Meatus external auditory

When a sound pressure wave impinges on the ear, it is amplified by the external auditory meatus and causes the tympanic membrane to vibrate in a characteristic manner. This vibration is transformed by the auditory ossicles of the middle ear into movements of the stapedial footplate. These movements create pressure waves in the fluids of the inner ear which displace the basilar membrane of the cochlear duct and cause the hair cells located on the top of the basilar membrane to generate electrical potentials. This potential elicits impulses in the auditory nerve. After the auditory nerve, the nerve impulses are transmitted through the cochlear nuclei, the trapezoid body, the... 

Hguie 9.40 The ear and its associated structures medications would normally enter only the external auditory meatus. 

As shown in Figure 5.1, ambient sounds are collected by the pinna, the visible portion of the external ear, and guided to the middle ear by the external auditory meatus, or ear canal Sounds are filtered due to the... 

One child (serial no 362) who was mute but not deaf had large perforations of both eardrums and on one occasion pus was observed in the external auditory meatus Initial analysis of the maternal serum relating to this child revealed a reduced FT and considerably elevated TSH although the TT was almost within the normal range. Repeat analysis of the serum confirmed a reduced FT, elevated TSH and normal FT and TT Unfortunately there was insufficient serum remaining to validate the TT value ... 

The knowledge of these segmentation values is extremely important to determine whether or not the reconstructed images correspond to reality. To this end a comparison between real anatomy and 3D reconstructed endoluminal views from seven formalin fixed anatomical specimens was performed by our group (Neri et al. 2000b). We found a 100% agreement between the observations for endoluminal views and anatomical sections, even if in two cases the complete visualization of the middle ear cavity could not initially be obtained for the presence of tissue remnants within the external auditory meatus. However, careful electronic removal of this tissue allowed visualizing the middle ear, while in the case of anatomical specimens, the tissue remnants were manually removed. 

Propylene glycol is a diol (propane-1, 2-diol). It is in use in cutaneous preparations, dissolved in the aqueous phase, as a humectant, to slow down a dehydration process. Other applications are the use as softening agent and as vehicle for ear drops intended for the external auditory meatus (see Sect. 9.5.3). 

The external ear (pinna) and the external auditory meatus form the outer ear. The eardrum, a membrane of connective tissue 0.1 mm thick and 8-10 mm in diameter, divides the external ear from the middle ear. The eardrum acts as a resonator with an inherent frequency of approximately 3000 Hz. The middle ear consists of an air-filled cavity, the... 

The mandibular fossa is an oval depression in the temporal bone just anterior to the external auditory meatus. It is bounded anteriorly by the articular tubercle, laterally by the zygomatic process, and posteriorly by the tympanic plate. The close proximity of the mandibular fossa to the external auditory meatus allows fingers placed in the meatus of each ear to palpate condylar motion as it rotates and glides in the fossa. Occasionally, a small ridge of bone (the postglenoid tubercle) forms a prominence at the posterior border of the fossa. The shape of the mandibular fossa does not exactly conform to the mandibular condyle. The articular disk molds the two surfaces together. 

Palpation of the TMJ through the external auditory meatus, noting tenderness or deviation with motion (Fig. 111-1). 

Deafness, absence or atresia of external auditory meatus 12... 

Incident wave along axis of external auditory meatus significant risk of ear damage... 

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