Human Anatomy Introduction PDF

INTRODUCTION BASIS OF HUMAN ANATOMY 1  SKIN Structure of the skin: The skin is formed of two layers: the superficial Layer is called the epidermis; and the deep layer is called the dermis. 1-Epidermis: formed of keratinized epithelium. 2-Dermis: fo...

INTRODUCTION BASIS OF HUMAN ANATOMY 1  SKIN Structure of the skin: The skin is formed of two layers: the superficial Layer is called the epidermis; and the deep layer is called the dermis. 1-Epidermis: formed of keratinized epithelium. 2-Dermis: formed of connective tissue rich in collagen and elastic fibers. Through the dermis pass blood vessels and nerves which supply the skin. Skin appendages: 1-Hair: Formed of root (follicle) and shaft. A small muscle called arrector pili muscle is attached to the hair follicle and its contraction pulls the hair to into a vertical position. 2-Nails: Are keratinized plates on the dorsal surfaces of fingers and toes tips. Each nail is formed of root and body which lies on the nail bed.. 3-Sweat glands: Are long, tubular and spiral glands. Their ducts open on the skin surface by pores. They secrete sweat. 4-Sebaceous glands: Are attached to the hair follicles, and their ducts open into the hair follicles. They secrete oily secretion called sebum. 2 Skin pigments: The color of the skin is determined by pigments mainly by Melanin, which is a brown-black pigment formed by special cells present in the skin called melanocytes. Skin color can be influenced by other pigments as Hemoglobin (red pigment). Function of the skin: -Protection of the underlying structures by providing a barrier against mechanical, physical and chemical injury. -Protection from microorganisms, preventing them from entering the body. -Sensation: skin contains receptors for different sensations as touch, temperature and pain. -Heat regulation: by sweating and vasodilatation in hot weather and by vasoconstriction in cold weather. -Synthesis of vitamin D. 3  FASCIA It is a collection of connective tissue deep to the skin. It is divided into two layers: 1-SUPERFICIAL FASCIA: It is also called hypodermis or subcutaneous layer. It lies immediately deep to the skin. It is formed of loose connective tissue that contains a variable quantity of fat (less in thin and more in overweight). Functions of superficial fascia: 1-Smoothens and softens the body surface. 2-Act as heat insulator prevent heat loss. 3-Act as reservoir of fat (energy store). 2-DEEP FASCIA: It is formed of strong non-elastic fibrous tissue. It is absent in the face and is very thick in palm and sole. Functions of deep fascia: 1-It forms a sheet that fix underlying structures in position. 2-It is very thick at in the palm of hand and the sole of foot. 3-It forms intermuscular septa (between muscles) and interosseus membranes (between bones). 4  MUSCLES Muscle tissue is characterized by the property of contraction. Classification of muscles: 1-Skeletal muscles: They are attached mainly to the skeleton. They are voluntary (supplied by somatic nerves). 2-Cardiac muscles: They are present in the heart. They are involuntary (supplied by autonomic nerves). 3-Smooth muscles: They are present in the wall of blood vessels and viscera. They are involuntary (supplied by autonomic nerves). Skeletal muscles attachment: 1-Origin: The most fixed attachment. 2-Insertion: The most mobile attachment. 5 Origin and insertion may be: FLESHY: Muscles are attached to bone by fleshy fibers. TENDONS: Muscles are attached to bone by tendon formed of bundles of collagen fibers. APONEUROSIS: Muscles are attached to bone by aponeurosis which is a flat expanded tendon. CARTILAGE: Muscle are attached to cartilage as muscles of the larynx. SKIN: Muscles are attached to skin as muscles of the face. Skeletal muscles innervation: 1-Motor innervation: carry nerve impulses responsible for muscle contraction. 2-Sensory innervation: carry proprioceptive sensation (sense of movement) from the muscle. Skeletal muscles actions: 1-Prime mover: The muscle which initiates and maintains the movement. 2-Synergists: The muscles which the help prime mover to do the action. 3-Antagonists: The muscles which oppose the action of prime mover. 6 Important skeletal muscles of the body: 7  CARTILAGE It is a rubbery type of connective tissue. It is tough and resilient. It is devoid of blood vessel and nerves. It is surrounded by perichondrium. There are three types of cartilage: A- Hyaline Cartilage: Structure: It is formed of numerous cartilage cells (chondrocytes), matrix and few fibers. It is homogenous and translucent. It may ossify at old age. Present in: -In the developing bones. -In the articular cartilage. -In the larynx (except epiglottis), Larynx tracheal rings. Costal cartilage Trachea B- White Fibrocartilage: Structure: It is formed of matrix rich in white collagen fibers. Present in: -Intervertebral discs C-Yellow Elastic Fibrocartilage: Structure: It is formed of matrix rich in yellow elastic fibers. Present in: -Auricle of the ear. -Tip of the nose. -Epiglottis. 