MSB and LSB in floating point number
In the whole floating point number the MSB is a sign bit and LSB is in the mantisa (last bit).

In all floating point formats with exception of 10 byte IEEE real the mantissa MSB of normalised number is not stored because it is implicitly set to $1$ (and used in calculations).

So in the case of your significand (mantissa) $0011010000$ the MSB is $1$ (implicit) and LSB is $0$ (explicit).