Skin Fascia PDF

INTRODUCTION TO ANATOMY SKIN & FASCIA Dr. Nermine Nosseir PhD, Anatomy & Embryology MSc, Leadership In Health Profession Education  Learning Objectives After the session the students should be able to: List...

INTRODUCTION TO ANATOMY SKIN & FASCIA Dr. Nermine Nosseir PhD, Anatomy & Embryology MSc, Leadership In Health Profession Education  Learning Objectives After the session the students should be able to: List Layers of the skin Describe function of the skin Describe the structure of the skin Describe the structure and function of superficial fascia. Describe the structure and functions of deep fascia. List the derivatives of the deep fascia, giving examples. List examples of serous membranes in the body  What is the Integumentary System? It is the system that protects the body from various of damage from external environment. The system includes the skin and its appendages ( including hair and nails) THE SKIN  Functions of the Skin Protections: - Ultraviolet light & Microorganisms - Abrasion, Trauma, Chemical, Mechanical insults - Prevents water loss - Cushions and insulates deeper organs Sensations: Touch & Temperature Contains sensory receptors for Pain, Pressure. Excretion: Sweat Thermoregulation : (Vasodilation & Vasoconstriction) Regulates body temperature. Metabolic : Vitamin D synthesis  Structure Of The Skin ▪ It consists of two layers: 1. The epidermis: A superficial cellular layer (stratified squamous epithelium). 2. The dermis: A deep connective tissue layer. containing hair follicle, sweat glands, sebaceous glands, blood vessels, lymphatic vessels and nerves N.B : Hypodermis : is a layer of areolar and adipose connective tissue that lies deep to the dermis. It also called the subcutaneous layer. It is not a part of the skin.  1- EPIDERMIS Layers of the Epidermis From deep to superficial: 1. Stratum basale 2. Stratum spinosum 3. Stratum granulosum 5. Stratum lucidum 6. Stratum corneum  The epidermis contains four major layers in (thin skin) or five major layers (thick skin) Stratum basale (deepest layer) or stratum germinativum, where continuous cell division occurs which produces other layers corneum Stratum spinosum, 8-10 layers of keratinocytes Stratum granulosum, which includes keratohyalin and lamellar granules Granulosum Stratum lucidum is present only in thick skin (the skin of the fingertips, palms, and soles) Basale Spinosum Stratum corneum: composed of many sublayers of flat, dead keratinocytes called corneocytes or squames that are continuously shed and replaced by cells from deeper strata; constant friction can stimulate formation of a callus. The epidermis contains four major types of cells: Keratinocytes (90% of the cells) produce keratin which is a tough fibrous protein that provides protection Melanocytes: which produce the pigment melanin that protects against damage by ultraviolet radiation Langerhans cells: involved in immune responses, arise from red bone marrow Merkel cells: which function in the sensation of touch.  Types of skin (Based on the thickness of epidermis) A. Thick Skin ▪Thick epidermis is found on the palms of the hands, the soles of the feet, and corresponding surfaces of the fingers and toes. ▪All five epidermal strata occur in thick skin. ▪None hairy (Hairless) Stratum Lucidum: Located between the stratum granulosum and stratum corneum layers, it is composed of three to five layers of dead, flattened keratinocytes. The keratinocytes of the stratum lucidum do not feature distinct boundaries and are filled with eleidin, an intermediate form of keratin. B- Thin Skin ▪ Thin epidermis covers most of the body. ▪ Has thin stratum corneum ▪ Lacks the stratum lucidum. ▪ Has only four specific layer  2- DERMIS ▪ Is a dense layer of irregular connective tissue (collagen & elastic fibers) ▪ Variable in thickness ▪ Rich in nerves, blood vessels. ▪ The deep layer of the dermis contains hair follicles, with associated smooth arrector pili muscles and sebaceous & sweat glands.  