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

componentsBony 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• Scala vestibuli• Scala media• Scala tympani

ORGAN OF CORTI