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 cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

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 Taxonomy (biology), 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 ...

, 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 Organ (biology), 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 ...

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 str ...

. 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 ...

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

medicine Medicine is the science and Praxis (process), practice of caring for a patient, managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, and Health promotion ...

, because some of them are susceptible to

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

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 d ...

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 vi ...

, 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 mu ...

in the dermis 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'', 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 head ...

: * Nasolabial fold *

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 "sligh ...

* 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. ...

* Triceps skinfold *

Webbed neck A webbed neck, or pterygium colli, is a congenital skin fold that runs along the sides of the neck down to the shoulders. There are many variants. Signs and symptoms On babies, webbed neck may look like loose folds of skin on the neck. As the c ...

References

Skin anatomy Human anatomy {{anatomy-stub

Skin creases, skin folds and lines

Human skin folds

See also

References