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Bones, Joints and Muscles

Bones, Joints and Muscles. Bones: 206 in human body. Function: support (eg) pelvic bowl, legs protect (eg) skull, vertebrae mineral storage (eg) calcium, phosphate, inorganic component movement (eg) walk, grasp objects blood-cell formation (eg) red bone marrow

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Bones, Joints and Muscles

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  1. Bones, Joints and Muscles

  2. Bones: 206 in human body • Function: • support (eg) pelvic bowl, legs • protect (eg) skull, vertebrae • mineral storage (eg) calcium, phosphate, inorganic component • movement (eg) walk, grasp objects • blood-cell formation (eg) red bone marrow • Osteoblasts: secrete organic part of bone matrix = osteoid • Osteocytes:mature bone cells, maintain bone matrix

  3. Some Reminders about Bones • Bone = bone tissue (type of CT) • A Bone = an organ • Compact vs. Spongy Bone • Composition: Hydroxyapatite, protoplasm, collagen, blood vessels, marrow • Skeleton = bones, cartilage (avascular, no nerves, 80% H2O), joints, ligaments • Shapes of Bones • Long, Flat, Irregular, Short • Before 8 weeks, embryo is all cartilage

  4. Structure of Bone

  5. Anatomy of a Long Bone • Diaphysis • Medullary Cavity • Nutrient Art & Vein • 2 Epiphyses • Epiphyseal Plates • Epiphyseal Art & Vein • Periosteum • Outer: Dense irregular CT • Inner: Osteoblasts, osteoclasts • Does not cover epiphyses • Attaches to bone matrix via collagen fibers • Endosteum • Osteoblasts, osteoclasts • Covers trabeculae, lines medullary cavity

  6. 2 Types of Bone Formation • 1) Intramembranous Ossification • Membrane bones: most skull bones and clavicle • Osteoblasts in membrane secrete osteoid that mineralizes • Osteocytes maintain new bone tissue • Trabeculae forms between blood vessels • Grows into thickened plates at periphery = compact bone • Periosteum forms over it

  7. 2 Types of Bone Formation : • 2) Endochondral Ossification: All other bones • Begins with a cartilaginous model • Perichondrium becomes replaced by periosteum • Cartilage in diaphysis calcifies • Trabeculae forms from Periostealbud • Periosteal bud = arteries & veins, cells forming bone marrow, osteoblasts, osteoclasts • Medullary cavity is formed by action of osteoclasts • Epiphyses grow and eventually calcify • Epiphyseal plates remain cartilage for up to 20 years

  8. Bone Growth & Remodeling • GROWTH • Appositional Growth = widening of bone • Bone tissue added on surface by osteoblasts of periosteum • Medullary cavity maintained by osteoclasts • Lengthening of Bone • Epiphyseal plates enlarge by chondroblasts • Matrix calcifies (chondrocytes die and disintegrate) • Bone tissue replaces cartilage on diaphysis side • REMODELING • Due to mechanical stresses on bones, their tissue needs to be replaced • Osteoclasts-take up bone ( = breakdown) • release Ca2++ , PO4 to body fluids from bone • Osteoblasts-lay down bone • secrete osteoid to form new bone • Ideally osteoclasts and osteoblasts work at the same rate!

  9. Joints (articulations) • Where parts of skeleton meet • Allows varying amounts of mobility • Classified by structure or function • Arthrology: study of joints

  10. Classification of Joints • Function: • Synarthroses = no/little movement • Amphiarthroses = slight movement • Diarthroses = great movement

  11. Joints by Functional Classification

  12. Joint Classification • Structure • Cartilagenous • Synchondrosis: connected by hyaline cartilage (synarthroses) • Symphysis: connected by fibrocartilage (amphiarthroses) • Fibrous • Sutures: connected by short strands of dense CT (synarthroses) • Syndesmoses: connected by ligaments (varies) • Gomphosis: peg in socket w/short ligament (synarthroses) • Synovial (diarthroses)

  13. Joints by Structural Classification

  14. Components of SYNOVIAL JOINTS: (Structural Joint Classification continued) • Articular cartilage: hyaline; covers ends of both bones articulating • Synovial (joint) cavity: space holding synovial fluid • Articular capsule: Made of 2 layers • Fibrous: external, dense CT for strength • Synovial membrane: internal, produces synovial fluid • Synovial fluid: viscous; lubricates and nourishes; contained in capsule and articular cartilages • Reinforcing ligaments: extracapsular/intracapsular • Nerves + vessels: Highly innervated, Highly vascular • Meniscus (some): fibrocartilage; improves the fit of 2 bones to increase stability

  15. Synovial Joint pg 215

  16. Bursae & Tendon Sheaths • Bursae: flat, fibrous sac w/synovial membrane lining • Tendon Sheaths: elongated bursae that wraps around tendons • 3 Factors in Joint Stability: • Muscle Tone • Ligaments • Fit of Articular Surface pg 219

