4th edition; 1999. p 971. from what they were when they contacted the tympanic membrane, a testament to the amplifying power of the middle ear. It is a reniform (kidney-shaped) opening leading from the tympanic cavity into the vestibule of the internal ear; its long diameter is horizontal and its convex border is upward.
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The overall length of adults is and weight is from making them the same length as the northern walrus but usually less than half the weight.Leopard Seals, Hydrurga leptonyx. marinebio.org The whiskers are short and clear. As "true" seals, they do not have external ears or pinnae, but possess an internal ear canal that leads to an external opening.
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The auditory pit, also known as the otic pit, is the first rudiment of the internal ear. It appears shortly after that of the eye, in the form of a patch of thickened ectoderm, the auditory plate, over the region of the hind-brain. The auditory plate becomes depressed and converted into the auditory pit (or otic pit).
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The coastal Indians in California harvested grunion during spawning runs. Archeologists have found fossil grunion otoliths (tiny, bonelike particles or stony platelike structures in the internal ear of lower vertebrates) at various Indian campsites. Grunion were mentioned by Spanish explorer Juan Rodríguez Cabrillo in his ship's log dated around 1542. Scientists first identified grunion in San Francisco Bay in 1860.
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Opera, 1741 Valsalva both studied and taught in the fields of science, surgery, anatomy, physiology, and psychiatry. At a young age, Valsalva had successfully removed a dog’s kidney. He opposed cauterization in the treatment of wounds, and recommended humanitarian treatment of mentally ill patients. His main interest was the middle and internal ear, including the muscles of the external ear and the pharyngeal muscles.
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Franceschetti–Klein syndrome (also known as "Mandibulofacial dysostosis") is a syndrome that includes palpebral antimongoloid fissures, hypoplasia of the facial bones, macrostomia, vaulted palate, malformations of both the external and internal ear, buccal-auricular fistula, abnormal development of the neck with stretching of the cheeks, accessory facial fissures, and skeletal deformities.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. .
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In Amphisbaenia, the extracolumella is particularly lengthened and firmly connects with a layer of skin over dentary bone of the lower jaw. This connection appears to facilitate detection of airborne vibrations in the facial area. The embedding in the skin often occurs at a specially enlarged labial scale. As a result, the amphisbaenian is able to detect substrate vibrations as it burrows through the ground while protecting the internal ear from damage.
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Whytt explains that the pupillary light reflex is the contractions and re-sizing of the pupil in different intensities of light. If the eye was incapable of contraction, we would only be able to see in one degree of light and we would not be able to differentiate the distance of light reflecting from near and far objects.Whytt, R. (171). Of the Motions of the Pupil and Muscles of the Internal Ear.
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Image of a Vintage Acousticon Hearing Aid By Dictograph Products Company, Made in the US, Circa 1934. Some hearing aids employ bone conduction, achieving an effect equivalent to hearing directly by means of the ears. A headset is ergonomically positioned on the temple and cheek and the electromechanical transducer, which converts electric signals into mechanical vibrations, sends sound to the internal ear through the cranial bones. Likewise, a microphone can be used to record spoken sounds via bone conduction.
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Gabriel Falloppius explaining one of his discoveries to the Cardinal Duke of Ferrara Falloppio's own work dealt mainly with the anatomy of the head. He added much to what was known before about the internal ear and described in detail the tympanum and its relations to the osseous ring in which it is situated. He also described minutely the circular and oval windows (fenestræ) and their communication with the vestibule and cochlea. He was the first to point out the connection between the mastoid cells and the middle ear.
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Asymmetry has not been reported to extend to the middle or internal ear of the owl. Asymmetrical ear placement on the skull allows the owl to pinpoint the location of its prey. This is especially true for strictly nocturnal species such as the barn owls Tyto or Tengmalm's owl. With ears set at different places on its skull, an owl is able to determine the direction from which the sound is coming by the minute difference in time that it takes for the sound waves to penetrate the left and right ears.
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Together the 22 bones that compose the skull form additional, smaller spaces besides the cranial vault, such as the cavities for the eyes, the internal ear, the nose, and the mouth. The most important facial bones include the jaw or mandible, the upper jaw or maxilla, the zygomatic or cheek bone, and the nasal bone. Humans are born with separate plates which later fuse to allow flexibility as the skull passes through the pelvis and birth canal during birth. During development the eight separate plates of the immature bones fuse together into one single structure known as the Skull.
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The vestibulocochlear nerve is accompanied by the labyrinthine artery, which usually branches off from the anterior inferior cerebellar artery (AICA) at the cerebellopontine angle, and then goes with the 7th nerve through the internal acoustic meatus to the internal ear. The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia. Processes from the organ of Corti conduct afferent transmission to the spiral ganglia. It is the inner hair cells of the organ of Corti that are responsible for activation of afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound.
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His interest since that time was mainly the physics of the auditory system. There, he was the first to demonstrate physiologically that the innervation of the tensor tympani muscle was by the trigeminal nerve and that the innervation of the stapedial muscle was by the facial nerve. In another series of experiments, Politzer connected two manometers, one placed in the external auditory canal meatus and another in the pharynx, in order to study air movements through the Eustachian tube. In 1861, he published his first results on a new technique based on this knowledge, to treat internal ear diseases by insufflating the middle ear through the Eustachian tube, which obviated the need of its catheterization.
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An outstanding example of the physician–humanist, Cotugno was devoted to books and accumulated a large library, was well versed in art, architecture, numismatics, and antiquities, and had a great facility in the Latin language. In 1761 Cotugno published for distribution to friends a plate that traced the course of the nasopalatine nerve, which is responsible for sneezing. Antonio Scarpa acknowledged his priority in knowledge of this nerve. In the same year his anatomical dissertation De aquaeductibus auris humane internae, following the work of Guichard Joseph Duverney and Antonio Maria Valsalva and anticipating that of Hermann von Helmholtz, described the vestibule, semicircular canals, and cochlea of the osseus labyrinth of the internal ear, demonstrated the existence of the labyrinthine fluid, and formulated a theory of resonance and hearing.
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Like the mastoid cells, it is filled with air and lined by a prolongation of the mucous membrane of the tympanic cavity, with which it communicates. The tympanic antrum is bounded above by a thin plate of bone, the tegmen tympani, which separates it from the middle fossa of the base of the skull, below by the mastoid process, laterally by the squama just below the temporal line, and medially by the lateral semicircular canal of the internal ear, which projects into its cavity. It opens in front into that portion of the tympanic cavity which is known as the attic or epitympanic recess. The tympanic antrum is a cavity of some considerable size at the time of birth; the mastoid air cells may be regarded as diverticula from the antrum and begin to appear at or before birth.
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