What is the alternative name for the external sheath of a hair follicle?

The alternative name for the external sheath of a hair follicle is known as the dermal root sheath. This structure plays an essential role in the hair follicle's anatomy and function. The dermal root sheath is composed of connective tissue and surrounds the hair follicle, providing support and protection. It also plays a role in the attachment of the hair follicle to the surrounding dermis.

Understanding the function of the dermal root sheath is crucial for comprehending how hair grows and the overall health of the hair follicle. It is involved in the nourishment of the hair by housing blood vessels that supply nutrients. Additionally, the term 'dermal' refers to its origin in the dermis layer of the skin, indicating the relationship between the hair follicle and the skin layers.

The other terms mentioned do not accurately refer to the external sheath surrounding the hair follicle. The follicular sheath typically relates to the entirety of the hair follicle structure rather than just the dermal part, while the epidermal layer refers to the outermost layer of skin and does not specifically denote the sheath surrounding the hair follicle. The term external membrane is too vague and not specific to the anatomical structure of the hair follicle.