Human Anatomy Introduction PDF

Summary

This document provides an introduction to human anatomy, focusing on skin, muscles, fascia, and cartilage. It details their structure, functions, and types. Diagrams illustrate key concepts.

Full Transcript

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

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