Dermis
Corium · true skin
The dermis is the thick, tough layer directly beneath the epidermis, the skin’s outer covering. It makes up most of the skin’s thickness, provides support to keep the skin firm and elastic, and houses blood vessels, nerves, sweat glands, and hair roots. The touch and temperature sensations we feel through our skin, as well as the appearance of wrinkles and stretch marks, are also closely related to the condition of the dermis.
Where is it, and what does it do?
From top to bottom, the skin consists of three layers: the epidermis, dermis, and subcutaneous tissue. The outermost epidermis is a thin protective barrier, while the dermis beneath it forms the main body of the skin. The Korean name for the dermis means “true skin,” and its English name is dermis. Its thickness varies by location: it is less than 1 millimeter in thin areas such as the eyelids, but reaches several millimeters on the back and soles of the feet.
The dermis is further divided into two layers.
- Upper layer (papillary layer) — This is a thin, soft layer that borders the epidermis. Finger-shaped projections extend toward the epidermis, firmly joining the two layers. It contains many small blood vessels and touch receptors. The shape of these projections also gives rise to fingerprints.
- Lower layer (reticular layer) — This thick, densely packed layer makes up most of the dermis. Thick bundles of Collagen and Elastic fibers are woven into a mesh, giving it the ability to resist pulling and return to its original shape when released.
The workers that build and maintain this mesh are Fibroblasts. Fibroblasts produce collagen, elastic fibers, and the gel-like ground substance that fills the spaces between them.
The dermis houses the structures responsible for many of the skin’s functions. These include blood vessels and sweat glands that regulate body temperature, hair roots that produce hair, sebaceous glands that release oil, and sensory nerve endings that detect pressure, vibration, stretching, and pain. The epidermis has no blood vessels, so it also relies on nutrients supplied from the dermis.
How is it viewed in Integrative Manual Therapy?
Books on Integrative Manual Therapy (IMT) introduce the dermis as part of Connective tissue. They also sometimes describe the dense connective tissue in deeper layers, where tissues such as tendons intertwine at their attachment sites on bone, as the same type of tissue as the dermis. This approach views connective tissue as a continuous whole, extending from just beneath the skin to the membrane surrounding bone. Gently pulling or pushing the skin is therefore considered a way to reach the underlying Fascia. Assessing how freely the skin and fascia glide against each other can also be a starting point for manual therapy.
Connective tissue massage is a representative method of approaching the fascia through the skin. It uses long, dragging strokes of the fingers over the skin to elicit a response in the underlying tissues.
How it shows up in everyday life
- Elasticity and wrinkles — With aging or substantial sun exposure, collagen and elastic fibers in the dermis decrease and become disorganized. The skin then becomes thinner and sags, and wrinkles deepen. See Skin elasticity and collagen for more details.
- Stretch marks — When body weight increases or decreases suddenly, the fibers in the dermis stretch excessively and separate. Stretch marks are the streaks left in the dermis while the epidermis remains intact.
- Scars — When a wound extends deep into the dermis, collagen is laid down in a different pattern than usual as it heals, leaving a scar. Scrapes involving only the epidermis heal without scarring.
- Touch — The ability to detect very light contact at the fingertips or lips comes from the densely packed sensory nerve endings in the dermis.
Ways to care for it
- Protect against ultraviolet rays — Sunlight is the main reason collagen in the dermis decreases. Use sunscreen and wear a hat when going outdoors.
- Adequate hydration and nutrition — Protein and vitamin C are needed to make collagen. A balanced diet and sufficient sleep provide the foundation for your skin.
- Avoid smoking and exercise regularly — Smoking adversely affects blood circulation and collagen in the dermis. When exercise improves circulation, the skin also receives nutrients more effectively.
- Gentle stroking — Slowly stroking the skin with your palms while applying lotion after a shower helps maintain gliding between the skin and the tissues beneath it. Take care not to rub too hard.
If your skin color suddenly changes or a mole becomes noticeably larger, treat it as an unusual change and ask a professional to assess it.