Skin & Fascia Lecture 2 Anatomy Unit PDF

Skin & Fascia Lecture 2 Anatomy unit  Objectives Describe layers of skin. Enlist the functions of skin. Recognize the importance of skin creases and dermatomes and relate this to applied anatomy (surgical incisions) Define appendages of skin. Define fascia. Different...

Skin & Fascia Lecture 2 Anatomy unit  Objectives Describe layers of skin. Enlist the functions of skin. Recognize the importance of skin creases and dermatomes and relate this to applied anatomy (surgical incisions) Define appendages of skin. Define fascia. Differentiate between superficial and deep fascia. Emphasize the clinical application. Skin 1. Is considered the largest organ of the body. 2. Forms the external surface of the body. Consists of 2 layers: A) Superficial epithelial layer called epidermis and, B) Deeper connective tissue layer called dermis. Structure of the skin  Epidermis.  It is composed of keratinizing stratified squamous epithelium.  It is devoid of blood vessels and gets its nutrition through diffusion.  The epidermis Generally is thin except……?  Dermis It Consists of connective tissue. Contain 1. Blood vessels, Lymph vessels, 2. Sensory nerve endings, 3. Autonomic nerves. 4. Hair follicles. 5. Smooth muscle fibers attached to the hair follicles. 6. Glands (sweat and sebaceous) DERMIS-INTRADERMAL INJECTIONS EXTRA READING INJECTION https://next.amboss.com/us/search?q =different+types+of+injections&v=o verview&m=6IajdN  Skin creases Folded skin over the joints. Skin is thin and is adherent to underlying structures.  Lines of cleavage (Langer's lines)  The collagen fibers, arranged in parallel rows (Lines of cleavage-langer’s lines).  The direction of the rows of collagen fibers in the dermis,  The direction of Langer's lines: 1. Longitudinally in the limbs. 2. Circumferentially in the neck and trunk.  Lines of cleavage These lines are important to determine the direction for an incision (cut) during a surgery to avoid obvious scars.  Incisions made across Langer's lines: Retraction & gaping of wounds & prominent scar  Incisions made parallel to Langer's lines: Decrease tendency of wound to retract & less scars formation  Pigmentation of the skin The color of the skin is determined by the presence of melanin pigments. The melanin pigments protects the deep germinative layer from damage by ultraviolet rays.  DERMATOME The surface of the skin is divided into specific areas called dermatomes.  A dermatome is an area of skin in which sensory nerves derive from a single spinal nerve root. Dermatomes are useful to localize neurologic levels.  Also, infections like herpes zoster (shingles), can reveal their origin by showing up as a painful dermatomal area.  Skin burns Superficial Deep Heals rapidly from the Heals slowly from the edges. edges, Heals quickly. Usually needs skin grafting. Doesn’t need a skin graft.  The appendages of the skin  Nails  Hairs  Sebaceous glands  Sweat glands  Nails A nail is a flat horny plate on the dorsal surface of tips of fingers and toes It has: Root: proximal edge (part embedded in skin) body: exposed part Nail fold: folds of skin surround and overlap the nail from side.  Nail bed is very vascular causing pink color of the nail  The germinative zone lies beneath the root& is responsible for growth of nail  Hairs  Covers most of the body surface except 1. Palm of hands 2. sole of the foot 3. Dorsal surface of distal phalanges of digits 4. Glans penis 5. Labia minora 6. inner surface of labia majora  Hairs Hair follicles: invaginations of the epidermis into the dermis, the hair grows out of these follicles (hair shaft). Hair bulb: the expanded extremity of the follicle Hair papilla: a vascular connective tissue that occupies the concavity of the bulb.  Arrector Pilli muscle  A band of smooth muscle connects the undersurface of the follicle to the superficial part of the dermis.  It is innervated by sympathetic nerve fibers.  It is involuntary.  Functions: 1. Its contraction causes the hair to move into a more vertical position. 2. It compresses the sebaceous gland and causes it to extrude sebum.  Sebaceous glands Function It secrets sebum to oil (lubricate) hair and skin. Sebaceous cyst It occurs because of the obstruction (blocking) of the sebaceous duct.  Sweat glands  long tubular glands with deep coiled part.  All over the body except 1. Red margins of lips 2. Nail beds, 3. Glans penis 4. Clitoris.  Skin infections Paronychia infection between the nail and nail fold Boil Infection of the hair follicle  CLINICAL CASE A 43-year-old woman comes to the physician because of a 1-day history of rash on the trunk and lower extremities. Three days ago, she visited a spa resort with multiple swimming pools. Examination shows multiple pustules (small blister or pimple on the skin containing pus)over the trunk and upper thighs. Inflammation of which of the following structures is most likely responsible for this patient's condition? A. Superficial epidermis B. Hair follicles C. Sebaceous glands D. Sweat glands https://next.amboss.com/us/questions/CdhvqH1-W/8 Fascia  Fascia superficial fascia: is a collection of connective tissue that lies under the skin where it is called. deep fascia: deeply situated where it invests the muscles and ensheathes blood vessels.  Superficial Fascia Is a loose 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 It may contain muscles as in: 1. The neck called platysma. 2. The scrotum, the superficial fascia is greatly replaced by the dartos muscle.  Contents of Superficial Fascia 1. Fat. 2. Cutaneous arteries. 3. Cutaneous veins. 4. Cutaneous nerves. 5. Superficial lymph vessels. 6. Subcutaneous muscles.  Functions of Superficial Fascia Acts as a bad conductor to heat Gives the full rounded appearance Facilitates the movement of the skin Provides as a good medium for the cutaneous vessels, nerves and lymphatics to form plexuses before they end in the skin.  Deep Fascia Is a 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 It may be thickened to form: 1. Retinacula. 2. Palmer and planter aponeurosis.  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.  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.  REFERENCE BOOK READING Clinical Anatomy by Regions, 10th edition, 2018 (LAWRENCE E. WINESKI). PAGES-29-30