani at 3 mm point of anteroinferior round window segment was (1.24 +/- 0.21) mm. CONCLUSION (1) The basal turn lamina spiralis below promontory can be divided into three segments (the hook segment, the anteroinferior round window segment and the forwarding segment) by two hinge points; (2) The projection of anteroinferior round window segment of LS and the features exhibited in its course provide reference for locating the basal turn scala tympani and offer reliable anatomical basis for minimal invasive intervention during cochlear implantation.
Adult ; Cochlear Implantation ; methods ; Facial Nerve ; anatomy & histology ; surgery ; Humans ; Round Window, Ear ; anatomy & histology ; surgery ; Scala Tympani ; anatomy & histology ; surgery ; Temporal Bone ; anatomy & histology ; surgery

OBJECTIVE: To investigate the related parameters of temporal bone structure in the surgery of cochlear implantation through facial recess approach so as to offer a theoretical reference for the avoidance of facial nerve injury and the accurate localization. METHOD: In a surgical simulation experiment, twenty human temporal bones were studied. The correlation parameters were measured under surgical microscope. RESULT: Distance between suprameatal spine and short process of incus was (12.44 +/- 0.51) mm. Width from crotch of chorda tympani nerve to stylomastoid foramen was (2.67 +/- 0.51) mm. Distance between short process of incus and crotch of chorda tympani nerve was (15.22 +/- 0.83) mm. The location of maximal width of the facial recess into short process of incus, crotch of chorda tympani nerve were (6.28 +/- 0.41) mm, (9.81 +/- 0.71) mm, respectively. The maximal width of the facial recess was (2.73 +/- 0.20) mm. The value at level of stapes and round window were (2.48 +/- 0.20 mm) and (2.24 +/- 0.18) mm, respectively. Distance between pyramidalis eminence and anterior round window was (2.22 +/- 0.21) mm. Width from stapes to underneath round window was (2.16 +/- 0.14) mm. CONCLUSION These parameters provide a reference value to determine the position of cochlear inserting the electrode array into the scale tympani and opening facial recess firstly to avoid potential damage to facial nerve in surgery.
Anatomic Landmarks ; anatomy & histology ; Chorda Tympani Nerve ; anatomy & histology ; Cochlea ; anatomy & histology ; Cochlear Implantation ; methods ; Ear, Middle ; Facial Nerve Injuries ; prevention & control ; Humans ; Incus ; anatomy & histology ; Organ Sparing Treatments ; methods ; Round Window, Ear ; anatomy & histology ; Stapes ; anatomy & histology ; Temporal Bone ; anatomy & histology ; Tympanic Membrane ; anatomy & histology