Which part of the cell membrane is hydrophobic?

The interior portion of the cell membrane that is not exposed to the inner cytoplasm or the extracellular matrix is hydrophobic. Phospholipid molecules, which are composed of a hydrophilic head and two hydrophobic tails, make up the major component of the cell membrane. The heads are arranged in such a way as to form a hydrophilic outer lining facing the extracellular matrix and a hydrophilic inner lining facing the aqueous cytoplasm. The tails lie sandwiched in between the outer and inner lining, creating a hydrophobic interior region. Water is attracted to the surfaces of the membrane but is unable to pass through the hydrophobic interior layer.