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SKELETAL SYSTEM ○ Squamosal (between parietal and temporal) Introduction ○ Lamboidal (b...

SKELETAL SYSTEM ○ Squamosal (between parietal and temporal) Introduction ○ Lamboidal (between parietal and A strong, yet light internal support for the human occipital) body. Other skull sutures connect facial bones and are Adapted for the protection, locomotor, and named after these structures. manipulative functions. The upright stance increases the ability of the VERTEBRAL COLUMN: skeletal muscle to resist gravity. GENERAL CHARACTERISTICS The skeleton maintains its upright position through Formed frok 26 irregular bones a series of compensating curves. It contains four distinct curvatures. The skeleton accounts for approximately 20% of It provide axial support for the trunk the body mass. Transmits weight of trunk to lower limbs 206 bones of the body are grouped into the axial Protects spinal cord and appendicular skeleton. Attachment site for ribs and muscles AXIAL SKELETON Separated by intervertebral discs Forms the long axis of the body There are 24 vertebrae, a sacrum (5 fused) and a 80 bones in three major regions: coccyx (4 fused) ○ Skull ○ Vertebral column CHARACTERISTICS ○ Bony thorax Cervical (C1 - C7) Ribs ○ Neck/movable Sternum Thoracic (T1 - T12) APPENDICULAR SKELETON ○ Rib cage/limited movement Bones of upper and lower extremities and girdles. Lumbar (L1 - L5) 126 bones in three major regions: ○ Lowback/movable ○ Girdles Sacral (5 fused) Shoulder girdle ○ Joins the pelvis Pelvic girdle Coccyx (4 fused) ○ Upper extremity ○ Terminus ○ Lower extremity CLINICAL DEVIATIONS PHYSIOLOGICAL FUNCTIONS OF BONES Scoliosis Calcium storage and release ○ An abnormal lateral curvature of the Phosphate storage and release spinal column Production of blood cells ○ Curvature can occur in an “S” or “C” deviation. THE SKULL Lordosis Body most complex body structure ○ Accentuated lumbar curvature Formed by two sets of bones, the cranial bones ○ Being overweight or pregnant causes an and the facial bones. excessive load up front. These 22 bones combine to form the cranial cavity and the facial features. CHARACTERISTICS - LIGAMENTS In addition, there are 3 bones of the inner ear to Ligaments hold the vertebral column in an upright assist in sound transmission. position ○ The broad anterior longitudinal ligament THE SKULL: Introduction prevents hyperextension and is quite The bones of the skull provide; strong ○ A case t0 house the brain, the cranium ○ The cord like Posterior longitudinal ○ A framework for the face ligament prevents hyperflexion and is ○ Cavities to house to house the organs of relatively weak sight, taste, and smell. ○ Passages for air and food INVERTEBRAL DISCS ○ Attachment sites for the teeth Intervertebral discs are cushion like pads ○ Attachment sites for muscle interposed between vertebra Most of the bones of the skull are flat bones The discs provide elasticity and compressibility Except for the mandible, all bones are firmly united Compression flattens discs by inter locking sutures Discs are thickest in the cervical and lumbar to The major sutures of the skull are; provide flexibility ○ Coronal (between frontal and parietal) Coccyx articulates with sacrum ○ Sagittal (between parietal bones) THE STERNUM The sternum lies in the anterior midline of the THE PELVIC (hip) GIRDLE thorax Attaches the lower limbs to axial skeleton It is three fused bones Transfers the weight of the torso, head, and upper ○ Manubrium extremities to lower limbs Jugular notch Supports the visceral organs of the pelvis Clavicular notch Secured by strong ligaments and deep sockets the ○ Sternal body joint is reinforced for stability Sternal angle Less range of motion in all planes of movement ○ Xiphoid process Female pelvic structures to facilitate childbearing Xiphisternal joint RIBS PELVIS Pelvic girdle is formed by a pair of coxal bones, each called an os coxae. Each os coxae unites anteriorly at the pubic symphysis and with the sacrum posteriorly Each coxa is formed by the ilium, ischium and pubic which were separate during childhood but fused in adulthood Collectively the os coxae, sacrum and coccyx is called the pelvis. Os Coxa Ilium - superior THE APPENDICULAR SKELETON Ishium - posterior Appended to the axial skeleton Pubis - anterior Pectoral girdle is for manipulation and is a lighter, less heavily reinforced structures Pelvic girdle is for weight bearing and locomotion and is a heavier, more robust structure Differences appear in bone structure, joint structures, ligaments and muscle PECTORAL OR SHOULDER GIRDLE Consist of two bones, the anteriorly positioned clavicle and the posteriorly positioned scapula Pectoral girdle is a loosely attached, held in place largely by musculature attached to the thorax and the vertebral column Only direct ligament attachment exist at the sternoclavicular joint Frees girdle to move over the thorax as the need THE LOWER