Your subcutaneous tissue is the deepest layer of your skin. The prefix “sub” comes from the Latin word meaning under, and the word cutaneous derives from the Latin word “cutis,” which means skin.

Other names for subcutaneous tissue include superficial fascia, hypodermis, subcutis, and tela subcutanea. No matter what you call it, your subcutaneous tissue plays an essential role in helping your body regulate its temperature and protecting your organs from shock.

Let’s examine the importance of subcutaneous tissue and a number of medical conditions that affect this tissue.

Your skin is made up of three layers: the epidermis, dermis, and subcutaneous tissue.

  • Epidermis. The outermost layer of your skin is made up of overlapping cells that provide a waterproof barrier and protection from the outside world.
  • Dermis. The middle layer of your skin contains sweat glands, lymphatic vessels, blood vessels, connective tissue, and hair follicles.
  • Subcutaneous tissue. The deepest layer of skin is made of connective tissue and fat.

Subcutaneous tissue is well-vascularized, meaning that it’s filled with blood vessels. It’s also the layer where your body stores visible body fat.

In some parts of your body, such as your eyelids, the subcutaneous layer doesn’t contain fat and can be thinner than 1 millimeter (0.04 inches). In other areas like your buttocks and abdomen, your subcutaneous tissue may be more than an inch thick, depending on your overall body fat percentage.

Connected to the bottom of your subcutaneous fascia is muscle covered in a dense layer of connective tissue called your deep fascia.

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Subcutaneous Tissue (Hypodermis)

In many parts of your body, the fat in your subcutaneous tissue plays a role similar to insulation in your house. This fat helps protect the deep structures in your body like your muscles and organs from changes in temperature and absorbs shock to underlying structures.

The subcutaneous layer plays a number of other roles, such as:

  • gives your body a smooth and contoured appearance
  • serves as an attachment site for your underlying muscles and fascia
  • stores fat cells that act as energy reserves and produce hormones like leptin
  • contains deep pressure sensors
  • contains blood vessels that play a role in thermoregulation

Subcutaneous fat refers to body fat stored in your subcutaneous tissue. This fat is stored in adipocytes (fat cells) that are separated by connective tissue. Some layers of subcutaneous tissue like the eyelids and penis don’t contain this fatty layer.

Subcutaneous fat is one of three types of fat in your body. You also have essential fat in your bones, nerves, and organs, as well as visceral fat in your abdominal cavity.

Many types of medications can be delivered via subcutaneous injection. Medications injected into your subcutaneous layer are absorbed more slowly than when injected directly into a blood vessel.

Subcutaneous injection is widely used for drugs that need to be continuously absorbed or given in low doses. These injections are a highly effective option for delivering vaccines, insulin, or growth hormones.

Other types of drugs that may be administered in this way include:

Common sites for a subcutaneous injection include:

  • outer surface of your upper arm
  • top of your thigh
  • buttocks
  • abdomen

A number of medical conditions occur in your subcutaneous fascia. These include:


Burns that reach your subcutaneous layer are known as third-degree burns. These burns often leave a charred and white wound. Third-degree burns are a medical emergency and need prompt medical attention.


Panniculitis is a group of conditions that causes inflammation of your subcutaneous fat. Panniculitis causes painful bumps of varying sizes under your skin. There are numerous potential causes including infections, inflammatory diseases, and some types of connective tissue disorders like lupus.


An abscess is a bump filled with pus and other fluid beneath your skin. Subcutaneous abscesses are often caused by a bacterial infection after a traumatic injury. A medical professional usually treats an abscess by making an incision and draining it.


Both benign and cancerous tumors can form in the fat, connective tissue, or blood vessels of subcutaneous tissue. According to the American Cancer Society, there are more than 50 types of cancerous tumors that can form in soft tissue.

Age-related skin conditions

Facial aging is partially caused by loss of the subcutaneous fat content in your skin. Loss of subcutaneous fat over time can lead to sagging skin, especially around your chin and neck.

Pressure ulcer

A pressure ulcer, or bedsore, is a wound caused by being stationary in one position for too long. Late-stage pressure ulcers can spread to the subcutaneous layer and even the muscle and connective tissue below.

Subcutaneous tissue is the deepest layer of your skin. It’s made up mostly of fat cells and connective tissue. The majority of your body fat is stored here.

The subcutaneous layer acts as a layer of insulation to protect your internal organs and muscles from shock and changes in temperature. It also provides your body with an energy reserve.