The seat of the sense of touch. In the other regions of the body these eminences are irregularly distributed, and in many parts of the skin they are so extremely small, that they have been rather admitted by analogy than from actual observation. Although in these situations the papillae cannot be distinguished in their healthy state, they may be when they are naturally enlarged by disease. <Callout type="important" title="Important">Each papilla is supposed to be provided with a delicate covering of the rete Mulpighiunum and also of the outer epidermis.</Callout> The internal surface presents numerous depressions, which were first noticed by Bichat. These are formed by the inter-crossing and weaving of the fibres which compose the true skin. - They do not entirely pierce the cutis, but end in culs de sac, which are perforated by a crowd of openings terminating on the external surface, and which may be well seen after maceration, by raising the epidermis. TheNe openings, according to Bichat, pass obliquely, and they transmit the hairs, the blood- serum, absorbents, and nerves.<Callout type="risk" title="Risk">The cutis is highly elastic, so that after it has been extended, and this may be done to a considerable degree, it readily contracts on itself to its original state.</Callout> The uses of the cutis vera are complicated and important. In the first place, by its dense and fibrous structure, it supports the more delicate textures which are placed on it; whilst by its vascular and nervous fibrils, it accomplishes most of the numerous operations which are carried on in the external cutaneous vessels. It furnishes the secreting and absorbing vessels, by which the present functions of extrinsic secretion and absorption are effected. Lastly, it is the seat of touch in all its varying degrees of perfection.<Callout type="tip" title="Tip">The skin's elasticity allows it to stretch significantly before returning to its original state, making it a crucial factor in survival scenarios where injuries may cause extensive damage.</Callout> <Callout type="warning" title="Warning">Be cautious when examining or treating wounds as the cutis can be extremely sensitive and prone to infection.</Callout>
Blood-vessels. The vessels which are connected with the true skin, are very numerous, although it must be remarked that the great part of the turgiduous and lymphatic tubes merely pass through the cutis in order to reach its external face, so that the fibrous structure itself receives but few vessels. Where the arteries are successfully injected with saffron and vermilion, the outer surface has a bright red colour, whilst the substance of the true skin is hardly white, except in those places where the vessels are transmitted. This vascular network receives its supply from arteries that are lodged in the subcutaneous cellular tissue, and which permeate the corium after having partially ramified beneath it. The minute branches form delicate penicilli, which are embedded in the velamina of the cuticle lined by the rete mucosum.<Callout type="gear" title="Gear">Leather-making processes can be used to preserve skin integrity and provide additional protection.</Callout> No vessels can be demonstrated passing to the two outer membranes of the cutaneous organ; but for the reason I have already mentioned, I believe that they are really vascular. The internal structures of Mr. Chevalier have induced him to consider this vascular structure as constituting one wide and diffused perspiratory gland, conveying to the cuticle that subtle fluid which constantly exhales from the surface of the body in every degree of gradation, from the invisible vapour of perfect health to the profuse and colliquative sweat of a languishing hectic. He contends, that the perspiratory process is not merely a secretory or separative function, but is also one attended with chemical changes; and in support of this, he mentions the well-known differences which exist in the odour and other properties of the sweat of Europeans, Negroes, and Chinese.<Callout type="important" title="Important">The cutis vera's chemical composition includes a large quantity of water, which readily evaporates after the epidermis has been removed.</Callout> The observations of Seguin and others seem to prove that there are two distinct substances in the corium; one of which consists of dense fibres forming its basis, and the other of a semi-liquid matter, interposed and contained between them. The cutis is greyish white, interspersed in some places with a reddish tinge, which seems to be produced by the injection of its blood-vessels.<Callout type="risk" title="Risk">The cutis can vary greatly in thickness depending on location, age, and constitution.</Callout> The thickness of this structure is subject to vary from two lines to the one-fourth of a line, according to its situation, also according to the sex, age, and constitution of the individual. It is remarkably thick on the heel, in the palm of the hand, and on the scalp. On the back it is usually of great thickness; in one of the measurements which I have lately made in a male, the dimension in this part was the one-fifth of an inch. It is thin on the face generally, especially on the lips and eyelids; also on the auricle of the ear, on the penis and scrotum, and in the female on the labia pudendi. In many parts of the body the dermis is so thin as to be semitransparent, allowing the colour of the parts beneath to be seen; thus the purple hue of the blood is often distinguished in the superficial veins, especially in the delicate skin of the female.<Callout type="tip" title="Tip">Understanding the varying thickness and elasticity of the cutis can help in assessing injuries and applying appropriate first aid.</Callout> It is very strong and resisting, and in this respect it exceeds most other parts of the body. This property, which is owing to its great density, remains after death: and by tanning it is even increased, the strongest ties that are employed by mechanics being formed of the leather which is produced by that process.<Callout type="important" title="Important">The cutis ts highly elastic, so that after it has been extended, and this may be done to a considerable degree, it readily contracts on itself to its original state.</Callout> The uses of the cutis vera are complicated and important. In the first place, by its dense and fibrous structure, it supports the more delicate textures which are placed on it; whilst by its vascular and nervous fibrils, it accomplishes most of the numerous operations which are carried on in the external cutaneous vessels. It furnishes the secreting and absorbing vessels, by which the present functions of extrinsic secretion and absorption are effected. Lastly, it is the seat of touch in all its varying degrees of perfection.
Key Takeaways
- The papillae on the skin's surface can be enlarged by disease and are covered by a delicate layer to protect them from external contact.
- The cutis vera has two distinct substances: dense fibres forming its base, and semi-liquid matter between them.
- Understanding the varying thickness of the dermis is crucial for assessing injuries.
Practical Tips
- When treating wounds, be cautious as the skin can be extremely sensitive and prone to infection.
- Leather-making processes can help preserve skin integrity in survival situations.
- The elasticity of the skin allows it to stretch significantly before returning to its original state, making it a crucial factor in survival scenarios.
Warnings & Risks
- Be aware that the cutis can vary greatly in thickness depending on location and constitution, which affects how injuries are assessed.
- The cutis is highly vascularized, so be careful when examining or treating wounds to avoid causing additional damage.
- The chemical composition of the skin includes a large quantity of water, which evaporates easily after the epidermis has been removed.
Modern Application
While the detailed anatomical descriptions in this chapter are primarily historical, understanding the structure and function of the skin remains crucial for modern survival preparedness. The knowledge of how the skin supports delicate textures, its vascular network, and its elasticity can help in assessing injuries, applying first aid, and preserving skin integrity during harsh conditions.
Frequently Asked Questions
Q: What are the main functions of the papillae on the skin's surface?
The papillae on the skin's surface support the sense of touch. They can be enlarged by disease and are covered by a delicate layer to protect them from external contact.
Q: How does the thickness of the dermis vary in different parts of the body?
The thickness of the dermis varies according to its location, sex, age, and constitution. It is notably thick on the heel, palm of the hand, and scalp, while it is thin on the face, lips, eyelids, ear auricle, penis, scrotum, and labia pudendi in females.
Q: What are the chemical components of the skin?
The skin's chemical composition includes a large quantity of water that readily evaporates after the epidermis has been removed. It also contains two distinct substances: dense fibres forming its base and semi-liquid matter between them.