Are you finding difficulty with understanding the structure of cochlea???

Are you finding difficulty with understanding the structure of cochlea??? 

         Hello everyone most of the students feel difficult to understand the structure of cochlea ,as we know that cochlea is a structure which is most important in hearing .Just imagine, you have a stick(nothing but conical bone called as MODULUS) and you wrapped tube closed at one end, around it .This is the basic structure of cochlea, isn't it?

Ear

        Now, I will go just somewhat deep into the concept .Firstly ,I will say that the wrapping of a tube in the conical form, then I will say around that wrapping there is a hard substance covering it Here in case of cochlea it is a bone now I will say that the tube which is wrapped around the stick here in case of cochlea, módulus, there is no any space in between. 

       Now suppose, the tube has one horizontal flap which is not complete throughout diameter of the tube at the outermost margin of the flap it divides into three flap upper middle and lower the upper and lower flaps terminate into lateral most wall of the tube open the middle flap just remain suspended below the middle flap and over the lower flap there is some structures which have sensory processes now we will merge all this thing into the structure of cochlea the stick which we have mentioned previously is nothing but the conical bone called as modulus inside the modulus there are fibres of the cochlear nerves they branch and innovate the organ of corti the Bony covering which we have mentioned order provides a canal for the membranous tube the upper flap which we have mentioned is nothing but Resseiner's membrane. The lower flap which we have mentioned is nothing but basilar membrane And The Slap in between them is nothing but tectorial membrane this is just suspended over the structure called as hair cells .There are two group of cells -one are outer hair cells and other are inner hair cells. Outer hair cells are in row of 3 while the inner hair cells are in row of one. 

In between the outer and inner hair cells there are cells which support them called as supportive cells .

Cochlea (in cross section) 

         The hair cells possesses stereocilia which get rubbed towards the tectorial membrane and then sound perception happens. There are three compartments of the tube developed due to the upper and lower flaps of the membrane that is nothing but Resseiner's membraneand basilar membrane the upper compartment is called as SCALA VESTIBULIE I while the lower compartment is called as SCALA TYMPANIE and the middle compartment is called as SCALA MEDIA. The hair cells and supportive cells which together form organ of corti are located in the middle compartment that is nothing but scala media .The middle compartment not present throughout the tube ,it got terminated by fusion of of  Resseiner's membrane and basilar membrane thereby bhai the upper compartment called as scala  vestibulie and lower compartment called as scalar tympanie get fused to form continuous tube .Thhe fusion point is called as  HELICOTREMA. The upper compartment is filled with perilymph which is continuous throughout the lower compartment also ,while the the middle compartment called as scalar media contain the fluid called as endolymph .

           According to the basic knowledge we know that Scala vestibulie opens into oval window which is guarded by footplate of stepis  Bone, while the lower compartment called scala tympani

Is garded by round window . When the footplate of stepis  Bone get vibrated ,the vibrations get transmitted into the 

Perilymph of scala vestibulieand these vibrations after passing through helicotrema into the perilymph of scala tympani.vibrations in the  scala tympani  causes vibrations of basilar membrane which cause rubbing of hair cells towards the tectorial membrane and impulse generated through it, which is transmitted through cochlear nerve.