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Anatomy and Physiology of Hearing
Published in R James A England, Eamon Shamil, Rajeev Mathew, Manohar Bance, Pavol Surda, Jemy Jose, Omar Hilmi, Adam J Donne, Scott-Brown's Essential Otorhinolaryngology, 2022
Ananth Vijendren, Peter Valentine
The efferent auditory pathway arises from projections from both the lateral olive and the medial olivary complex, which synapse mostly with type 1 and 2 spiral ganglion cells, respectively, and thus connect to both the IHCs and the OHCs. The efferent fibres are carried by the inferior vestibular nerve and meet at the anastomosis of Oort through the saccular branch of the nerve to join up with the cochlear nerve, forming the vestibulocochlear nerve. The cochlear nerve traverses the internal auditory canal (IAC), which is roughly 1 cm in length and its contents are shown in Figure 1.4.
Patient Assessment
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
The skull base lies along a diagonal line running from the mastoid to the eye. Consequently, the signs of a fracture are also found along this line (Box 6.6). Because Battle’s sign and ‘panda eyes’ usually take 12–36 hours to appear, they are of limited use in the resuscitation room. A cerebrospinal fluid (CSF) leak may be missed as the CSF is invariably mixed with blood but should be suspected if clinical signs are present. This should preclude examination of the external auditory canal because of the risk of meningitis. As there is a small chance of a nasogastric tube passing into the cranium through a base of skull fracture, these tubes should be passed orally when this type of injury is suspected.
Anatomy of the Skull Base and Infratemporal Fossa
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
Superolateral to the emerging carotid artery at the apex, the bony Eustachian tube connects to its cartilaginous portion, itself lodged between the greater wing of sphenoid and the petrous apex (see Figure 98.1). It is in reverse proportions to the external auditory canal: the lateral third (around 1 cm long) is bony within the petrous bone, originating from the anterior mesotympanum (middle ear); the medial two-thirds is cartilagenous. This transition from bone to cartilage – the isthmus – marks the Eustachian tube’s narrowest point. Angled forwards, inferiorly and medially at around 30 degrees and 45 degrees respectively, the cartilaginous portion grooves the posterior border of the medial pterygoid plate before opening into the nasopharynx, as described above.
Occlusion and coupling effects with different earmold designs – all a matter of opening the ear canal?
Published in International Journal of Audiology, 2023
Florian Denk, Thomas Hieke, Malte Roberz, Hendrik Husstedt
Two sets of ear impressions were taken from each subject, with the mouth either wide open or closed, in order to be able to later identify the location of the mandibular condyle within the cartilaginous part of the auditory canal (Voogt 2013). All impressions exceeded the second bend of the ear canal. The impressions were then 3 D-scanned, and individual earmolds designed using the Software SecretEarDesigner 5.1 (Cyfex, Zurich, Switzerland). Although the earmolds were designed for coupling a standard sound tube (outer diameter: 3.1 mm, inner diameter: 2 mm), the designs and results from this study are transferable to other earmolds or In-Ear hearing device styles as well. Besides the 3.1 mm bore for the sound tube and the vent, the earmolds included an additional bore of 1.2 mm in diameter for later insertion of a probe tube. This bore was included to avoid additional leaks between skin and earmold by guiding the probe tube along the ear canal wall (Dillon 2012). Its diameter was chosen minimal, while still allowing smooth insertion of the probe tube. The bores for the probe tube and sound tube were placed identically in all earmolds of one subject. The earmolds were designed in the order given below by subsequent “removal” of material. Samples of all earmold designs are shown for one male subject in Figure 1, and STL files of all earmolds and ear canal scans are provided as supplementary material (see Data Availability Statement).
Effects of vaginal birth versus caesarean section on hearing screening results in a large series from the Aegean region
Published in International Journal of Audiology, 2020
Fatih Oghan, Ali Guvey, Muhammet Fatih Topuz, Onur Erdogan, Huri Guvey
We retrospectively analysed the outcomes of hearing screening tests for 10,767 infants born (4723 (43.9%) of them with VB and 6044 (56.1%) of them with CS) between January 2012 and January 2017 in a university hospital in the Aegean region in Turkey. The neonates were divided into two groups according to delivery technique, i.e. the CS and VB groups. Information about delivery techniques, gestational age, birth weight and neonatal hearing screening test results were obtained from their charts. Healthy neonates born in a rural Aegean area who underwent hearing screening tests at our hospital were included in the study. Tests were performed after cleaning the external auditory canal, as the presence of liquid and cerumen could adversely affect the test results. Hearing screening was performed before neonates were discharged.
Outcomes of the Baha Attract System combined with auricle reconstruction in mandarin speaking patients with bilateral microtia-atresia
Published in Acta Oto-Laryngologica, 2019
Xinmiao Fan, Yu Chen, Xiaomin Niu, Yibei Wang, Yue Fan, Xiaowei Chen
In this study, seven patients with bilateral microtia-atresia underwent Baha Attract System implantation and auricle reconstruction simultaneously, whereas the other four underwent Baha Attract System implantation before the auricle reconstruction. In treating patients undergoing implantation before auricle reconstruction, sufficient space should be left for possible future auricle reconstruction. In treating patients undergoing implantation at the same time as the second stage of auricle reconstruction, the implant site should be designed to ensure that the magnet is not placed over the edge of the transplanted flap. In this study, all of the site in all patients was marked at a distance of approximately 7 cm from the external auditory canal, whereas, in normal patients, it can be at 5–7 cm. Both surgical procedures showed positive surgical and audiological results.