Tunica Albuginea, Lateral View

Description

Cut in cross-section, the hair follicle forms a long epithelial cylinder extending from the epidermis into the dermis, surrounding the central hair shaft and its root. A lateral profile emphasizes the follicular wall and its outer coverings, including the external root sheath continuous with the epidermis and the surrounding connective tissue sheath in the perifollicular dermis. Deep in the follicle, the hair bulb expands around the dermal papilla, where capillaries and fibroblasts sit directly inferior to the matrix cells that generate the growing hair. A short oblique arrector pili muscle inserts on the follicle and runs superficially toward the papillary dermis, while the sebaceous gland opens into the follicular canal superior to the bulb. This lateral section matters because it clarifies where common hair and pilosebaceous disorders start and spread: acne vulgaris and folliculitis track along the follicular infundibulum and isthmus, while alopecia areata targets the bulb region around the dermal papilla. The relationship between sebaceous duct, follicular canal, and arrector pili also explains why piloerection and sebum delivery depend on an intact pilosebaceous unit, and why surgical excision of an epidermoid (infundibular) cyst must remove the entire cyst wall derived from follicular epithelium. Clear landmarks. Cleaner clinical reasoning. Use this artwork in dermatology and integumentary system teaching to distinguish internal versus external root sheath layers, to map the hair growth cycle to the bulb and papilla, or to annotate the anatomy involved in laser hair removal and follicular unit transplantation. It also fits well in patient-facing education on folliculitis, sebaceous activity, and hair loss mechanisms where a precise, labeled section prevents the usual confusion between hair shaft and follicle. Anatomical accuracy verified by SciePro's Medical Advisory Board.