The Subcutaneous Layer of Skin
The hypodermis is the bottomlayerof skin.
Together, these layers provide abarrier against fluids, infection, and trauma.
This article discusses the hypodermis layer of the skin.
Illustration by Zoe Hansen for Verywell Health
It explains the anatomy and function of the subcutaneous tissue.
It also covers potential health conditions and the effect of aging on the hypodermis.
Most of the body’s fat is stored in this layer.
It provides insulation, protection, temperature regulation, and connection between the bones and muscles.
The thickness of the hypodermis varies in different regions of the body and can vary considerably between different people.
The hypodermis layer also provides shaping and contouring.
For those assigned male at birth, the hypodermis is thickest in the abdomen and shoulders.
These include:
Connective tissues in the hypodermis also support structures such as nerves and blood vessels.
Associated Conditions
The following are medical disorders and procedures related to this unique layer of the skin.
Hypothermia and Overheating
The hypodermis is essential for body temperature regulation.
It traps heat and protects you from the cold.
With age, the hypodermis thins.
This is one of the reasons that older people are more prone tohypothermia.
Obesity
Body fat in the hypodermis layer is called subcutaneous adipose tissue (SAT).
This is different thanvisceraladipose tissue (VAT) that lines internal organs.
Excess fat in either area leads to obesity.
Bedsores are most common in people who are bedbound or consistently use a wheelchair.
Bedsores are difficult to treat and can lead to complications if nottreated aggressively.
Panniculitis
Panniculitisrefers to inflammation of subcutaneous fat.
It is an uncommon condition that causes hardened nodules or plaques that you could feel and sometimes see.
Panniculitis commonly affects the shins and calves before spreading to the thighs and upper body.
It usually clears within six weeks, leaving no scars.
Swelling, redness, bruising, and joint pain are common.
It also increases the risk of severe bacterial infection and permanent nerve damage.
Third-degree burns can appear dry and leathery with a combination of red, white, or blackened tissues.
You may also see the yellowish adipose tissues peeking through.
Because many nerve endings will have been destroyed, third-degree burns aren’t usually painful to the touch.
One exception issoft tissue sarcomaswhich originate in the body’s soft tissues.
These include tissues like muscle, fat, blood vessels, nerves, tendons, and cartilage.
The bones and muscles of the face also lose volume.
Medications given by subcutaneous injection are absorbed more slowly than drugs given by intravenous injection.
This makes them ideal for many drugs, especially those that are self-administered.
Summary
The hypodermis is the innermost layer of the skin.
This layer can be used for injections with some types of medication.
The hypodermis provides shaping and contour.
The thickness varies per person, with excess fat in this layer leading to obesity.
This layer of the skin thins with age, increasing the risk of hypothermia or heat exhaustion.
There are three layers of the skin, including the epidermis, dermis, and hypodermis.
The dermis is below the epidermal layer of skin that you see and above the hypodermis.
chapter 3: The skin, hair, and nails.New York: Springer Pub.
Mittal B.Subcutaneous adipose tissue & visceral adipose tissue.Indian J Med Res.
2019;149(5):571-573. doi:10.4103/ijmr.IJMR_1910_18
MedlinePlus.How to care for pressure sores.
Wick MR.Panniculitis: a summary.Semin Diagn Pathol.
Stanford Children’s Health.Anatomy of the skin.
National Human Genome Research Institute.Fibroblast.
