Bones

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Bones

  1. 1. Bones, Joints and Muscles
  2. 2. Bones: 206 in human body <ul><li>Function: </li></ul><ul><ul><li>support (eg) pelvic bowl, legs </li></ul></ul><ul><ul><li>protect (eg) skull, vertebrae </li></ul></ul><ul><ul><li>mineral storage (eg) calcium, phosphate, inorganic component </li></ul></ul><ul><ul><li>movement (eg) walk, grasp objects </li></ul></ul><ul><ul><li>blood-cell formation (eg) red bone marrow </li></ul></ul><ul><li>Osteoblasts : secrete organic part of bone matrix = osteoid </li></ul><ul><li>Osteocytes: mature bone cells, maintain bone matrix </li></ul>
  3. 3. Some Reminders about Bones <ul><li>Bone = bone tissue (type of CT) </li></ul><ul><li>A Bone = an organ </li></ul><ul><li>Compact vs. Spongy Bone </li></ul><ul><li>Composition: Hydroxyapatite , protoplasm, collagen, blood vessels, marrow </li></ul><ul><li>Skeleton = bones, cartilage (avascular, no nerves, 80% H 2 O), joints, ligaments </li></ul><ul><li>Shapes of Bones </li></ul><ul><ul><li>Long, Flat, Irregular, Short </li></ul></ul><ul><li>Before 8 weeks, embryo is all cartilage </li></ul>
  4. 4. Structure of Bone
  5. 5. Anatomy of a Long Bone <ul><li>Diaphysis </li></ul><ul><ul><li>Medullary Cavity </li></ul></ul><ul><ul><li>Nutrient Art & Vein </li></ul></ul><ul><li>2 Epiphyses </li></ul><ul><ul><li>Epiphyseal Plates </li></ul></ul><ul><ul><li>Epiphyseal Art & Vein </li></ul></ul><ul><li>Periosteum </li></ul><ul><ul><li>Outer: Dense irregular CT </li></ul></ul><ul><ul><li>Inner: Osteoblasts, osteoclasts </li></ul></ul><ul><ul><li>Does not cover epiphyses </li></ul></ul><ul><ul><li>Attaches to bone matrix via collagen fibers </li></ul></ul><ul><li>Endosteum </li></ul><ul><ul><li>Osteoblasts, osteoclasts </li></ul></ul><ul><ul><li>Covers trabeculae, lines medullary cavity </li></ul></ul>
  6. 6. 2 Types of Bone Formation <ul><li>1) Intramembranous Ossification </li></ul><ul><ul><li>Membrane bones: most skull bones and clavicle </li></ul></ul><ul><ul><li>Osteoblasts in membrane secrete osteoid that mineralizes </li></ul></ul><ul><ul><li>Osteocytes maintain new bone tissue </li></ul></ul><ul><ul><li>Trabeculae forms between blood vessels </li></ul></ul><ul><ul><li>Grows into thickened plates at periphery = compact bone </li></ul></ul><ul><ul><li>Periosteum forms over it </li></ul></ul>
  7. 7. 2 Types of Bone Formation : <ul><li>2) Endochondral Ossification : All other bones </li></ul><ul><ul><li>Begins with a cartilaginous model </li></ul></ul><ul><ul><li>Perichondrium becomes replaced by periosteum </li></ul></ul><ul><ul><li>Cartilage in diaphysis calcifies </li></ul></ul><ul><ul><li>Trabeculae forms from Periosteal bud </li></ul></ul><ul><ul><ul><li>Periosteal bud = arteries & veins, cells forming bone marrow, osteoblasts, osteoclasts </li></ul></ul></ul><ul><ul><li>Medullary cavity is formed by action of osteoclasts </li></ul></ul><ul><ul><li>Epiphyses grow and eventually calcify </li></ul></ul><ul><ul><ul><li>Epiphyseal plates remain cartilage for up to 20 years </li></ul></ul></ul>
