Lecture 2: Skin and Fascia

Departmen t of Anatomy Lecture 2 Basic tissues of the body (Skin and fascia) LECTURE OUTLINE To understand the general design and the basic structure of the human body. To know the different systems of the body. To understand the skin and its...

Departmen t of Anatomy Lecture 2 Basic tissues of the body (Skin and fascia) LECTURE OUTLINE To understand the general design and the basic structure of the human body. To know the different systems of the body. To understand the skin and its appendages. To understand the fasciae and its modifications. LECTURE ILOs 1. Identify different body structures, different systems and organs of the human body 2. Determine the structure and functions of the different systems of the human body with reference to the clinical significance of each.  BASIC STRUCTURE OF HUMAN BODY  Tissues of the body Epithelial tissue. Connective tissue: Non-specific connective tissue. binds and supports different organs together. Specific connective tissue: Blood. Cartilage. Bone. Muscular tissue. Nervous tissue.  Epithelium Connective tissue Development from the 3 germ layers from the mesoderm Cells closely packed widely separated Matrix minimal abundant Free surface Usually present Has no free surface Basement Present Absent membrane Vascularity Avascular Highly vascular (except hyaline cart.) Classification 1-Covering or lining 1- CT proper (non-specific) 2-Glandular 3-Neuroepithelium 2- Specific CT (bone, cartilage, blood) Example epidermis of skin dermis of skin  BASIC STRUCTURE OF HUMAN BODY Skin. Fasciae: Superficial. Deep. Muscles. Blood vessels and lymphatics. Bones. Joints. Bursae. 1 2 Synovial sheaths.  BASIC STRUCTURE OF HUMAN BODY Blood vessels: Arteries, branches, arterioles, anastomosis, end arteries…. Veins, tributaries, venules, plexuses. venae comitants, portal. Capillaries, sinusoids. Arteriovenous anastomosis. Lympatic system Lymph vessels. Lymph nodes. Lymph trunks. SKIN  SKIN Function Structure Epidermis (superficial part) Dermis (deep part) Collagen fibers and the lines of cleavage (Langer’s lines) Skin creases Skin appendages Skin glands Skin pigments  Functions of the Skin Appearance and shape (contour) of the body Protection from: infections, hot, cold, sun (UV), chemicals, water loss, …… Regulates body temperature Sensations: hot, cold, touch and pain Production of Vitamin D  FUNCTIONS OF THE SKIN The skin protects the body against invasion by microorganisms and protects underlying body structures and delicate tissues from injury The pigment melanin, which provides color to the skin, further protects the skin from the harmful effects of the ultraviolet rays of the sun The skin regulates body temperature by protecting the body from excessive loss of heat and fluids from underlying tissues The skin serves as a sensory receptor for sensations such as touch, pressure, pain, and temperature The skin provides for elimination of body wastes in the form of perspiration. substances such as water, salts, and some fatty substances are excreted through the skin The skin is responsible for the first step in the synthesis of vitamin D, which is essential for bone growth and development Structure of the Skin: (2 layers-epidermis and dermis) Epidermi Horny layer (Keratin) s Germinative layer Papillary layer Dermis Reticular layer  Dermis Papillary Layer Nourishes and supports epidermis. Responsible for finger prints Reticular Layer Restricts spread of pathogens penetrating epidermis. Stores lipid reserves. Attaches skin to deeper tissues. Sensory receptors detect touch, pressure, pain, vibration, and temperature. Blood vessels assist in thermoregulation Contains lines of cleavage (Langers lines) Finger prints Lines of cleavage of the skin (Langer’s lines)  SKIN PIGMENTS Melanin (Brown-black) Carotene (Yellow) Hemoglobin (Pink)  Melanocytes Melanocytes ( ML-an-Õ-sits or me-LAN-Õ-sits) synthesize and store a Brown pigment, melanin (MEL-a-nin), that gives the tissue a dark color. Melanocytes are common in the epithelium of the skin, where they play a major role in determining skin color. They are also found in the underlying connective tissue (the dermis), although their distribution varies widely. Due to regional, individual, and racial factors.  Skin Appendages Hair Nails Glands: Sebaceous glands Sweat glands Wax gland Mammary gland  Hair follicle A) HAIR Supplied by sympathetic fibers  Hair Color and Texture Hair color is determined by the amount and type of melanin present. Melanocytes become less active with age. Gray hair is a mixture of pigmented and non pigmented hairs.  Hair Color and Texture Red hair results from a modified type of melanin contains iron. The shape of the shaft determines its texture: Round shaft - straight hair. Oval shaft - wavy hair. Flat shaft - curly or kinky. Alopecia = hair loss. B) Nails Protect and support tips of fingers and toes Skin Creases and Nails FASCIA  FASCIA Superficial Deep Function Function Characters Characters Contents Contents Superficial and deep Fasciae Superficial fascia Deep fascia Intermuscular septum SUPERFICIAL FASCIA  Characters Under skin Loose fibroareolar (fat)  Function 1. Movement of skin 2. Soft pads 3. Media for nerves and blood vessels 4. Regulation of body temperature 5. Cutaneous skeletal muscles (platysma) 6. Binds skin to underlying tissues (palm, sole)  Contents 1. Superficial veins 2. Mammary gland 3. Lymph nodes 4. Cutaneous nerves 5. Sweat glands  Modifications of deep fascia Aponeurosis: Palmar and planter, aponeurosis of the external oblique muscle. Fibrous septa Intermuscular septum. Ligaments Retinacula Flexor and extensor retinacula. Fibrous sheaths Fibrous flexor sheath, carotid sheath and femoral sheath. Bursae Deep fascia: aponeurosis External oblique aponeurosi s Biceps aponeuros is Deep fascia: aponeurosis and Flexor retinaculum Retinaculum Palmar Aponeurosis  Difference between superficial and deep fascia Superficial fascia Deep fascia 1. Loose fibro-areolar full of fat Dense white fibrous – no fat 2. Medium for passages of nerves and vessels No medium 3. Situated under the skin (subcutaneous) and Situated under the superficial one and covers internal facilitate movement of the skin structures 4. Functions: Functions:  Contain blood vessels and nerves  Keep contour of the body  Fat distribution and conservation of body  Blends with periostium of bones heat  Gives muscular attachment  Movement of the skin  Thickened to form retinacula, aponeurosis and  Contain sheets of cutaneous muscles ligaments  Contains the mammary gland  Forms intermuscular septa  Facilitate circulation by compressing the veins References: 1- Susan Standring (2020). Gray's anatomy 42nd edition. 2- Gerard J. Tortora and Mark T. Neilsen: Principles of Human Anatomy (12th edition)