Dermis has 2 layers 1. Papillary layer: Loose connective tissue within dermal papilla, this layer is best developed in thick skin i.e. palm and sole. 2. Reticular layer: Dense connective tissue; network of thick collagen bundles and elastic fibers which form the deep part of the dermis. Facts about the skin: The hypodermis is a subcutaneous layer formed by fat. The epidermis is very thick on the palms of the hand and the sole of the foot The skin is supplied by cutaneous innervation The area of the skin innervated by a single spinal nerve is called a Dermatome  SKIN LINES A.Langer’ s lines: - They corresponds to the natural orientation of the collagen fibers. - They run vertically in the limbs and horizontally in the neck and trunk - The direction of these lines are important surgically; incisions parallel to the langers line help in healing with less scares Incisions made parallel to these lines tend to gape less and heal more readily than incisions made across cleavage lines. B. Skin Creases: - These are grooves present at sites of joints - At these sites the skin is attached firmly to the underlying deep fascia. - The creases are prominent on palms, soles wrists and digits.  Skin Appendages ▪ Nails-hard keratinized plates found on the dorsal surface of the digits. ▪ Rigid support for finger tip. ▪ Helps efficient fine movements  Hair - Hairs are filaments that arise from hair follicles (modified part of stratum corneum) - Hair follicles are tubular invaginations of epidermis. - Arrector pili smooth muscle, connects the follicle to the superficial part of the dermis Structure of the Hair  Sebaceous glands ▪ Are holocrine glands (cells of gland rupture during secretion). ▪ Secrete sebum which prevent dryness  Sweat glands ▪ Each gland is a single long tube, with highly coiled end while the body is the secretory part. ▪ It is lined by cuboidal epithelium Typical Glands: are merocrine glands (watery secretion & secrete by exocytosis).  What is fascia? Is a collection of connective tissue that lies: Under the skin where it is called superficial fascia. Deeply situated where it invests the muscles and ensheathes blood vessels and is called deep fascia.  Location of Fascia Superficial fascia Superficial Fascia (adipose tissue; hypodermis) Deep Fascia – between skin and muscles Deep fascia – found between adjacent muscles; no fat Femur Skin  Superficial Fascia It is loose connective tissue filled with fat, which varies in different parts of the body: ❖ In certain sites it is dense like in: 1. The scalp. 2. Palm of the hand. 3. Sole of the foot ❖ It is thinnest over the penis and scrotum. Superficial Fascia  Superficial Fascia Cont. Contents of Superficial Fascia 1. Fat. 2. Cutaneous arteries. 3. Cutaneous veins. 4. Cutaneous nerves. 5. Superficial lymph vessels. 6. Subcutaneous muscles. It may contain muscles as the platysma Muscles. Functions of Superficial Fascia ( For Reading) Acts as a bad conductor to heat, so it decreases the heat loss and keeps the body temperature. Gives the full rounded appearance and the smooth outline particularly in females. Facilitates the movement of the skin over the underlying structures. Provides as a good medium for the cutaneous vessels, nerves and lymphatics to form plexuses before they end in the skin.  DEEP FASCIA ▪ It is denser than superficial fascia, present mainly in the neck, upper and lower limbs. ▪ It is usually present in the form of membranes where it forms the following structures 1. Intermuscular septa. 2. Investing fascia. 3. Neurovascular sheathes. DEEP FASCIA Cont. It may be thickened to form: 1. Retinacula. (1) 1 2. Palmer and planter aponeurosis. 2  Fascia over the abdomen Superficial Fascia Superficial Deep Fatty Layer Membranous Layer No Deep Fascia Over The Abdomen WHY? Functions of deep Fascia Gives an extra origin to some muscles. The retinacula hold the long tendons in place so as to get maximum efficiency of contraction of the muscles.  Functions of deep Fascia Cont. The deep fascial septa limit the spread of Infection or blood. The strong deep fascia in the leg bounds tight osteofascial compartments in which muscles, vessels and nerves lie which help the muscle pump.  Serous Membranes These are closed sacs formed of connective tissue and that contain a thin film of fluid 1- The layer under the epidermis that contains connective tissue, hair follicles, sweat glands and nerve endings is known as A. Dermatome B. Dermis C. Hypodermis D. Serous membrane 2- Which of the following regions does not have a deep fascia? A. Upper limb B. Lower Limb C. Head D. Abdomen 3- Thin skin lakes which of the following layers? A.Stratum granulosum B.Stratum spinosum C.Stratum basale D.Stratum lucidum E.Stratum corneum