LIMB arises Thigh - Femur Leg THE UPPER LIMB ○ Tibia (mataba) Arm - Humerus ○ Fibula (payat) Forearm - Ulna and Radius Foot (7 Tarsal bones) Hand Instep (5 Metatarsal bones) Wrist (8carpal bones) Toes (14 Phalanges) Palm (5 metacarpal bones) Fingers (14 phalanges) TARSAL BONES THE HUMERUS Talus - ankle bone Calcaneus - heelbone (largest tarsal bone) Cuboid - cube shape, most lateral tarsal bone. Navicular - little ship Cuneiform - 3 bones, wedge shape, medial, intermediate, lateral. JOINT/ARTICULATIONS Ball and socket - full freedom of movement. (Hip and shoulder joints)  Gliding - one bone glides or moves over the other. All muscle cells are elongated cells and are (Between carpals) referred to as muscle fibers. Pivot - movt in long axis. (Radius and ulna) Muscle contraction depends om two types of Biaxial - 2 planes at right angles filaments actin and myosin. Hinge - one direction All prefixes of myo or mys and sarcoreference Condyloid - movt in all planes but no axial muscle. rotation. (Wrist, radius, ulna) SKELETON MUSCLE TISSUE DEVELOPMENTAL ASPECTS OF THE SKELETON Skeletal muscle tissue appears as distinct muscle Fontanels that attach to the skeletal system. Spinal Curvatures It has obvious striations Long bone ratio It is voluntary muscle under conscious control Changes in Female Pelvis Skeletal muscle cells run to the full length of a Adult skeletal changes muscle Line A show the width of one cell (fiber) SKELETAL DISORDERS Note that striations characteristics of this muscle Injury, degenerative wear and tear, and inflammatory type disorders affect joints. These cells are multicellular, B marks one nucleus. Sprains are common injuries that cause ligaments to rip of Location: muscle associated with the skeleton separate from the bone. Function: voluntary movement Tendinitis (such as teniss elbow) and bursitis are Muscle are connected to bones by tendons. inflammations of the tendon sheaths. CARDIAC MUSCLE TISSUE Osteoarthritis - is degenerative condition associated with Cardiac muscle occur only in the heart the wearing away of the protective caps of cartilage covering The muscle is striated but involuntary the bone-ends. Bony growths or spurs develop as the Cardiac fibers are short, fat, branched, and cartilage degenerates, causing restriction of movement and interconnected. pain. The cause is not known and may just be wear and tear Cardiac muscle cells are interlocked by associated with aging. intercalated discs are function as a single unit. Cardiac muscle cells branch, are striated, are Rheumatoid arthritis - is a severely damaging arthritis that uninucleate (B) and have intercalated discs (A) begins with inflammation and thickening of the synovial Location: HEART membrane followed by bone degeneration and Function: involuntary, rhythmic contraction disfigurement. More women than men are affected. There SMOOTH MUSCLE TISSUE may be a genetic predisposition to rheumatoid arthritis. Joint It is found in the walls of hollow organs such as the replacement may in some cases restore function. stomach, urinary bladder, and intestines. It has no striations MUSCULAR SYSTEM It is not subject to voluntary control Key concepts; Smooth muscle cells are spindle shaped and Muscles generally function to allow movement, uninucleate. (B) adjust posture, and produce body heat. Location: walls of hollow organs, i.e. stomach, The crucial properties of muscle tissues are its intestine, uterus, ureter ability to contract, be excited by a stimulus, be Function: involuntary movement - i.e. churning of stretched, and return to its original shape after food, movement of urine from the kidney to the stretching or contracting. bladder, partuition. Skeletal muscles give the skeleton power to move, DIFFERENCES IN CONTRACTIONS cardiac muscle is found only in the heart and it's Skeletal muscle can contract rapidly but tired and specialized anatomy and physiology give it a must be rested unique method of contracting and relaxing, smooth ○ Skeletal muscle contraction vary in force muscle is typically involved with involuntary depending on use rhythmic contraction of internal organs. Cardiac muscle contracts at a steady rate but can accelerate to cope with demand. MUSCLE AND MUSCLE TISSUE Smooth muscle contracts un steady, sustained Overview of muscle tissue; contractions and continues on tirelessly. There are three types of muscle tissue MUSCLE FUNCTION ○ Skeletal muscle Muscle performs four important functions in the ○ Cardiac muscle body: ○ Smooth muscle ○ Producing movement These muscle tissues differ in the structures of ○ Maintaining posture their cells, their body location, their functions, and ○ Stabilizing joints the means by which they are activated to contract. ○ Generating heat  Muscle fibers predominate the tissue but it PRODUCING MOVEMENT contains blood vessels, nerve fibers, and Movement results from muscle contraction connective tissue Skeletal muscle are responsible for all locomotion CONNECTIVE