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Ear: The hearing and equilibrium system of the body. It consists of three parts: the External ear, the Middle ear, and the Inner ear. Sound waves are transmitted through this organ where vibration is transduced to nerve signals that pass through the Acoustic nerve to the Central nervous system. The inner ear also contains the vestibular organ that maintains equilibrium by transducing signals to the Vestibular nerve.

Ear Exam

JoVE 10148

Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

This video describes the examination of the ear, beginning with a review of its surface and interior anatomy (Figure 1). The cartilaginous auricle consists of the helix,…

 Physical Examinations II

Cereal Crop Ear Counting in Field Conditions Using Zenithal RGB Images

1Plant Physiology Section, Faculty of Biology, University of Barcelona, 2Agrotecnio, 3Programa de Ingeniería Electrónica, Facultad de Ingeniería, Universidad de Ibagué, 4Instituto Tecnológico Agrario de Castilla y León (ITACyL), 5Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 6Syngenta Spain

JoVE 58695


A Comparative Study of Drug Delivery Methods Targeted to the Mouse Inner Ear: Bullostomy Versus Transtympanic Injection

1Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM, 2Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), 3Instituto de Investigación Sanitaria La Paz (IdiPAZ), 4Facultad de Veterinaria, Universidad Complutense de Madrid, 5Departmento de Otorrino laringología, Hospital Universitario La Paz

JoVE 54951



JoVE 10853

When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.

Sound waves are collected by the external ear and amplified as they travel through the ear canal. When sounds reach the junction between the outer and middle ear, they vibrate the tympanic membrane—the eardrum. The resulting mechanical energy causes the attached ossicles—a set of small bones in the middle ear—to move. The ossicles vibrate the oval window, the outermost part of the inner ear. In the labyrinth of the inner ear, the sound wave energy is transferred to the cochlea—a coiled structure in the inner ear—causing the fluid within it to move. The cochlea contains receptors that transduce mechanical sound waves into electrical signals that can be interpreted by the brain. Sounds within the hearing range vibrate the basilar membrane in the cochlea and are detected by hair cells on the organ of Corti, the site of transduction. Along the primary auditory pathway, the signals are sent through the auditory nerve to the cochlear nuclei in the brainstem. From here, they travel to the inferior colliculus of the midbrain and up to the thalamus, and then to the primary auditory cortex. Along this pat

 Core: Biology

Rodent Identification I

JoVE 10189

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN

A fundamental requirement of biomedical research is the proper identification of research animals. It is essential that the right animal is utilized for procedures and data collection. Laboratory mice and rats can be identified with the…

 Lab Animal Research

Preparing and Administering Topical Medications

JoVE 10259

Source: Madeline Lassche, MSNEd, RN and Katie Baraki, MSN, RN, College of Nursing, University of Utah, UT

Topical medications are applied directly to the body surfaces, including the skin and mucous membranes of the eyes, ears, nose, vagina, and rectum. There are many classes of topical medications, such as creams, ointments, …

 Nursing Skills

Cranial Nerves Exam II (VII-XII)

JoVE 10005

Source:Tracey A. Milligan, MD; Tamara B. Kaplan, MD; Neurology, Brigham and Women's/Massachusetts General Hospital, Boston, Massachusetts, USA

The cranial nerve examination follows the mental status evaluation in a neurological exam. However, the examination begins with observations made upon greeting…

 Physical Examinations III

The Vestibular System

JoVE 10856

The vestibular system is a set of inner ear structures that provide a sense of balance and spatial orientation. This system is comprised of structures within the labyrinth of the inner ear, including the cochlea and two otolith organs—the utricle and saccule. The labyrinth also contains three semicircular canals—superior, posterior, and horizontal—that are oriented on different planes. All of these structures contain vestibular hair cells—the sensory receptors of the vestibular system. In the otolith organs, the hair cells sit beneath a gelatinous layer called the otolithic membrane, which contains otoconia—calcium carbonate crystals—making it relatively heavy. When the head is tilted, the otolithic membrane shifts, bending the stereocilia on the hair cells. In the semicircular canals, the cilia of the hair cells are contained within a gelatinous cupula, which is surrounded by endolymph fluid. When the head experiences movements, such as rotational acceleration and deceleration, the fluid moves, bending the cupula and the cilia within it. Similar to the auditory hair cells, displacement towards the tallest cilium causes mechanically-gated ion channels to open, depolarizing the cell and increasing neurotransmitter release. Displacement towards the shortest cilium hyperpolarizes the cell and decreases neurotr

 Core: Biology

The Cochlea

JoVE 10855

The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.

The basilar membrane extends from the basal end of the cochlea near the oval window to the apical end at its tip. Although the cochlea itself narrows towards the apical end, the basilar membrane has the opposite geometry—becoming wider and more flexible towards the apical end. Primarily because of these physical characteristics, the apical end of the basilar membrane maximally vibrates when exposed to low-frequency sounds, while the narrower, stiffer basal end maximally vibrates when exposed to high frequencies. This gradient of frequency response creates tonotopy—a topographic map of pitch—in the cochlea. The hair cells are stimulated by the shearing force created by the vibration of the basilar membrane below them, relative to the stiffer tectorial membrane above them. Because of the tonotopy of the basilar membrane, hair cells are maximally stimulated by different frequencies depending on where they are in the cochlea. Those at the basal end respond be

 Core: Biology


JoVE 10780

Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause Waardenburg Syndrome Type 4, or WS4, which can cause defects in pigmentation, hearing impairments, and an absence of intestinal contractions necessary for elimination. This diversity of phenotypes results from the expression pattern of SOX10 in early embryonic and fetal development. SOX10 is found in neural crest cells that form melanocytes, which are involved in pigmentation and also in the early development of the ear. SOX10 is also expressed in nerve tissue that eventually contributes to the enteric nervous system in the gut, which controls the contractions necessary for waste elimination. In this way, SOX10 exhibits pleiotropic effects, because it influences multiple phenotypes. Pleiotropy can arise through several mechanisms. Gene pleiotropy occurs when a gene has various functions due to encoding a product that interacts with multiple proteins or catalyzes multiple reactions. For example, in humans, an abnormal copy of the SOX10 gene, in which a region is deleted, can lead to developmental defects that include a white forelock, different-colored irises (e.g., one blue and one brown), and regions of unpigmented skin. These traits are all symptoms of a di

 Core: Biology
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