  17. pg 224 Joint Shapes • Hinge: cylindrical end of 1 bone fits into trough shape of other • angular movement-1 plane (eg) elbow, ankle, interphalangal • Plane: articular surface in flat plane • Short gliding movement • (eg) intertarsal, articular processes of vertebrae

  18. pg 225 Joint Shapes • Condyloid: egg-shape articular surface + oval concavity • side-to-side, back+forth movement • (eg) metacarpophalangeal (knuckle) • Pivot: round end fits into ring of bone + ligament • rotation on long axis • (eg) prox. radius/ulna, atlas/dens

  19. pg 225 Joint Shapes • Saddle: articular surface both concave + convex • side-to-side, back-forth movement • (eg) carpometacarpal jt of thumb • Ball + Socket: spherical head + round socket • multiaxial movement • (eg) shoulder, femur

  20. !Muscles! Function: 1) movement 2) maintain posture 3) joint stability 4) generate heat !Muscles!

  21. Special Features of Muscle • Contractibility= cells generate pulling force • Excitibility = nervous impulses travel through muscle plasma membrane to stimulate contraction • Extensibility = after contraction muscle can be stretched back to original length by opposing muscle action • Elasticity = after being stretched, muscle passively recoils to resume its resting length

  22. Muscle System: uses levers to move objects • How it works: A rigid bar moves on fixed point when a force is applied to it, to move object • Lever = rigid bar = bone • Fulcrum = fixed point = joint • Effort = force applied = muscle contraction • Load = object being moved = bone

  23. Movements of Muscles • Extension: increasing angle between body parts • Flexion: decreasing angle between body parts • Dorsiflexionvs.Plantarflexion • Inversionvs.Eversion • Abduction: moving away from the median plane • Adduction: moving towards the median plane • Rotation: moving around the long axis • Circumduction: moving around in circles

  24. Movements of Muscles • Elevation: lifting body part superiorly • Depression: moving body part inferiorly • Supination: rotating forearm laterally • Pronation: rotating forearm medially • Protraction: Anterior movement • Retraction: Posterior movement

  25. Muscle Basics to Remember • 3 Types: Skeletal, Cardiac, Smooth • Origin vs. Insertion • Direct vs. Indirect Attachments • direct = right onto bone • indirect = via tendon/aponeurosis • more common • leave bony markings = tubercle, crest, ridge, etc. • Sometimes attach to skin

  26. Functional Muscle Groups • Agonist = primary mover of a muscle, major response produces particular movement • (eg) biceps brachii is main flexor of forearm • Antagonists = oppose/reverse particular movement, prevent overshooting agonistic motion • (eg) triceps brachii is antagonist to biceps brachii

  27. Functional Muscle Groups • Synergists = muscles work together, adds extra force to agonistic movement, reduce undesirable extra movement • (eg) muscles crossing 2 joints • Fixators = a synergist that holds bone in place to provide stable base for movement • (eg) joint stablilizers

  28. Naming Muscles • Location: (eg) brachialis = arm • Shape: (eg) deltoid = triangle • Relative Size: (eg) minimus, maximus, longus • Direction of Fascicles: (eg) oblique, rectus • Location of Attachment: (eg) brachioradialis • Number of Origins: (eg) biceps, quadriceps • Action: (eg) flexor, adductor, extensor

  29. Arrangement of Muscle Fibers • Parallel: long axis of fascicles parallel to axis of muscle; straplike (eg) biceps, sternocleidomastoid • Convergent: O = broad, I = narrow, via tendon; fan or triangle shaped (eg) pectoralis major • Circular: fascicles arranged in concentric circles; sphincter (eg) around mouth

  30. Arrangement of Muscle Fibers • Pennate: fascicles short + attached obliquely to tendon running length of muscle; featherlike • Unipennate = fascicles insert on only 1 side • (eg) flexor pollicis longus • Bipennate = fascicles insert both sides • (eg) rectus femoris • Multipennate = many bundles inserting together • (eg) deltoid

  31. Arrangements of Muscle Fascicles pg 269

  32. STOP More on Levers on the following pages

  33. First Class Lever • Effort at 1 end • Load at other end • Fulcrum in middle • (eg) scissors • (eg) moving head up and down pg 267

  34. Second Class Lever • Effort at 1 end • Fulcrum at other end • Load in middle • (eg) wheelbarrel • (eg) standing on tip toes (not common in body) pg 267

  35. Third Class Lever • Load at 1 end • Fulcrum at other end • Force in middle • (eg) using a tweezers • (eg) lifting w/biceps pg 267

  36. Mechanical Advantage • When the load is close to the fulcrum, effort is applied far from fulcrum • Small effort over large distance = move large load over short distance • (eg) Using a jack on a car pg 266

  37. Mechanical Disadvantage • When the load is farther from the fulcrum than the effort, the effort applied must be greater than the load being moved • Load moved quickly over large distance • (eg) using a shovel pg 266

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