Skin and Fascia Anatomy: PDF Guide

Okay, here's the transcription, summarization and formatting of the text from the images, presented in Markdown: ## Skin and Fascia * The skin is the largest organ of the body. * Skin constitutes about 16% of total body weight in an average adult. ### Function of the skin: 1. Protects us fr...

Okay, here's the transcription, summarization and formatting of the text from the images, presented in Markdown: ## Skin and Fascia * The skin is the largest organ of the body. * Skin constitutes about 16% of total body weight in an average adult. ### Function of the skin: 1. Protects us from microbes, trauma, and UV light. 2. Regulates body temperature *(sweat gland - capillaries network)*. 3. Sensation of touch, heat, and cold. 4. Excretory system: (Urea - salt - sweat) - Integumentary system)) 5. production of vitamin D: *(using U.V radiation to synthesize vitamin D >> Calcium)*. * The skin is the outer covering formed of three layers: * Superficial epithelial layer *(epidermis)*.  * Deep connective tissue layer *(dermis)*.  * Subcutaneous tissue *(hypodermis)*. * The color of the skin is determined by the amount of melanin secreted by melanocytes in the epidermis. * The thickness of the skin varies in different parts of the body: it is thick in the palm and sole, while thin in lips or joints. **Image Description**: The image shows a cross-section of the skin with labels pointing to the different structures of the skin * Epidermis * Dermis * Subcutis/Hypodermis * Hair shaft * Sweet pore * Arrector pili muscle * Hair root * Hair follicle * Hair follicle receptor (root hair plexus) * Artery * Adipose (fat) tissue * Vein * Sabaceous (oil) gland * Eccrine sweat gland ### **Epidermis:** * Outmost layer * Stratified squamous epithelium with no blood vessels *(avascular)*. * Cells are closely packed together to act as a barrier * Thick over the heel and thin over eyelids. ### **Dermis:** * Connective tissue containing blood vessels, lymph vessels, hair follicles, sweat glands and sebaceous glands. ### **Hypodermis:** * Called subcutaneous fascia. * Has some skin appendages e.g.: hair follicles, blood vessels, and nerves. * Is a fatty layer that lies just deep to the skin. ### **Langer's lines (cleavage lines):** * Longitudinal in limbs * Transverse in trunk * Have surgical importance as incisions made parallel to them heal better and produce less scaring. It corresponds to the orientation of collagen fibers in the dermis. ### **Skin creases:** * Small grooves present at the site of joints where skin is strongly attached to the deep fascia. * Sites include flexor surfaces of the palm, sole, and digits to facilitate movement. **Image Description**: The image shows diagrams of a human torso and arm demonstrating Langer's lines, along with a close-up of the palm of a hand showing skin creases. ### Fascia The tissue that lies under the skin and consists of 2 layers: ### Superficial fascia: Loose areolar connective tissue with collagen and elastic fibers and adipose tissue *(fats)*. * Connect skin dermis to the underlying deep fascia and facilitates its movement over them. * The superficial fascia is firmly attached to the skin in the scalp, back of the neck, palm of hands and sole of the foot. * The superficial fascia is loosely attached to the skin in the dorsum of hands and dorsum of the foot. * The superficial fascia is devoid of adipose tissue in eyelids, auricle of ear, penis & scrotum in male and clitoris in the female. ### Function of superficial fascia: * Facilitates movement of the skin. * Keeps body temperature constant by being a bad conductor of heat. * Gives the body its smooth outline as it fills up hollows and irregularities of the body. * Contains blood vessels, nerves, lymph glands and sometimes subcutaneous muscles as in face and scrotum ### Deep fascia: *(Absent in the face - scalp - anterior abdominal wall)*. Is more dense than superficial fascia; usually present as membranes that invest muscles and other deep structures. ### Function: * Assists muscle action by the pressure it exerts on their surfaces. * Forms intermuscular septa which divides limbs into compartments. * Thickened in palm and sole to form aponeurosis to provide protection to the underlying deep structures. * Thickened over the flexor tendons of hand an sole form fibrous flexor sheath to stabilize tendons. * It helps venous return against gravity in the limbs by squeezing blood in the veins towards the heart. **Image Description**: Illustration section of skin layers highlighting superficial fascia (connective tissues) and deep fascia.