Category Archives: General Health

Clinical Examination for Ear Disease

Clinical Examination of the Ear Equipment for Ear Examination Both indirect and direct light sources are used 1. Bull’s eye lamp-indirect light source. 2. Head mirror. 3. Head light-direct light source. 4. Ear specula of various sizes-The largest speculum which can be conveniently inserted into the ear canal should be used. 5. Siegel’s pneumatic speculum.… Read More »

History Taking for Ear Infections

HISTORY TAKING History taking and careful clinical examination is very much essential to establish a proper diagnosis. No amount of present day sophisticated investigations can replace thorough history taking and careful clinical examination. History taking for ear diseases can be described under the following headings: • Chief complaints • History of presenting symptoms • Past… Read More »

Vestibular System- Mechanism and Functions

It was Mach in 1875 that identified the role of the vestibular apparatus in the perception of motion. This consists of functional subdivisions – Semicircular canals-Sense of head rotation. Otolith organs-Stimulated by gravity and linear acceleration of the head. Physiologically, the vestibular labyrinth transduces mechanical energy (linear and angular) into electrical activity (nerve action potential)… Read More »

Theories of Hearing

Theories of Hearing • Helmhotz’s place theory (1883): postulated that the basilar membrane acts as a series of tuned resonators similar to a piano string. Each pitch would cause resonant vibration of the basilar membrane which is particular to its own place. Thus, the frequency was analyzed. High frequency waves excite the basal region and… Read More »

Ear Physiology

When sound signal strikes the tympanic membrane, the vibration is transmitted to the stapes footplate through a chain of ossicles. The movements of the stapes causes pressure changes in the labyrinthine fluids which move the basilar membrane. This stimulates the hair cells of the organ of corti which acts as a transducer. MECHANISMS OF HEARING… Read More »

Inner Ear Anatomy- Development and Relationship

Development It starts in the 3rd week of the intrauterine life and is completed by the 16th week of the intrauterine life. Membranous labyrinth develops from the otic capsule. This differentiates into various structures, like sensory end organ of hearing and equilibrium. Bony labyrinth develops from the otic capsule. This is a mesenchymal condensation surrounding… Read More »

Middle Ear-Anatomy and Development

Structures of Tympanic Cavity The entire middle ear cleft is lined by columnar ciliated and pavement epithelium. It is an exten­ sion of the respiratory mucous membrane from nasopharynx. The middle ear cleft consists of: 1. Eustachian tube 2. Tympanic cavity 3. Mastoid antrum 4. Aditus ad antrum 5. Mastoid air cells. EUSTACHIAN TUBE Eustachian… Read More »

External Ear Anatomy

“Otology is almost unique even ill the later part of the 20th century in not being able to explain at least a few of its diseases ill biochemical terms” – Ruben 1975. Ear is divided into three parts: 1. External ear 2. Middle ear 3. Inner ear It consists of pinna and external auditory canal.… Read More »

Embryology of the Ear

EAR DEVELOPMENT Ear has a very complex source of development. The sound conductive apparatus develops from the branchial apparatus whereas the sound perceptive apparatus develops from the ectodermal otocyst (pars otica). Because of this dual source of origin the developmental anomaly that produced commonly affects either the sound conductive system which includes anomaly of the… Read More »