Download Skeletal Sys and Joints Overview

SKELETAL SYSTEM
Anatomy & Physiology
Functions
■ Support
■ Protection
■ Movement
■ Storage of minerals (Ca, P, etc.)
■ Hematopoiesis
– Spongy bone
How many?
■ Adult skeleton: 206 bones
■ Infant skeleton: 270
■ Axial skeleton: Skull and spine
■ Appendicular skeleton: Appendages
Shapes of bones
■ Long bone: rigid levers for muscle actions
– arm, leg, finger, toe)
■ Short bone: limited motion
– tarsal, carpal
■ Flat bone: thin sheets enclose organs
– sternum, skill, scapula
■ Irregular bone
– vertebrae, sphenoid, ethmoid
FUNCTIONAL UNIT
■ Haversian Canal- carry blood vessels
■ Lacunae- house the osteocyte
■ Canaliculi- transport nutrients
■ Osteocyte- mature bone cell
■ Volkmann- communication from outside to inside
■ Osteoblast- deposit new bone
– Calcitonin
■ Osteoclast- secret enzymes to dissolve bone
– create medullary cavity
– PTH
BONE FORMATION AND GROWTH
■ Ossification- conversion of cartilage to bone, controlled by hormones
■ Ossify from the center of diaphysis toward epiphyseal plate
■ Growth zone- where ossification occurs
■ Length of diaphysis until growth “epiphyseal plate” is ossified
BONE FORMATION AND GROWTH
■ Longitudinal- controlled by hormones, increase length
■ Appositional- increase in diameter
– Both occur in response to gravity and muscles on skeleton and changes in
calcium in blood
PHYSIOLOGY
■ Skeletal mass is replaced every 7 years
■ Majority of calcium is in teeth and skeleton
■ Calcium is used for:
– muscle contraction
– nerve impulse
– synapse s
– heart beat
– Secretions
– blood clotting
BONE MAINTENANCE AND REMODELING
■ Skeletons strongest in early adulthood
■ Osteoblast/clasts cancel each other out
■ Fetus: mostly cartilage, avascular
■ 3rd month of gestation: ossification of long bones
■ 16-25 years old- growth ends at epiphyseal plate
BONE MARROW
■ Blood cells and adipose
■ Spongy bone contains marrow
■ More yellow in adults
– Yellow marrow is found in shaft of bone
■ Red marrow is the site of hematopoiesis
– Children have more red marrow than adults
– Red marrow is found in ends of bones
FRACTURES
FRACTURES
■
Most common traumatic injury
■
Simple- closed, bone does not penetrate skin
■
Compound- open, bone penetrates skin
■
Comminuted- breaks into many fragments
■
Compression- bone crushed
■
Depressed- broken bone portion is pressed inward (skull)
■
Impacted- broken bone ends forced into each other
■
Spiral- excessive twisting forces (sports)
■
Greenstick- bone breaks incompletely (children)
■
Reduction- realignment of broken bone ends
BONE REPAIR
■ Hematoma formation- within hours, blood vessels and osteon die off
■ Splinting of break by fibrocartilage- days, dispose of waste and new capillaries form
■ Bony callus formation- weeks, joining of pieces
■ Bone remodel- months, shaping the bone, making it smooth
Connective tissue
■ Tendons connect muscle to bone across a joint, they are a specialized structure
– Muscle to bone
■ Ligament- binds bone together across a joint
– Bone to bone
■ Bursa- sacs to reduce friction
■ Cartilage
– Fibrocartilage
– Hyaline
ARTICULATIONS
■ Joints are between bones
■ They are classified by:
– Degree of movement
– Structure
■ Fibrous joint- immovable, skull/teeth sockets
■ Cartilaginous joint- slightly moveable, vertebrae
■ Synovial joint- freely moveable, ribs
Types of SYNOVIAL JOINTS
■ Gliding- flattened/slightly curved to produce a sliding motion (carpals)
■ Hinge- concave surface with convex surface, bends in one plane (knee, elbow,
phalanges)
■ Pivot- rotation around a central axis (neck)
■ Condyloid- biaxial movement (wrist)
■ Saddle- wide range of motions (thumb)
■ Ball and socket- move all plane/rotations (shoulder, hip)
GRAVITY
■ Stress prompts bones to add bone mas (density)
■ Gravity is a force and signal (allows the body to react), tells the muscles how strong
they need to be, muscle atrophy is when the body believes that the muscles are not
needed and you can lose up to 20% of mass→ 5% can vanish in a week!
■ Bone atrophy- 1% a month, could be a total of 40-60%, recovery is problematic---you
need to exercise a lot!
■ In space, you need machines to mimic gravity to combat this problem. There are
special chambers that do this
■ Weightlessness triggers inhibition of osteoblasts
CONDITIONS
■ Dislocation- bone displaced from joint, causes soft tissue damage
■ Subluxation- joint partially dislocated, corrects itself
■ Sprain- sudden/unusual motion, ligament can be torn
■ See disorder sheet & Powerpoint presentation for diseases
MOVEMENTS
■ Flexion- bringing two bones together
■ Extension- increasing angle between 2 bones (straightening)
■ Hyperextension- move past the normal range of extending
■ Abduction- move away from the midline
■ Adduction- move toward the midline
■ Circumduction- circular movement
■ Rotation
■ Opposition- touching thumb to tips of fingers
■ Pronation- forearm turns the hand
■ Depression-lower
■ Elevation-raise