  8. 8. Bone Growth & Remodeling <ul><li>GROWTH </li></ul><ul><li>Appositional Growth = widening of bone </li></ul><ul><ul><li>Bone tissue added on surface by osteoblasts of periosteum </li></ul></ul><ul><ul><li>Medullary cavity maintained by osteoclasts </li></ul></ul><ul><li>Lengthening of Bone </li></ul><ul><ul><li>Epiphyseal plates enlarge by chondroblasts </li></ul></ul><ul><ul><li>Matrix calcifies (chondrocytes die and disintegrate) </li></ul></ul><ul><ul><li>Bone tissue replaces cartilage on diaphysis side </li></ul></ul><ul><li>REMODELING </li></ul><ul><li>Due to mechanical stresses on bones, their tissue needs to be replaced </li></ul><ul><ul><li>Osteoclasts -take up bone ( = breakdown) </li></ul></ul><ul><ul><ul><li>release Ca 2++ , PO 4 to body fluids from bone </li></ul></ul></ul><ul><ul><li>Osteoblasts -lay down bone </li></ul></ul><ul><ul><ul><li>secrete osteoid to form new bone </li></ul></ul></ul><ul><li>Ideally osteoclasts and osteoblasts work at the same rate! </li></ul>
  9. 9. Joints (articulations) <ul><li>Where parts of skeleton meet </li></ul><ul><li>Allows varying amounts of mobility </li></ul><ul><li>Classified by structure or function </li></ul><ul><li>Arthrology : study of joints </li></ul>
  10. 10. Classification of Joints <ul><li>Function: </li></ul><ul><ul><li>Synarthroses = no/little movement </li></ul></ul><ul><ul><li>Amphiarthroses = slight movement </li></ul></ul><ul><ul><li>Diarthroses = great movement </li></ul></ul>
  11. 11. Joints by Functional Classification Glenohumeral joint Knee joint TMJ Great Diarthrosis Distal Tibia/fibula Intervertebral discs Pubic symphysis Slight Amphiarthrosis Sutures, Teeth, Epiphyseal plates, 1 st rib and costal cart. None (minimal) Synarthrosis Example Movement Type
  12. 12. Joint Classification <ul><li>Structure </li></ul><ul><ul><li>Cartilagenous </li></ul></ul><ul><ul><ul><li>Synchondrosis : connected by hyaline cartilage (synarthroses) </li></ul></ul></ul><ul><ul><ul><li>Symphysis : connected by fibrocartilage (amphiarthroses) </li></ul></ul></ul><ul><ul><li>Fibrous </li></ul></ul><ul><ul><ul><li>Sutures : connected by short strands of dense CT (synarthroses) </li></ul></ul></ul><ul><ul><ul><li>Syndesmoses : connected by ligaments (varies) </li></ul></ul></ul><ul><ul><ul><li>Gomphosis : peg in socket w/short ligament (synarthroses) </li></ul></ul></ul><ul><ul><li>Synovial (diarthroses) </li></ul></ul>
  13. 13. Joints by Structural Classification Glenohumeral joint Knee joint TMJ Synovial Skull Distal Tibia/fibula Teeth in sockets Sutures Syndesmoses Gomphosis Fibrous Epiphyseal plates Intervertebral discs Synchondrosis Symphysis Cartilagenous Example Type Structure
  14. 14. Components of SYNOVIAL JOINTS: ( Structural Joint Classification continued) <ul><li>Articular cartilage : hyaline; covers ends of both bones articulating </li></ul><ul><li>Synovial (joint) cavity : space holding synovial fluid </li></ul><ul><li>Articular capsule: Made of 2 layers </li></ul><ul><ul><li>Fibrous: external, dense CT for strength </li></ul></ul><ul><ul><li>Synovial membrane: internal, produces synovial fluid </li></ul></ul><ul><li>Synovial fluid : viscous; lubricates and nourishes; contained in capsule and articular cartilages </li></ul><ul><li>Reinforcing ligaments: extracapsular/intracapsular </li></ul><ul><li>Nerves + vessels : Highly innervated, Highly vascular </li></ul><ul><li>Meniscus (some): fibrocartilage; improves the fit of 2 bones to increase stability </li></ul>
  15. 15. Synovial Joint pg 215
  16. 16. Bursae & Tendon Sheaths <ul><li>Bursae : flat, fibrous sac w/synovial membrane lining </li></ul><ul><li>Tendon Sheaths: elongated bursae that wraps around tendons </li></ul><ul><li>3 Factors in Joint Stability: </li></ul><ul><ul><li>Muscle Tone </li></ul></ul><ul><ul><li>Ligaments </li></ul></ul><ul><ul><li>Fit of Articular Surface </li></ul></ul>pg 219
