Bald people unequivocally still have a scalp. The scalp is a distinct anatomical structure covering the top of the skull, and its existence is independent of hair presence. Losing hair through pattern baldness simply exposes the underlying skin and tissue that has always been there. The scalp’s primary function involves protecting the cranium and providing necessary vascular and neural support. This structure remains intact even after hair follicles stop producing thick, visible hair.
What Exactly Is the Scalp?
The scalp is composed of five distinct layers of soft tissue lying over the bony skull. The outermost layer is the skin, which is some of the thickest found on the human body. Beneath the skin is a dense layer of connective tissue richly supplied with blood vessels and nerves. This high density of blood supply is why head injuries often bleed profusely.
The third layer is the aponeurosis, a broad, flat tendon connecting muscles at the front and back of the head. Below this is the loose areolar connective tissue, which allows the upper layers of the scalp to move freely over the skull. The deepest layer is the pericranium, a tough, fibrous membrane that tightly adheres to the outer surface of the skull bone. These five tissue layers persist regardless of a person’s hair growth status.
The Science of Follicle Miniaturization
The cause of common baldness, known as androgenetic alopecia, is follicular miniaturization. This process occurs in individuals genetically predisposed to have hair follicles sensitive to dihydrotestosterone (DHT). DHT is a potent androgen, converted from testosterone by the enzyme 5-alpha reductase.
When DHT binds to susceptible hair follicles, it triggers a progressive shortening of the anagen, or growth, phase of the hair cycle. Normally, the anagen phase lasts several years, allowing hair to grow long and thick. Under DHT’s influence, this growth phase becomes shorter with each successive cycle.
Over time, robust terminal hairs are replaced by finer, shorter, and less pigmented vellus hairs. The follicle does not disappear from the scalp tissue; it simply shrinks in size, remaining embedded within the dermis and subcutaneous layers. This structural change means the hair-producing machinery is severely diminished, leading to the visual appearance of hair loss.
The Unique Nature of Bald Scalp Skin
Once the protective canopy of terminal hair is lost, the exposed scalp skin develops specific characteristics and vulnerabilities. The primary concern is the increased risk of sun damage from ultraviolet (UV) radiation. Hair normally acts as a natural sun shield, making the exposed scalp a primary target for continuous sun exposure.
Chronic UV exposure significantly increases the risk of developing actinic keratoses, which are precancerous skin lesions. Bald scalps are also at a higher risk for developing squamous cell carcinomas and basal cell carcinomas, two of the most common forms of skin cancer. Continuous weathering can also lead to a leathery texture and a noticeable shine.
Although the scalp is naturally thick skin, areas of advanced baldness can become thinner or develop a scarred appearance. Some studies suggest skin layers around shrunken follicles can thin, while others note a fibrotic thickening of the connective tissue. The exposed skin is highly sensitive to environmental factors, including temperature fluctuations. Routine use of broad-spectrum sunscreen or wearing a hat is necessary to mitigate these risks.