Skin folds or skinfolds are areas of

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

that are naturally folded. Many skin folds are distinct, heritable anatomical features, and may be used for identification of animal

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

, while others are non-specific and may be produced either by individual development of an organism or by arbitrary application of force to skin, either by the actions of the

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

s of the body or by external force, e.g.,

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

. Anatomical folds can also be found in other structures and tissues besides the skin, such as the ileocecal fold beneath the terminal ileum of the cecum. Skin folds are of interest for

cosmetology Cosmetology (from Greek , ''kosmētikos'', "beautifying"; and , '' -logia'') is the study and application of beauty treatment. Branches of specialty include hairstyling, skin care, cosmetics, manicures/ pedicures, non-permanent hair removal such ...

, as some kinds may be considered aesthetically undesirable, and for

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...

, because some of them are susceptible to

inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

and

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...

Skin creases, skin folds and lines

The skin creases of the human body are features of great anatomical, morphological, and surgical interest and important for the maintenance of the contour of each anatomic area. In the literature, when referring to a skin crease, there is variation of terms used other than "crease", such as "fold" and " sulcus", but these terms do not accurately reflect their histology structure nor their function. In the review of literature, a record of the creases of the human body for each anatomic area, including the synonyms that are used for each crease in the literature, has been attempted. The skin crease as a fixed and permanent line, according to their

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures v ...

, is related to connective tissue attachments with the underlying structures or extensions of the underlying

muscle fibers A muscle cell is also known as a myocyte when referring to either a cardiac muscle cell (cardiomyocyte), or a smooth muscle cell as these are both small cells. A skeletal muscle cell is long and threadlike with many nuclei and is called a mus ...

in the

dermis The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided ...

of the crease site. The skin fold is characterized by skin redundancy that is responsible partly, often in combination with connective tissue attachments, for the skin crease. It is essential to use appropriate terms that accurately reflect the anatomic structure and histology when referring to the skin lines.

Human skin folds

$Skin folds close to a hip fracture (with arrows)$ The following distinct skin fold types are among the roughly 100''

Dorland's Illustrated Medical Dictionary ''Dorland's'' is the brand name of a family of medical reference works (including dictionaries, spellers and word books, and spell-check software) in various media spanning printed books, CD-ROMs, and online content. The flagship products are ''Do ...

'', 27th edition, pp. 645–6 identified in

human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a hea ...

: *

Nasolabial fold The nasolabial folds, commonly known as "smile lines" or "laugh lines", are facial features. They are the two skin folds that run from each side of the nose to the corners of the mouth. They are defined by facial structures that support the bucca ...

Epicanthal fold An epicanthic fold or epicanthus is a skin fold of the upper eyelid that covers the inner corner (medial canthus) of the eye. However, variation occurs in the nature of this feature and the possession of "partial epicanthic folds" or "slight e ...

* Interdigital folds (Plica Interdigitalis) *

Inframammary fold In human anatomy, the inframammary fold (IMF), inframammary crease or inframammary line is the natural lower boundary of the breast, the place where the breast and the chest meet. The choice of the term depends on the prominence of the feature. It ...

* Triceps skinfold * Webbed neck

References

Skin anatomy Human anatomy {{anatomy-stub

Skin creases, skin folds and lines

Human skin folds

See also

References