The subcutaneous tissue (from
Latin subcutaneous 'beneath the skin'), also called the hypodermis, hypoderm (from
Greek 'beneath the skin'), subcutis, or superficial fascia,[2] is the lowermost layer of the
integumentary system in
vertebrates.[3] The types of cells found in the layer are
fibroblasts,
adipose cells, and
macrophages. The subcutaneous tissue is derived from the
mesoderm, but unlike the
dermis, it is not derived from the mesoderm's
dermatome region. It consists primarily of
loose connective tissue, and contains larger blood vessels and nerves than those found in the dermis. It is a major site of fat storage in the body.
In
arthropods, a hypodermis can refer to an epidermal layer of cells that secretes the
chitinouscuticle. The term also refers to a layer of cells lying immediately below the
epidermis of plants.
Bursae, in the space overlying joints in order to facilitate smooth passage of overlying skin
Fine, flat sheets of muscle, in certain locations, including the scalp, face, hand, nipple, and scrotum, called the
panniculus carnosus
In some animals, such as whales and hibernating mammals, the hypodermis forms an important insulating layer and/or food store.
In some plants, the hypodermis is a layer of cells immediately below the epidermis of leaves. It is often mechanically strengthened, for example, in pine leaves, forming an extra protective layer or a water storage tissue.
Subcutaneous fat
Subcutaneous fat is the layer of subcutaneous tissue that is most widely distributed.[1] It is composed of adipocytes, which are grouped together in
lobules separated by
connective tissue.[5] The number of adipocytes varies among different areas of the body, while their size varies according to the body's nutritional state.[12] It acts as padding and as an energy reserve, as well as providing some minor
thermoregulation via insulation.[10][5] Subcutaneous fat is found just beneath the skin, as opposed to
visceral fat, which is found in the
peritoneal cavity,[13] and can be measured using
body fatcalipers to give a rough estimate of total body
adiposity.[14]
Injection into the subcutaneous tissue is a
route of administration used for drugs such as
insulin: because it possesses few blood vessels, the tissue absorbs drugs slowly.[10]: 135 Subcutaneous injection is believed to be the most effective manner to administer some drugs, such as human growth hormones. Just as the subcutaneous tissue can store fat, it can also provide good storage space for drugs that need to be released gradually because there is limited blood flow. "
Skin popping" is a slang term that includes this method of administration, and is usually used in association with
recreational drugs.
^
abO'Rahilly, Ronan; Müller, Fabiola; Carpenter, Stanley; Swenson, Rand; Dartmouth Medical School.
"Chapter 4: The skin, hair and nails". Basic Human Anatomy: A Regional Study of Human Structure. Retrieved 9 June 2013.
^Fischer, Josef E.; Bland, Kirby I.; Callery, Mark P. (18 December 2006). Mastery of Surgery. Lippincott Williams & Wilkins. p.
482.
ISBN078177165X.
^Krstic, Radivoj V. (18 March 2004). Human Microscopic Anatomy: An Atlas for Students of Medicine and Biology. Springer. p. 466.
ISBN9783540536666.
^
abcKenneth, Saladin (2007). Human Anatomy. Rex Bookstore, Inc. pp. 135, 478, 602.
ISBN978-0071259712.
^Goldsmith, Lowell A.; Katz, Stephen I.; Gilchrest, Barbara A.; Paller, Amy S.; Leffell, David J.; Wolff, Klaus (10 April 2012). Fitzpatrick's Dermatology in General Medicine (8 ed.). McGraw-Hill. p. 64.
ISBN978-0071669047.
^"Subcutaneous Tissue". Medical Subject Headings (MeSH). National Library of Medicine. Retrieved 5 June 2013.