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VESTIBULOCOCHLEAR APPARATUS. Dr Iram Tassaduq. introduction. Ear is related to equilibrium and hearing Consist of 3 parts external ear for sound wave reception middle ear for transmission of bones from air to bone
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VESTIBULOCOCHLEAR APPARATUS Dr Iram Tassaduq
introduction • Ear is related to equilibrium and hearing • Consist of 3 parts external ear for sound wave reception middle ear for transmission of bones from air to bone inner ear for transduction of vibrations to nerve impulses
EXTERNAL EAR • Pinna having elastic cartilage • External auditory meatus having coiled tubular glands • Tympanic membrane covered externally by epidermis and internally by simple cuboidal epithelium
MIDDLE EAR • Lined by simple squamous epithelium • Thin lamina propria • Transformation of simple squamous to pseudostratified ciliated columnar epithelium near auditory tube
INTERNAL EAR • Has two components Bony labyrinth consist of cochlea,vestibule and semicircular canals Membranous labyrinth consist of saccule and utricle filled with endolymph
MEMBRANOUS LABYRINTH • Composed of thin sheet of connective tissue lined with simple squamous epithelium • Have maculae ( regions of differentiated neuroepithelial cells)
STRUCTURE OF MACULA • 2 types of receptor (hair cells) • Supporting cells are columnar in shape with microvilli • Otolith a gelatinous glycoprotien covering this neuro epithelium
ENDOLYMPHATIC DUCT AND SAC • Endolymphatic duct is lined by simple squamous epithelium initially • Simple columnar epithelium near sac
COCHLEAR DUCT • Divided into 3 spaces • Scalavestibuli • Scala media • Scala tympani