What is Inner part (medulla)?

The medulla is the soft, inner layer of your hair strand that holds everything together like a busy hallway deep inside a castle tower. Just as you have bones in the center of your body to give it structure, every single hair has this tiny core running up its middle. It is made of loosely packed cells and air spaces, which makes it feel spongy if you could squish one between your fingers.

Think of the medulla like the filling in a chocolate bar. The outer part of your hair (the cuticle) is like the smooth wrapper that protects everything. But inside, the medulla acts as a support beam. It helps keep the hair strong so it doesn’t snap when you brush it. Without this inner core, your hair would be more like a fragile thread than a sturdy rope.

The medulla isn't present in all hairs and can look different depending on how much air is trapped inside. Some people have continuous stripes of medulla, while others have it broken up like puzzle pieces.

The medulla helps your hair keep its shape and color intensity. Because it contains fewer pigment granules than the outer layer, it can make darker hairs look even richer by reflecting light differently. When you see a magnified view of thick animal fur or coarse human hair, that fuzzy white stripe down the center is often the medulla. It works quietly every day to support the hardworking layers around it, ensuring your hair stays healthy and resilient against daily wear and tear.