Photos & Illustrations

Scientific Illustrations | Jun 14, 2007

The human hand

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The properties and functions of the human hand make it a unique high-performance tool which is used for all kinds of work around the house, the garden, or on the job. It is a complex organ used for grasping and gripping and may be vulnerable when exposed to negative influences.

Skin on the hands differs significantly from that of other areas of the body. The palms of the hand have a strong subcutis fatty tissue, which is rich in lipids and connective tissue, while the skin of the back of the hands is rather thin between the fingers and the skin folds because of little fatty tissue in the subcutis. In this area, the skin may be impaired by exogenous influences and a defattening process may occur. The hydrolipidic film structure (acid mantle). It is less than 1 µm thick and is formed by the secretion of the sebaceous glands, sweat glands, and lipids of the horny layer (intercellular cement). Depending on the amount of sweat, water-in-oil (W/O) or oil-in-water (O/W) emulsion types are formed. The hydrolipidic layer also functions as a buffer against alkaline and acidic substances and is the basis for the acid reaction of the skin’s surface at a pH between 4.2 and 5.6.

If the hydrolipidic film structure is disturbed, the skin on the hands may dry out quickly and skin barrier disturbances, sensibilization reactions and contact eczema may result as a consequence. The various types of skin diseases in the workplace therefore occur on the hand and underarms.

The exterior layer of the skin (horny layer, stratum corneum) has a distinctive barrier function and is naturally protected from mechanical work such as pressure and pushes, thermal influences such as heat or cold, UV irradiation, chemical or bacterial influences. Thus, the epidermis, the outermost skin layer, forms a wrap over the skin’s surface.

Our schematic representation shows the structure of the stratum corneum by means of the "brick-and-mortar" model. The bricks are symbolizing the horny skin cells (corneocytes) which consist of hydrated keratin and the space between these dead cells is filled up by epidermal lipids like mortar.

In the magnified section, a further enlargement of the horny layer is displayed. In healthy skin (left) this structure is intact, while the natural condition of the skin is in disbalance in impaired skin (right). Regular handwashing, exposing the hands to soap, solvents, acid, alkaline substances, heat and cold or mechanical stimuli are factors which may have an adverse effect on the skin’s condition.

These various exogenous factors which may have negative effects on the intact skin structures are exemplified in our illustration by pictographs. They represent mechanical use, exposure to wind and all types of weather, bathing, showering, swimming, chemicals and bacteria.

When hands are strongly exposed to various exogenous factors, skin cleansing with specific products should play a major role. To avoid eczema and allergic reactions, the use of hand protection creams is recommendable which are specifically designed for use on the skin of the hands.

Also see:

  • New publication on skin protection, book review by Wolfgang Pittermann, Alles über Hautschutz, Hautreinigung, Hautpflege, Eds.: W. Dicke, I. Funk-Stendel, B. Marschner, F. Zuther in: Skin Care Forum 41.
  • Joachim Kresken, Skin Protection in the Workplace; Skin Care Forum 21.