The inner root sheath or internal root sheath of the hair follicle is located between the outer root sheath and the hair shaft.[1] It is made of three layers: Henle's layer, Huxley's layer, and the cuticle.[2] The inner root sheaf serves to protect growing hair. [3]
The Inner Root Sheath and the Men Associated with it Eponymically
was invoked but never defined (see the help page).