  17. 17. Joint Shapes <ul><li>Hinge: cylindrical end of 1 bone fits into trough shape of other </li></ul><ul><ul><li>angular movement-1 plane (eg) elbow, ankle, interphalangal </li></ul></ul><ul><li>Plane : articular surface in flat plane </li></ul><ul><ul><li>Short gliding movement </li></ul></ul><ul><ul><li>(eg) intertarsal, articular processes of vertebrae </li></ul></ul>pg 224
  18. 18. Joint Shapes <ul><li>Condyloid : egg-shape articular surface + oval concavity </li></ul><ul><ul><li>side-to-side, back+forth movement </li></ul></ul><ul><ul><li>(eg) metacarpophalangeal (knuckle) </li></ul></ul><ul><li>Pivot : round end fits into ring of bone + ligament </li></ul><ul><ul><li>rotation on long axis </li></ul></ul><ul><ul><li>(eg) prox. radius/ulna, atlas/dens </li></ul></ul>pg 225
  19. 19. Joint Shapes <ul><li>Saddle : articular surface both concave + convex </li></ul><ul><ul><li>side-to-side, back-forth movement </li></ul></ul><ul><ul><li>(eg) carpometacarpal jt of thumb </li></ul></ul><ul><li>Ball + Socket : spherical head + round socket </li></ul><ul><ul><li>multiaxial movement </li></ul></ul><ul><ul><li>(eg) shoulder, femur </li></ul></ul>pg 225
  20. 20. !Muscles! Function: 1) movement 2) maintain posture 3) joint stability 4) generate heat !Muscles!
  21. 21. Special Features of Muscle <ul><li>Contractibility = cells generate pulling force </li></ul><ul><li>Excitibility = nervous impulses travel through muscle plasma membrane to stimulate contraction </li></ul><ul><li>Extensibility = after contraction muscle can be stretched back to original length by opposing muscle action </li></ul><ul><li>Elasticity = after being stretched, muscle passively recoils to resume its resting length </li></ul>
  22. 22. Muscle System: uses levers to move objects <ul><li>How it works: A rigid bar moves on fixed point when a force is applied to it, to move object </li></ul><ul><li>Lever = rigid bar = bone </li></ul><ul><li>Fulcrum = fixed point = joint </li></ul><ul><li>Effort = force applied = muscle contraction </li></ul><ul><li>Load = object being moved = bone </li></ul>
  23. 23. Movements of Muscles <ul><li>Extension: increasing angle between body parts </li></ul><ul><li>Flexion: decreasing angle between body parts </li></ul><ul><ul><li>Dorsiflexion vs. Plantarflexion </li></ul></ul><ul><ul><li>Inversion vs. Eversion </li></ul></ul><ul><li>Ab duction: moving away from the median plane </li></ul><ul><li>Ad duction: moving towards the median plane </li></ul><ul><li>Rotation : moving around the long axis </li></ul><ul><li>Circumduction : moving around in circles </li></ul>
  24. 24. <ul><li>Elevation : lifting body part superiorly </li></ul><ul><li>Depression : moving body part inferiorly </li></ul><ul><li>Supination: rotating forearm laterally </li></ul><ul><li>Pronation: rotating forearm medially </li></ul><ul><li>Protraction : Anterior movement </li></ul><ul><li>Retraction : Posterior movement </li></ul>Movements of Muscles
  25. 25. Muscle Basics to Remember <ul><li>3 Types: Skeletal, Cardiac, Smooth </li></ul><ul><li>Origin vs. Insertion </li></ul><ul><li>Direct vs. Indirect Attachments </li></ul><ul><ul><li>direct = right onto bone </li></ul></ul><ul><ul><li>indirect = via tendon/aponeurosis </li></ul></ul><ul><ul><ul><li>more common </li></ul></ul></ul><ul><ul><ul><li>leave bony markings = tubercle, crest, ridge, etc. </li></ul></ul></ul><ul><ul><ul><li>Sometimes attach to skin </li></ul></ul></ul>
