Introduction to Anatomy PDF

Introduction of anatomy Anatomy of the musculoskeletal system (MSK) The Skeleton – General Points Adult skeleton made up of 206 bones - 8 (cranial), 6 * (auditory ossicles), 14 (facial) , 26 (vertebral column), 26 (hyoid, sternum & ribs), 64 (upper limb) & 62 (lower limb) Bones – vary in s...

Introduction of anatomy Anatomy of the musculoskeletal system (MSK) The Skeleton – General Points Adult skeleton made up of 206 bones - 8 (cranial), 6 * (auditory ossicles), 14 (facial) , 26 (vertebral column), 26 (hyoid, sternum & ribs), 64 (upper limb) & 62 (lower limb) Bones – vary in shape and size * Each bone links with others to form a sturdy, flexible * framework Structure of the skeleton designed to * give shape to the individual support the soft tissues of the body protection for vital organs Specific groups of bones, powered by attached muscles, * provide leverage for making a wide range of coordinated movements Bones – Points of Practical Interest Constituents of bone (35% organic & 65% inorganic) Amount of the two constituents varies at different periods of life In a child : organic (50%) : inorganic (50%); injury may cause bones to bend (elasticity) or only partially broken (fracture!) Aged : large proportion of inorganic and organic material deficient in quantity & quality; bones are more # brittle & hence Relative proportion of two constituents also differs in different bones; more inorganic in petrous part of the temporal bone than in the squamous part; bones of the limbs contain more inorganic than those of the trunk  The Skeleton - Divisions Bilaterally symmetrical Two main divisions the axial skeleton the appendicular skeleton The two divisions have different roles axial skeleton (mainly protective role for some of the body’s vulnerable & vital parts appendicular skeleton (main role is to provide the body with mobility) The Axial Skeleton Bones of the central part of the body Include the skull, the vertebral(spinal) column, the ribs and the sternum Skull – encases brain Vertebral column – encases the spinal cord Ribs – cage around the heart & lungs The Appendicular Skeleton Bones include those of the upper and lower limbs Include the scapulae (shoulder blades) and the pelvis – linking structures between limbs and the axial skeleton  Functions of Bone Bones perform mechanical functions of support, protection and body movement and physiological functions of haemopoiesis & mineral storage Support – rigid framework Protection – enclose vital structures & viscera Body movement – anchoring attachments for most muscles; act as levers with joints functioning as pivots when muscles contract to cause movement Haemopoiesis – in red marrow Mineral storage – in bone matrix  Types of Bones – General Shape Mechanical purposes determine different forms Long bones – in the limbs (e.g. clavicle, humerus, femur, metacarpals, metatarsals & phalanges); - form a system of levers which sustain weight of the trunk & enable locomotion - length greater than width, tubular shaft (diaphysis) & usually an epiphysis at each end; Short bones – in the hand (e.g. scaphoid, lunate) and feet (e.g. talus, calcaneum); - for strength & compactness & slight/limited movement - roughly cuboidal in shape & mainly spongy with a thin compact crust  Types of Bone – General shape Flat bones – in the vault of the skull (e.g. frontal, parietal); scapula is included in this category - principle requirement is either protection &/or provision of broad surface for muscle attachment - composed of two thin layers of compact bone enclosing a layer of spongy bone (diploe) Irregular bones – bones of the facial skeleton, vertebrae and pelvic bones - external layer of compact bone & spongy within Sesamoid bones – found in tendons where they rub over bony surfaces Types of Bone – General shape  Surface Markings of Bones Found where fascia, ligaments tendons or aponeuroses are attached to bone Surfaces show various markings &/or irregularities (surface raised or roughened) Not present at birth; appear at puberty & become progressively more obvious in adult life Pull of fibrous structures causes the periosteum to be raised and new bone is deposited beneath Pressure on bone surface – may cause a groove, fossa, notch; local bone resorption In some cases, surface markings are large; given special names (e.g. tuberosity, malleolus, trochanter, epicondyle, etc.)  Bone Marrow & Periosteum Found in marrow cavities of long & short bones and in between bony trabaculae of cancellous bone in flat & irregular bones At birth, marrow is red (haemopoiesis); blood forming activities gradually lessens with age – red marrow replaced by yellow (fatty) marrow In the adults, red marrow restricted to bones of the skull, vertebral column, thoracic cage, pectoral & pelvic girdle bones & head of humerus & femur Periosteum covers all bone surfaces, except at joints; has abundant vascular and nerve supply & the deep layer is osteogenic; sensitive (pain when traumatised) Periosteum firmly fixed at sites where muscles, tendons and ligaments are attached to bone; Sharpey’s fibre Injuries to Bone – Common Fractures (Upper Limb) Clavicular fracture Fracture of the surgical neck of humerus Fracture of the shaft of the humerus Supracondylar fracture of the humerus Fracture of the olecranon process Fracture of the distal end of the radius (Colles’ fracture) Fracture of the scaphoid bone Injuries to Bone – Common Fractures (Upper Limb) Injuries to Bone – Common Fractures (Lower Limb) Fracture of the femoral neck (intracapsular) Intertrochanteric / pertrochanteric fracture (extracapsular) Fracture of the femoral shaft Tibial shaft fracture Fracture of the fibular neck & shaft Fracture of the lower end of the tibia and fibula Injuries to Bone – Common Fractures (Lower Limb)  Joint – point at which two bones meet (articulation), whether or Joints not movement occurs between them Classified according to the tissues that lie between them (by structure) or by the way they move Various types of joints Fibrous joints (no movement) Cartilaginous