Grade 12 Kinesiology - 2.1 The Human Skeleton Theory

5 Types of Bones

1. Long Bones

2. Short Bones

3. Flat Bones

4. Irregular Bones

5. Sesamoid Bones

Long Bones + example(s)

any bone whose length greatly exceeds its diameter

provide wide range of motion (act as levers)

example: femur

Short Bones + example(s)

serve as shock absorbers + fine motor control

examples: carpals, tarsals

Femur

thigh bone

Carpals

bones of the wrist

Tarsals

bones of the ankle

Flat Bones + example(s)

are flat and thin

protect underlying organs

examples: skull, scapula, sternum, clavicle

Scapula

shoulder blade

Sternum

breastbone

Clavicle

collarbone

Irregular Bones + example(s)

bones that cannot be placed into any other category

fulfill a specific function

example: vertebrae

Vertebrae

bones that make up the spine

protect the spinal cord

Sesamoid Bones + example(s)

unusual, small bones

wrapped within tendons that move over bony surfaces

example: patella

Patella

kneecap

How many bones are in the adult body?

206 bones

How many bones in a baby?

300 bones

Fontanelle

soft spots on a newborn’s head where ossification has not been completed yet

Simple (closed) Fracture

fractures that stay within the body

Compound (open) Fracture

fractures that break through the skin

Simple Fracture

no separation of the bone

Compound Fracture

bone breaks in two

Comminuted Fracture

ends of broken bone are shattered into many small pieces

Stress Fracture

tiny cracks in bone caused by repeated activity

hardest to detect

Ossification Center

area where bone tissue forms (same as epiphyseal plates)

How many ossification centers are there in long bones vs short bones?

long bones: 3 ossification centers (one at each end and one in the center)

short bones: 1 ossification center

How is compact bone formed?

starts as cartilage

osteoblasts within the cartilage discharge osteoid

inorganic salts are deposited into the osteoid

osteoid hardens forming the compact bone

How is cancellous bone formed?

starts as fibrous membranes

osteoblasts release osteoid into the membrane

forms a sponge-like bundle of fibers

cancellous bone formation develops outwards from these centers in the membrane

Axial Skeleton

where most of the core muscles of the body originate from

protects major organs

consists of skull, ribs, sternum, vertebrae

How many bones make up the axial skeleton?

80 bones

Appendicular Skeleton

moveable bones

bones of the limbs

How many bones are in the appendicular skeleton?

126 bones

The upper limbs are connected to the ________ (shoulder) girdle, and the lower limbs are connected to the ______ (hip) girdle.

pectoral, pelvic

Articular Cartilage (AOLB)

at both ends of bone

allows for smooth movement while protecting the ends of the bones

True or False: Cartilage does have blood supply

False: Cartilage does not have blood supply

True or False: Blood supply is crucial to heal properly

True

Compact Bone (AOLB)

thick part of the bone

responsible for structural integrity

Cancellous (spongy) Bone (AOLB)

at ends of bone

filled with marrow

meant for shock absorption

Epiphysis (AOLB)

ends of bones

Diaphysis (AOLB)

shaft of bone

where the bone is thickest

Epiphyseal Plate (AOLB)

growth plates

where growth of the bone occurs (same as ossification centers)

Epiphyseal Line

occurs when epiphyseal plates have fused together after growth has stopped

How do (long) bones grow? How do we know they have stopped growing?

the epiphyseal plates at each end and in the center of the bones expand outwards until they meet each other, which forms the epiphyseal lines

we can know they’ve stopped growing if an x-ray is taken and you can see the epiphyseal lines

Periosteum

outer connective tissue that covers the entire length of the bone

connects to tendons/ligaments to connect muscle to bone or bone to bone respectively

Medullary Cavity

inside the diaphysis of the bone

filled with red marrow and yellow marrow

Red Marrow

found inside the medullary cavity

is where RBCs are produced

Yellow Marrow

found inside the medullary cavity

made up of adipose cells and connective tissue

Hematopoiesis

production of RBCs

Osteocytes

bone cells

Osteoblasts

bone forming cells (lay down osteoid)

Osteoclasts

bone-destroying cells

Ossfication

production of new bone

What % of total body weight comes from the skeletal system?

14%

4 Major Components of Bone

1. Calcium carbonate

2. Calcium phosphate

3. Collagen

4. Water

Osteoporosis

degenerative disease in which the holes in the cancellous part of the bone become too wide - the bone becomes brittle and easy to break

typically caused by low calcium intake and old age

4 Prevention Strategies for Osteoporosis

1. Eat a balanced diet (enough calcium and vitamin D)

2. Do weight training

3. Live a healthy lifestyle (no smoking or excessive alcohol)

4. Get regular bone density testing when necessary