  26. 26. Functional Muscle Groups <ul><li>Agonist = primary mover of a muscle, major response produces particular movement </li></ul><ul><ul><li>(eg) biceps brachii is main flexor of forearm </li></ul></ul><ul><li>Antagonists = oppose/reverse particular movement, prevent overshooting agonistic motion </li></ul><ul><ul><li>(eg) triceps brachii is antagonist to biceps brachii </li></ul></ul>
  27. 27. Functional Muscle Groups <ul><li>Synergists = muscles work together, adds extra force to agonistic movement, reduce undesirable extra movement </li></ul><ul><ul><li>(eg) muscles crossing 2 joints </li></ul></ul><ul><li>Fixators = a synergist that holds bone in place to provide stable base for movement </li></ul><ul><ul><li>(eg) joint stablilizers </li></ul></ul>
  28. 28. Naming Muscles <ul><li>Location: (eg) brachi alis = arm </li></ul><ul><li>Shape: (eg) deltoid = triangle </li></ul><ul><li>Relative Size: (eg) minimus, maximus, longus </li></ul><ul><li>Direction of Fascicles: (eg) oblique, rectus </li></ul><ul><li>Location of Attachment: (eg) brachioradialis </li></ul><ul><li>Number of Origins: (eg) biceps, quadriceps </li></ul><ul><li>Action: (eg) flexor, adductor, extensor </li></ul>
  29. 29. Arrangement of Muscle Fibers <ul><li>Parallel: long axis of fascicles parallel to axis of muscle; straplike (eg) biceps, sternocleidomastoid </li></ul><ul><li>Convergent : O = broad, I = narrow, via tendon; fan or triangle shaped (eg) pectoralis major </li></ul><ul><li>Circular : fascicles arranged in concentric circles; sphincter (eg) around mouth </li></ul>
  30. 30. Arrangement of Muscle Fibers <ul><li>Pennate : fascicles short + attached obliquely to tendon running length of muscle; featherlike </li></ul><ul><ul><li>Unipennate = fascicles insert on only 1 side </li></ul></ul><ul><ul><ul><li>(eg) flexor pollicis longus </li></ul></ul></ul><ul><ul><li>Bipennate = fascicles insert both sides </li></ul></ul><ul><ul><ul><li>(eg) rectus femoris </li></ul></ul></ul><ul><ul><li>Multipennate = many bundles inserting together </li></ul></ul><ul><ul><ul><li>(eg) deltoid </li></ul></ul></ul>
  31. 31. Arrangements of Muscle Fascicles pg 269
  32. 32. STOP More on Levers on the following pages
  33. 33. First Class Lever <ul><li>Effort at 1 end </li></ul><ul><li>Load at other end </li></ul><ul><li>Fulcrum in middle </li></ul><ul><li>(eg) scissors </li></ul><ul><li>(eg) moving head up and down </li></ul>pg 267
  34. 34. Second Class Lever <ul><li>Effort at 1 end </li></ul><ul><li>Fulcrum at other end </li></ul><ul><li>Load in middle </li></ul><ul><li>(eg) wheelbarrel </li></ul><ul><li>(eg) standing on tip toes (not common in body) </li></ul>pg 267
  35. 35. Third Class Lever <ul><li>Load at 1 end </li></ul><ul><li>Fulcrum at other end </li></ul><ul><li>Force in middle </li></ul><ul><li>(eg) using a tweezers </li></ul><ul><li>(eg) lifting w/biceps </li></ul>pg 267
  36. 36. Mechanical Advantage <ul><li>When the load is close to the fulcrum, effort is applied far from fulcrum </li></ul><ul><li>Small effort over large distance = move large load over short distance </li></ul><ul><li>(eg) Using a jack on a car </li></ul>pg 266
  37. 37. Mechanical Disadvantage <ul><li>When the load is farther from the fulcrum than the effort, the effort applied must be greater than the load being moved </li></ul><ul><li>Load moved quickly over large distance </li></ul><ul><li>(eg) using a shovel </li></ul>pg 266

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