8  BONES It is the hardest form of connective tissue. It is composed of bone cells, collagen fibers and inorganic salts mainly calcium. Functions of the skeleton: 1-Gives shape to the body. 2-Supports the body weight. 3-Protects the vital organs, e.g. -the skull protects the brain -the thoracic cage protects the heart and lungs 4-Forms the joints that allow movements. 5-Forms the blood cells in the bone marrow. CLASSIFICATION OF THE SKELETON: A-According to their position in the body: AXIAL SKELETON: Head and neck; thorax and back: Skull, hyoid bone, sternum, ribs (12 on each side) and vertebrae which are divided into: Cervical (7); Thoracic (12); Lumbar (5); Sacral (5) & Coccygeal (3-5). APPENDICULAR (PERIPHERAL) SKELETON: In the upper and lower limbs. Bones of the upper limb: -Shoulder → Clavicle (anteriorly), Scapula (posteriorly) -Arm → Humerus -Forearm → Ulna (medially), Radius (laterally) -Hand → Carpal, Metacarpal and Phalanges Bones of lower limb: -Pelvis → Hip bone -Thigh → Femur -Leg → Tibia (medially), Fibula (laterally) -Foot → Tarsal, Metatarsal and Phalanges 9 B-According to their shape: 1-LONG BONES: -E.g.: humerus and femur. Long bones have two ends called epiphyses, and a shaft called diaphysis in between. The shaft contain a tubular cavity inside called medullary cavity which contains bone marrow. In growing long bones, between the epiphysis and the diaphysis, there is a disc of cartilage called “epiphyseal plate” responsible for bone growth in length. 2-SHORT BONES: E.g.: carpal bones (in hand) and tarsal bones (in foot). 3-FLAT BONES: E.g.: the bones forming roof of the skull, sternum and scapula. Sternum 4-IRREGULAR BONES: E.g.: vertebrae. 5-PNEUMATIC BONES: Bones contain air cavities; E.g. bones around the nose 6-SESAMOID BONE: Bones inside tendons; E.g. patella 10  Bones are covered by periosteum. The outer layer of bones is formed of compact bone with cancellous (spongy) bone inside. The ossification of bones is either by intra-cartilagenous ossification (eg long bones & base of the skull); while others ossify by intra-membranous ossification (eg vault of the skull). Bones of the body: 11  JOINTS Joint is the contact between two or more bones. Classification of Joints: 1-FIBROUS JOINTS: The surfaces of the bones are connected together by a fibrous tissue. They are fixed or immobile joints. E.g.: -Sutures: Present between the bones of the skull. -Gomphosis: (Peg & socket); Present between teeth & their sockets. 2-CARTILAGENOUS JOINTS: The surfaces of the articulating bones are connected together by cartilaginous tissue. Eg: intervertebral disc. 3-SYNOVIAL JOINTS: It is a freely mobile joint. Structure of the synovial joint: -Fibrous capsule: surrounds the synovial joint, it is lined by a synovial membrane, which secretes synovial fluid into the joint cavity, which lubricate movements. -Articular cartilage: covers articular surface of bone. -Ligaments: are tough bands of connective tissue support and strengthen the joint. -Bursae: are small fluid-filled sac located between joint and surrounding structures, to prevent friction during movement. 12 Types (Varieties) of the Synovial Joints 1-Uni-axial joints: Allow movement around one axis e.g.: - Pivot joint: e.g. atlanto-axial joint. - Hinge joint: e.g. elbow. 2-Bi-axial joints: Allow movement around two axis e.g.: -Condylar (Bicondylar) joint: e.g. temporomandibular joint (TMJ). -Ellipsoid joint: e.g. wrist joint. 3-Multi-axial joints: Allow movement around multiple axis e.g.: -Ball and socket: e.g. shoulder and hip joints. 13  IMPORTANT JOINTS OF THE UPPER LIMB: -Shoulder joint: between scapula and humerus -Elbow joint: between humerus above and radius & ulna below -Wrist joint: between radius above and carpal bones below IMPORTANT JOINTS OF THE LOWER LIMB: -Hip joint: between acetabulum of hip bone and head of femur -Knee joint: between femur, tibia and patella -Ankle joint: between tibia, fibula and talus MOVEMENTS OF THE JOINTS: -Flexion: Bending; approximation of two ventral surfaces. -Extension: Straightening; move two ventral surfaces away from each other. -Adduction: Movement towards the midline. -Abduction: Movement away from the midline. -Rotation: Medial or lateral rotation of the limb around a vertical axis. 14  MOVEMENTS OF THE TMJ: -Elevation: Moving mandible up. -Depression: Moving mandible down. -Protraction: Moving mandible forwards. -Retraction: Moving mandible backwards. -Side to side movement: Moving mandible from side to side. 15