1. What is the structure of the skin and subcutaneous tissues? The skin covers the surface of the whole body and has many important functions such as protecting the tissues in the body, sensing stimuli such as temperature, pain, touch and pressure, regulating body temperature and excreting waste. The skin consists of the epidermis, dermis and subcutaneous tissues. In addition, the skin is also derived from many accessory structures. The epidermis is the most superficial layer of the skin. It is a keratinized, compound flat epithelium. The cells of the deeper layer have the ability to divide and are the basis for the cellular origin of the superficial layer, hence the name anagen layer, which divides and pushes towards the surface. The cells in the superficial layer become flattened by keratinization and die, and are called the keratinized layer. It is continuously shed and regenerated and has an anti-friction effect. The deeper cells of the epidermis contain melanin granules. When there are more melanin particles, the skin becomes darker and vice versa. Melanin absorbs UV rays to protect the internal tissues from UV damage. The epidermis contains 7-dehydrocholesterol (the predecessor of vitamin D), which can form vitamin D after ultraviolet radiation. epidermis has an absorption effect, certain fat-soluble substances and ethanol answer easily through the epidermis and more absorption, so some topical drugs are often made into ointment or tincture to be absorbed through the epidermis to play a therapeutic role. The dermis is located on the deep surface of the epidermis and is composed of dense connective tissue. Rich in collagen fibers and elastic fibers, so the skin has a certain elasticity and toughness, can withstand a certain amount of friction and extrusion. The dermis is rich in blood vessels, lymphatic vessels and nerves, as well as sebaceous glands, sweat glands and hair roots. Subcutaneous tissue (superficial fascia) is located in the deep surface of the dermis, composed of loose connective tissue and fat, with insulation and buffering the role of mechanical pressure. The thickness of the subcutaneous tissue varies with age, gender, health and body part. As the name implies, a bedsore is an ulcer that occurs on the part of the body that is in contact with the mattress during prolonged bed rest. In Chinese medicine, it is also known as a sore. Decubitus ulcers are now commonly referred to as necrosis and ulceration of the skin in any part of the body, especially in the bone elevation, which has suffered from excessive pressure over a long period of time. For example, ulcers on the soles of the feet of paraplegics are also called bedsores. Decubitus ulcers can cause damage from the epidermis to the subcutaneous tissues, muscles, and even bones and joints, and can cause sepsis secondary to infection in severe cases. 3. Why decubitus ulcers are also called pressure sores and pressure ulcers Some doctors write the diagnosis of decubitus ulcers as pressure ulcers, and some refer to decubitus ulcers as pressure sores, because pressure is the main reason for the occurrence of decubitus ulcers. Pressure ulcers or pressure ulcers are based on the cause of their development, while decubitus ulcers are a figurative naming, a traditional customary term. However, if an ulcer occurs at the sciatic tuberosity due to sedentary reasons or a plantar ulcer due to standing or walking, it is obviously not appropriate to call it a decubitus ulcer, so it is more scientific and more accurate to call it a pressure ulcer. In this book, the traditional customary terminology is used. It is still collectively referred to as decubitus ulcers. Another important reason for decubitus ulcers is the presence of local sensory impairment. The protective function of the skin is dependent on the sensory nerves. In patients with spinal bladder injury, the central nerve is damaged and nerve conduction is interrupted below the plane of injury (or lesion), so sensation disappears completely, and protection is lost. At the same time, because the nerve injury after the vegetative nerve dysfunction, affecting the nerve to the skin nutrient function. Make the patient prone to skin damage, necrosis and ulcers. Any decubitus ulcer that occurs as a result of spinal cord injury and is accompanied by a sensory disorder is also called a trophic ulcer. The bed sores that occur in patients who are bedridden for a long time (such as elderly fracture patients) without spinal cord injury and sensory impairment cannot be called trophic ulcers. 5. What is the danger and severity of bedsores? Bed sores are characterized by high incidence, rapid development, difficulty in healing, and easy recurrence after healing. According to a sample of paraplegic patients from the Huangpu District Disabled Persons’ Federation, 80% of the patients had bed sores. Forty percent of the patients had recurrent bedsores, and 10% of the patients had not been cured despite active treatment. Among them, 20% of patients have been sick for more than 10 years, and the longest one is 25 years. In some cases, the bedsores were only the size of a nickel when they first occurred. Due to improper treatment, the bedsores develop into serious bedsores with large bowls in just a few months. Untreated decubitus ulcers can be complicated by osteomyelitis, sepsis and hypoproteinemia. These complications not only make treatment more difficult, but also lead to death in some cases. Decubitus ulcers are still one of the main causes of death in paraplegic patients. This shows that. Although a bedsore is a small ulcer, it can be extremely harmful if not treated properly.