joints (primary & secondary) Synovial joints (freely moveable)  Structures that form Joints Bone – fundamental element of all joints; the extremities in long bones; in flat bones at the edges; by various parts in short bones Cartilage – at the articular surfaces in long bones; all around the surfaces of short bones; Fibrocartilage – white fibrous (collagen for strength & toughness) & cartilaginous (elasticity); arrangement varies – interarticular (menisci); interosseous (occur as discs at joints with slight mobility – intervertebral joints & symphysis pubis); circumferential rims (occur as rims around some articular cavities; shoulder & hip joints) Ligament – found in nearly all moveable joints; bundles of collagen fibres; pliable & flexible but strong & inextensible; some ligaments contain elastic fibres Synovial membrane – thin secretory membrane; articular – in freely moveable joints; bursal – found interposed between surfaces that move upon each other (producing friction as in gliding of a tendon or of skin over bone surfaces – may be subcutaneous (e.g. pre-patellar, over the olecranon or deep-seated (e.g. between gluteal muscles or over bony trochanter) & those near near a joint may communicate with the joint cavity)  Fibrous Joints - Features Articulating surfaces joined by fibrous tissue Degree of movement depends upon the length of collagen fibres between the bones E.g. Sutures of the vault of skull; inferior tibiofibular joint*  Cartilaginous Joints - Features Two types - 1º & 2º 1º (Primary) – bones united by a plate of hyaline cartilage (e.g. epiphyseal plate of a growing bone & 1st rib & manubrium sterni); no movement 2º (Secondary) – bones united by a plate/disc of fibrocartilage & joint surfaces covered by hyaline cartilage (e.g. inter-vertebral joints(IVJ) symphysis pubis); small amount of movement  Synovial Joints - Features Also called freely movable joints Articular surfaces covered by hyaline cartilage separated by a joint cavity; this arrangement permits a great degree of freedom of movement Cavity lined by synovial membrane that extends from the margin of the one articular surface to that of the other Protected on the outside by a tough fibrous tissue – capsule Joint surfaces are lubricated by viscous synovial fluid; produced by the synovial membrane In some joints, such as the knee joint, discs (articular discs) of fibrocartilage are found between joint surfaces Fatty pads lie between synovial membrane and fibrous capsule in some joints(e.g. hip & knee joints)  DEGREE OF MOVEMENT Limited by the shape of the bones Coming together of adjacent anatomical structures (e.g. flexion of the thigh against the anterior abdominal wall) Presence of ligaments uniting the bones – e.g. extra- & intra-capsular ligaments (e.g. cruciate ligaments)  Types of Synovial Joints (by arrangement of articular surfaces & types of movement) Hinge – permit flexion & Pivot – allow rotation; a extension only (e.g. elbow round bony process fits into a bony ligamentous socket (e.g. joint) atlantoaxial joint & proximal Radio-ulnar joint) Saddle – concave & convex Condyloid – permit flexion & joint surfaces (e.g. 1st MPJ) extension, adduction, adduction & circumduction Plane – permit gliding or (e.g. MPJ) Ball & Socket – permit sliding movements (e.g. movement in several axes; a rounded head fits into a acromioclavicular joint) concavity (e.g. shoulder & hip joints) Depends on 3 main factors Shape, size & arrangement of Stability of Joints articular surfaces – e.g. hip joint & ankle joint Ligaments – prevent excessive movement; if stresses continue, ligaments stretch – e.g. ligaments between the bones that form the arches of the foot are dependent upon the tone of muscles, impairment of muscles by fatigue > ligaments stretch > arches collapse > flat feet Tone of muscles – major factor – e.g. tone of the rotator cuff muscles keeps the head of humerus in the shallow glenoid cavity of the scapula; loss of tone, shoulder joint will dislocate  Neurovascular Supply to Joints Capsule & ligaments receive abundant sensory supply Nerve supplying the joint also supplies the muscles moving the joint & overlying skin (Hilton’s law) Stretching of the capsule and ligaments produces reflex contraction of muscles around the joint; excessive stretching produces pain Stretch receptors in the capsule & ligaments – proprrioception information to CNS for position of joints; information from muscle & tendons supplements – maintains postural tone and co-ordination of voluntary movement Rich network of blood vessels around the joint (periarticular network or anastomoses); blood vessels innervated by sympathetic fibres – control blood supply  Closed fibrous sacs containing viscous Bursae associated fluid with joints Found where tendons rub against bones, ligaments or other tendons Commonly found close to joints where the skin rubs against underlying bony surfaces; occasionally the cavity of the bursa communicates with the cavity of a Shoulder synovial joint joint Inflammation of the bursa may result from repeated and/or excessive trauma – “housemaid’s knee”, “clergyman’s knee”, “miner’s knee”, “student’s elbow” (pre-patellar bursitis, olecranon bursitis, subacromial bursitis, etc.)  Injuries to Joints Dislocation – disruption of joint in which normally opposing surfaces have no contact Fracture – a structural break in the continuity of bone Sublaxation – disruption of joint in which normally opposing surfaces have partial contact Ligament Tears Injuries to Joints–Dislocation/Fracture Surgical neck fracture of humerus Injuries to Joints – Dislocation & Sublaxation Dislocation – disruption of joint in which normally opposing surfaces have no contact Sublaxation – disruption of joint in which normally opposing surfaces have partial contact Injuries to Joint – Ligament Tears  Other Injuries to Joints Degenerative joint diseases arthritis (osteoarthritis & rheumatoid arthritis) Joint infection Haemoarthrosis (blood within synovial cavity) Joint effusions (excessive synovial fluid accumulation within the joint cavity) THANK YOY