The root hair plexus is a collection of nerves that surrounds the base of each hair on a human body, according to Education Portal. The root hair plexus allows humans to feel the movement of a single hair, such as when a bug lands on someone's arm.
This bundle of nerves encompasses the bulb, a section of hair that causes it to grow. The root hair plexus is part of the sensory network associated with the integumentary system of the skin. The nerves are near muscle fibers called arrector pili, which are very tiny muscles that allow hairs to stand up straight when the skin gets too cold, notes Education Portal.
The root hair plexus responds to external stimuli at the cellular level, explains class notes from Austin Peay State University. The nerves detect movements of the hair shaft, such as when an object gets close to the skin or when wind occurs.
The root hair plexus surrounds the follicle and connects to larger nerves in the dermis, or lower layer, of skin, according to class notes from Midland Technical College. This bundle of nerves is one of three fine touch receptors in the skin, along with Meissner’s corpuscles and Merkel disks. Meissner's corpuscles and Merkel disks are closer to the boundary between the epidermis and the dermis, whereas root hair plexuses are lower.