Hypodermis (Subcutaneous Tissue)

What is the hypodermis?

Your skin has three main layers:

• The hypodermis (subcutaneous tissue) is the innermost layer of skin in your body.
• The dermis is the middle layer.
• The epidermis is the outermost layer.

What is the hypodermis’s function?

The hypodermis has many functions, including:

• Connection: The hypodermis connects your dermis layer to your muscles and bones.
• Insulation: The hypodermis insulates your body to protect you from the cold and produces sweat to regulate your body temperature, protecting you from the heat.
• Protecting your body: The hypodermis allows your skin to move smoothly over the tissues and muscles underneath it. Without the hypodermis, your skin would rub against those tissues and muscles. It also acts as a shock absorber to protect your organs, muscles and bones from harm.
• Storing energy: The hypodermis produces fat cells (adipocytes), which store energy.

What is in the hypodermis layer?

The hypodermis layer includes:

• Adipose tissue: Adipose tissue is a fatty tissue that consists mostly of adipocytes.
• Blood vessels: Blood vessels include arteries, capillaries and veins. They circulate blood throughout your body, help deliver oxygen to vital organs and remove waste products.
• Bursa: A bursa is a small, slippery, fluid-filled sac in your body. Bursae (plural form of bursa) act as a cushion and lubricant. They protect bones from rubbing or sliding against tendons, muscles or skin.
• Connective tissue: The proteins collagen and elastin make up the connective tissues in your body. They connect all of the structures in your body and provides a support structure for other components of the hypodermis.
• Fibroblasts: Fibroblasts are a type of cell in your connective tissue. They release collagen, which helps make up your connective tissue.
• Hair follicles: Hair follicles are areas of the epidermis and dermis that fold together to create a tube-like structure. These structures extend into the hypodermis, which is where the hair starts growing.
• Lymphatic vessels: Lymphatic vessels are the network of capillaries (microvessels) and a large network of tubes located throughout your body that transport waste products (lymph) away from tissues.
• Macrophages: Macrophages are a type of white blood cell. They attack and destroy microbes.
• Nerves: Nerves send electrical signals to and from other cells, glands and muscles all over your body. They receive information from the world around you and then interpret the information and control your response.
• Sweat glands: Sweat glands keep your body temperature around 98.6 degrees Fahrenheit (37 degrees Celsius) by releasing sweat when you’re in a warm environment or working out.

What is the hypodermis responsible for?

Together with your other layers of skin, the hypodermis protects your skeletal system, organs, muscles and tissues from harm.

Hypodermis thickness differs across your body. Fatty tissue amasses in different parts of your body according to hormones and genetics.

If you have a higher amount of testosterone in your body, your hypodermis is thickest in your abdomen, arms, lower back and shoulders.

If you have a higher amount of estrogen in your body, your hypodermis is thickest in your butt, hips and thighs.

Where is the hypodermis located?

The hypodermis is the bottom layer of your skin, located below the epidermis (top layer) and dermis (middle layer) in your skin.

What color is the hypodermis?

The hypodermis is yellowish. Depending on how much of the pigment called carotene is in your hypodermis, it can be dark yellow or light yellow.

How big is the hypodermis?

The hypodermis varies in thickness across your body. It’s thinnest over your eyelids and external genitals, where it may be less than 1 millimeter thick. It’s thickest in your abdomen and butt, where it may be over 3 centimeters thick.

What is the hypodermis made of?

Connective tissue and adipose tissue mostly make up the hypodermis.

What are the common conditions and disorders that affect your hypodermis?

Some conditions and disorders that affect the hypodermis include:

• Bedsores.
• Hypothermia.
• Panniculitis.
• Sarcoidosis.
• Third-degree burns.
• Tumors.

Additionally, as you age, the hypodermis starts to thin. As a result, less connective tissue joins your dermis to your muscles, tissue and bones, and your skin starts to sag.

What are common signs or symptoms of hypodermis conditions?

Some common signs or symptoms of conditions that can affect your hypodermis include:

• Dark spots or growths that change shape or color.
• Decreased blood flow.
• Deep, open sores wherein you can see the hypodermis.
• Sweating less.
• White or charred (black) skin that is painless.

What are common tests to check the health of your hypodermis?

Your healthcare provider will conduct a physical exam to check for any possible symptoms or conditions. They may also perform the following tests:

• Blood tests. Blood tests can diagnose allergens or diseases.
• Biopsy: A healthcare provider will remove a sample of skin from your body and examine it under a microscope to look for diseases, infections or cancer.

If you have melanoma, you may need further imaging tests to determine if it has spread.

What are common treatments for conditions of your hypodermis?

Some common treatments for conditions that affect your hypodermis include:

• Debridement. Debridement is a process that removes dead tissue from a wound. Ultrasound, lasers, pressurized fluid or surgery can remove the dead tissue.
• Dermal fillers. Dermal fillers are injections that add volume to wrinkles or sagging skin. Common dermal fillers include hyaluronic acid (Juvederm®), polylactic acid (Sculptra™) or polyalkylimide (Aquamid™).
• Skin grafts. Skin grafts treat damaged or missing skin that can’t heal on its own. Skin grafts help people with deep skin damage or loss from burns, infections and ulcers.
• Skin substitutes. Skin substitutes include cells or tissue taken from another person (allograft), cells or tissue taken from an animal (xenograft) or skin made from nonbiological molecules and polymers (synthetic skin). Skin substitutes help people with deep skin wounds or conditions, including burns and infections.
• Warming your body. If you have hypothermia, you must move to a warm location, remove wet clothing and put on dry clothing. In severe cases, your healthcare provider may insert an IV into your vein to pump warm fluids into your body. They also may give you warm oxygen through a mask or breathing tube.

Are there ways to keep your hypodermis healthy?

The following lifestyle tips help keep your hypodermis healthy and safe:

• Properly treat your wounds. Wash small open wounds with clean running water and soap to prevent infections. Then, use a cotton swab to apply a small amount of petroleum jelly (Vaseline™) or skincare ointment (Aquaphor™) over the wound, and cover it with an adhesive bandage to prevent dirt or bacteria from entering the area.
• Avoid sun damage. Long exposure to the sun damages your skin. Use sunscreen with an SPF of at least 30 and wear protective clothing. Reapplying sunscreen is also important to reduce sun damage.
• Take precautions to avoid burns. Keep the water heater in your home below 120 degrees Fahrenheit, use the back burners on your stove as much as possible when cooking, don’t leave a stove unattended and lock up chemicals, lighters and matches.
• Keep your body warm. To avoid developing hypothermia, wear warm clothes, keep your home at a temperature above 68 degrees, move around when you feel cold and regularly warm up inside whenever you spend time outside during cold weather.

A note from Cleveland Clinic

The hypodermis is the bottom layer of skin in your body. It has many important functions, including storing energy, connecting the dermis layer of your skin to your muscles and bones, insulating your body and protecting your body from harm. As you age, your hypodermis decreases in size, and your skin starts to sag. Dermal fillers help restore volume to your skin as your hypodermis decreases.