TISSUE WRAPPINGS and manipulation Each muscle fiber is wrapped by the sheath of Allow to interact or react with your external areolar connective called endomysium environment Several fibers are gathered side by side into It controls eye movement, facial expressions,. bundles called fascicles circulation, and moves gas, liquids, and solids Each fascicle is bound by collagen fiber layer through organs. called the perimysium. MAINTAINING POSTURE Fascicles are bound by a dense fibrous connective Skeletal muscles are utilized constantly to tissue layer called the epimysium maintain sitting, standing, and moving postures. The epimysium surrounds the entire muscle Postural muscle develop to compensate for the External to the epimysium is the deep fascia that never ending pull of gravity binds muscles into functional group. ○ Our developmental milestones as an All the connective tissue layers are continuous infant our initial victories over gravity with one another as well as with the tendons that Curves of the spinal column are shaped by the join muscle to bone interplay of skeletal muscle and gravity When muscle fibers contract they pull these STABILIZING JOINTS connective tissue sheaths which in turn transmit Skeletal muscle provide the dynamic stability of the force to the bone to be moved joints Connective tissue support each cell Many joints are poorly reinforced by ligaments and MICROSCOPIC ANATOMY connective tissue Muscle fibers - individual specialized cells Many joints have no complementary surface which Myofilaments - smaller fibers of the muscle fiber do not contribute to stability. Myosin - thick myofilaments GENERATING HEAT Actin - thin myofilaments Muscles generate heat as they contract Sarcolemma - plasma membrane The heat generated is vitally important to maintain Sarcoplasm - cytoplasm normal body temperature Sarcoplasmic reticulum - like the ER Skeletal muscle generates most of the heat Sarcomere - fundamental unit of muscle because it represents 40% of the body mass contraction. Excess heat must released to maintain body A Band - darks bands of the skeletal muscle fibers temperature I Band - light bands of the skeletal muscle FUNCTIONAL CHARACTERISTICS consisting only od actin myofilaments Excitability or Irritability Z lines - dark lines that can be seen in the middle ○ It has the ability to respond to a stimulus of the I Bands. It is a network of protein fibers Contractility forming attachment site for actin myofilaments. ○ It has the ability to shorten forcibly H zone - a second light zone at the center of each Extensibility sarcomere which consist only of myosin filaments. ○ Muscle fibers can be stretched NERVE AND BLOOD SUPPLY Elasticity Normal activity of skeletal muscle is totally ○ Resume its normal length after being dependent on it's nerve and blood supply. shortened. Each skeletal muscle fiber is controlled by a nerve endings SKELETAL MUSCLE Contracting muscle fiber use huge amounts of energy which requires a continuous supply of oxygen and nutrients In general, eacg muscle is served by an artery and one or more veins. ATTACHMENT Most muscles span joints and have at least two attachments Origin ○ Attachment of a muscle that remains relatively fixed during muscular ANATOMY OF A SKELETAL MUSCLE contraction Each skeletal muscle is a discrete organ with ○ Generally a more proximal or axial thousands of fibers location Insertion  ○ Attachment of a muscle that moves during muscular contraction ○ Generally a more distal or appendicular attachment Direct attachments have the epimysium attaching directly to the periosteum of the bone or perichondrium of a cartilage. Indirect attachments have the epimysium attaching to a tendon or an aponeurosis Temporalis has both muscle attachment THE MOTOR UNIT Eacg muscle is served by at least one motor nerve MOVEMENT whuch contains hundreds of motor neuron axons I.) Movement along the axis or range of motion As a nerve enters a muscle it branches into a A. Nonaxial Movement number of axonal terminals, each of which forms a B. Uniaxial movement neuromuscular junction with a single nerve fiber. C. Biaxial movement A motor neuron and all the muscle fibers it D. Multiaxial movement supplies is called a motor unit. II.) Types of motion When a motor neurotransmits an electrical impulse A.) Gliding - one flat bone slides over another all the muscle fibers that it innervates respond by contracting The average number of muscle fibers oer unit is 150 but it ranges from 4 to several hundred Muscle that exert very fine control have a small motor units Large muscles of locomotion and weight bearing have large motor units as a consequence have less precise control MUSCULAR MOVEMENTS The muscle fibers in a unit are not clustered Flexion - bending mition in which angle between 2 together but rather are spread throughout the bones is decreased. entire muscle Extension - straightening motion in which angle Stimulation of a single unit causes a weak