health practices chapter 2

Chapter 2

The Skeletal System and its movements

Tissues and specialized functions

·      Muscle tissue- contract

·      Nervous tissue- generate/ conduct electrical messages

·      Epithelial tissue- close fitting cells to cover/line surfaces or form glands

·      Connective tissue- bind, support, insulate, and protect

o   Bone

·      Skeletal system

o   Bones

o   Related cartilages

o   Ligaments

o   Joints

Bone composition and structure

·      Extracellular matrix movement= calcium salts + collagen fibers

·      Compressive and tensile strength

o   Ability to resist pressure

Functions of bone

·      Support

o   Internal framework

·      Protection

o   Fragile structures/ organs (ex skull, ribcage, pelvis)

·      Movement

o   Act as levers for muscles

·      Blood cell production

o   Red bone marrow

·      Mineral storage

o   Calcium, phosphorus and magnesium

Types of bone

·      long bones- (limbs) tubular, longer than wide

·      short bones- cubical in shape (carpals and tarsals)

·      flat bones- thin and flat, often curved (skull)

·      irregular bones- not of the above categories, shape adapted for specific purpose (vertebrae)

·      sesamoid bones- form with a tendon to protect or change angle of the tendon (patella)

Typical long bone

·      Diaphysis- long center

o   Medullary cavity- hollow cavity of the diaphysis

·      Epiphysis- enlarged ends of the bone

o   Articular cartilage- covers the exterior of the epiphyses

o   Muscle attachment and bone articulation

·      Epiphyseal plate- “growth plate” in between the epiphysis and diaphysis

Bone growth and density

·      Closure of the epiphyseal plates occurs progressively from puberty to maturity

o   Between 15 and 25 years of age

o   Earlier in females than males

·      Bone density is greatly influenced by activity

o   Ballet dancers in the second metatarsal

Bone Density

·      Osteopenia- loss of bone density

·      Osteoporosis- increased porosity in bone (brittle bones)

·      Influenced by race, age, calcium, hormones, and gender

o   Estrogen is protective for bone density

o   Dancers low in estrogen or not menstruating (athletic amenorrhea) are at higher risk

o   Smokers at higher risk

o   Correlation to high caffeine and soft drink usage

Calcium intake

·      RDA 1200-1500mgs for young adults 11-24 years of age

·      3-4 servings of milk products per day

·      300mgs of calcium

o   8 ounces of milk

o   8 ounces of fortified OJ

o   1 cup collard greens

Stress Fractures

·      Microscopic crack that is so small, it is not even initially apparent on an X ray

o   70% of stress fractures in dancers happen between 15 to 19 years old

o   Later onset menstruation or irregular menstruation correlated/is a risk factor

Sprain vs Strain

·  Sprain – injury to a ligament

·  Strain – injury to the muscle

Human skeleton

·      206 bones in total

·      Axial

o   Skull

o   Vertebral column (spine)

o   Sternum

o   Ribs

Appendicular: limbs

Upper extremity

·  Shoulder girdle

o   Clavicles

o   Scapulae

·  Upper arm: humerus

·  Lower arm: radius - ulna

·   Hand: carpals (wrist), metacarpals (palm), phalanges (fingers)

Lower extremity

·  Pelvic girdle

o   Ilium (upper)

o   Ischium (lower)

o   Pubis (front)

·  Thigh: femur

·  Lower leg: tibia – fibula

·  Knee: patella

·  Foot: tarsals, metatarsals, phalanges

Joints

·      Articulation=connection between two adjacent bones or cartilage

2 functions

·      Bind skeleton together

·      Provide mobility

Classification of joint

·      Cartilaginous joints

o   United by cartilages

o   Intervertebral discs, pubic symphysis, and epiphyseal plates in long bones

Gliding (plane) joint

·      2 planes

·      Carpals

·      Tarsals

Hinge joint

·      1 plane

·      Elbow

·      Knee

Pivot joint

·      1 plane around own axis

·      Atlas and axis (neck)

·      Radius and ulna

Saddle joint

·      2 planes

·      Thumb (1^st carpometacarpal joint)

Condyloid joint

·      2 planes, not full rotation

·      Wrist (radiocarpal joint)

·      Fingers (knuckles)

Ball and socket joint

·      3 planes

·      Shoulder

·      Hip

Stability and mobility

·      Stability- ability of a joint to withstand forces without injury

·      Mobility- range of motion available

·      Flexibility- functional capacity of joints to move through a full range of motion

Joint Positions

·      Closed Packed

o   Articulating surfaces of synovial joints at greatest stability

§  ROM extreme

§  Joint surfaces with greatest contact area

§  Ligaments under tension

·      Loose packed

o   Greatest motion available

§  Surfaces have less contact

§  Ligaments slack