between 2 bones is increased. contraction of the entire muscle Hyperextension - extension beyond straight This allows control of the intensity of the position contraction Dorsiflexion - flexion of foot and ankle joint Palmar flexion - flexion of hand wrist SMOOTH MUSCLES Plantar flexion - extionsion of foot ankle Smooth muscle lacks courser connective tissue seen in skeletal muscle B.) ANGULAR MOVEMENT - increase or decrease the Small amounts is found betweel smooth muscle angle between 2 bones fibers 1. Flexion - bending motion that decrease the angle Smooth muscles are organized into sheets of of the joint bringing the 2 bones close together. closely apposed fibers These sheets occur in the walls of all but the smallest blood vessels and in the walls of hollow organs of the respiratory, urinary digestive and reproductive tracts In most cases, two sheets of muscles are present with their fibers aligned at right angle to each other. These forms the longitudinal (long axis) and circular (encircling) layer These two layers squeeze the contents of the organs 2. Extension - movement that increases the angle between 2 bones  3. Hypertension - bending the head backward D.) SPECIAL MOVEMENT 1. Supination - movement of the radius around the ulna. Palm faces up 2. Pronation - movement of the radius around the ulna. Palm faces down 4. Dorsiflexion (of the foot) - lifting the foot up so that it points to the shin Plantar (of the foot) - pointing the foot down 3. Inversion - sole of the foot turns medially 4. Eversion - sole of the foot turns laterally 5. Abduction - raising an arm laterally or spreading the fingers 6. Adduction - movement of the limb towards the 5. Protraction - nonangular anterior motiom along the body transverse plane. Jutting the jaw out 7. Circumduction - movement of a limb in a circle or 6. Retraction - nonangular posterior motion along the cone shape. transverse plane. Pulling the jaw back 7. Elevation - lifting a body parts superiorly. Shrugging shoulders closing the mouth 8. Depression - moving a body part inferiorly. C.) ROTATION Opening the mouth turning of the bone along its own long axis. Only the movement allowed between first 2 cervical vertebra  TYPES OF MUSCLE CONTRACTION Twitch ○ Momentary contraction of a muscle in response to a single stimulus such as electric current. Tetanus ○ If a muscle receives repeated stimuli at 9. Opposition - movement of the thumb in relation to a rapid rate, it cannot relax completely other digits between contractions ○ The tension achieved under such conditions is greater than the tension of a single muscle twitch and is called summation of twitches. A more or less continuous contraction of muscle is called tetanus Incomplete Tetanus ○ Occur when incomplete relaxation are still evident between contractions PHYSIOLOGY OF MUSCLE CONTRACTION Complete Tetanus Sliding - Filament model ○ Occurs when the muscle is in a steady Muscle tissue contracts when the 2 kinds of state of contraction with no relaxation at myofilaments slife past each other, increasing the all between stimuli as in “lockjaw” amount of overlap Treppe In maximally contracted muscle, the myosin ○ A type of contraction wherein a rested filaments are pulled inward the M line so that they muscle receives repeated stimuli over a actually overlap in the H zone prolonged period, the first few In partially contracted muscle, the myosin contractions increase in strength so that filaments of a sarcomere are separated by a the myogram starts out looking like an relatively small space in the H zone. upward staircase In relaxed muscle, the distance between myosin ISOTONIC AND ISOMETRIC CONTRACTION filaments in the H zone is relatively large. Thus the ISOTONIC length of the sarcomere can be seen to change Muscle contracts by becoming shorter and thicker with the degree of contraction. Tension remains constant as movement takes place Excitation - contraction coupling Example: Pulling a door The molecular basis for muscle contraction Powered by the hydrolysis of ATP ISOMETRIC A complete actin myofilaments is made up not only Muscles develop tension but remain the same of actin but also of the proteins, tropomyosin and length troponin. These are arranged in thin, twisted Example: Holding and open door strands. The myosin is composed of myosin molecules, which have oval-shaped “heads” and long “tails” Muscle Relaxation Acetylcholine is broken down by acetylcholinesterase. This breakdown prevents further stimulation of the muscle fibers by the motor neuron. Without the stimulation of an action potential, the Ca ions move aways from the myofilaments and are actively transported to tha sarcoplasmic reticulum by Ca-ATPase Without calcium, troponin and tropomyosin once again block the binding sites on the actin myofilaments, preventing myosin from forming cross bridges with actin As the myosin and Actin return to their original position, the I Band become broader and the Z lines move farther apart.