Skeletal system

206

bones in the human skeleton

organ

• bone is a complex living ___ made up of many cells, protein fibers, and minerals

• they come in many sizes and shapes

femur

largest bone

stapes

smallest bone

joints cartilages ligaments

the skeletal system also includes:

axial appendicular

two divisions of the skeleton

axial

Bones that form the longitudinal axis of the body make up the axial skeleton

Vertebral column

Bony thorax

skull

parts of the axial skeleton

vertebrae

sacrum

coccyx

part of vertebral column

sternum

ribs

bony thorax

cranium

facial bones

skull

vertebral column

Composed of 33 bones before birth; some later fuse to form 26 separate bones

7

amount of cervical vertebrae

12

amount of thoracic vertebrae

5

amount of lumbar vertebrae

5 fused

amount of saccrum

4 fused

amount of coccyx

cervical vertebrae

• 7 vertebrae located in the neck

• smallest and lightest vertebrae

atlas

C1

first vertebrae

axis

C2

second vertebrae

thoracic vertebrae

• 12 thoracic vertebrae

• Articulate with ribs

• Larger than cervical vertebrae

• Long spinous process that hooks sharply downward

Lumbar vertebrae

•5 lumbar vertebrae

•Much larger than other vertebrae to support the weight of the upper body

bony thorax

• 12 pairs of ribs articulate with the 12 thoracic vertebrae posteriorly

true ribs

• pairs 1-7

• articulate anteriorly directly to the sternum by cartilage

false ribs

• pairs 8-12

• articulate indirectly or not at all

floating ribs

last 2 pairs of false ribs that do not connect to false ribs

manubrium

body

xiphoid process

sternum parts

cranium

facial bones

the skull is formed by two sets of bones

mandible

all joints in skull are joined by immovable joints except for the ___

hyoid bone

• No direct articulation to another bone

• Provides attachment for these muscles:

  • Floor of mouth •Tongue

  • Larynx

  • Epiglottis

  • Pharynx

auditory ossicles

The smallest bones in the body are located in the middle ear:

• Malleus

• Incus

• Stapes

Malleus

Incus

Stapes

auditory ossicles

appendicular skeleton

Includes the limbs and the girdles which attach the limbs to the axial skeleton

appendicular skeleton

pectoral girdle: clavicle, scapula

upper limbs: humerus, ulna, radius, carpals, metacarpals, phalanges

pelvic girdle: ilium ischium, and pubis

lower limbs: femur, patella, tibia, fibula, tarsals, metatarsals, phalanges

pectoral girdle

clavicle

scapula

clavicle

aka collarbone

scapula

aka shoulder blade

humerus

upper arm

radius

lower arm; elbow to thumb side of the wrist

ulna

lower arm; elbow to pinkie side of the wrist

phalanges

metacarpals

carpals

bones of the hand

pelvic girdle

consists of two coxal or hip bones.

ilium

ischium

pubis

Each hip bone is formed from the fusion of 3 bones in pelvic girdle:

leg bones

femur

patella

tibia

fibula

femur

thigh bone

patella

kneecap

tibia

large bone in lower leg; sometimes called the shin bone

fibula

smaller bone in lower leg; forms the lateral ankle

coxal bones

sacrum

ilium

pubis

ischium

pubic symphysis

tarsals

metatarsals

phalanges

bones of the foot

long

short

flat

irregular

sesamoid

shapes of bones

compact bone spongy bone

two basic types of bone

compact bone

dense and looks smooth and homogeneous.

spongy bone

composed of small pieces of bone and lots of open space

compact bone

In long bones, surrounds spongy bone at ends

• Along shaft surrounding medullary cavity

spongy bone

At ends of long bones

spongy bone

• The open spaces keep bones light

compact bone

Composed of a matrix of hard mineral salts reinforced with tough collagen fibers

• osteocytes

• lacunae

osteocytes

Mature bone cells are called

lacunae

Osteocytes are found in tiny cavities within the matrix called

long bone

Diaphysis

Epiphysis

Articular Cartilages

Epiphyseal Line

Periosteum

diaphysis

• Shaft

• Composed of compact bone

Epiphysis

• End of the bone

• Composed mostly of spongy bone

Articular Cartilages

cover epiphyses for smooth movement

Epiphyseal Line

marking left from growth at epiphyseal plate

Periosteum

fibrous, connective tissue that covers the diaphysis

Red Marrow

in cavities of spongy bone in flat bones and epiphyses of long bones, site of hematopoiesis

Yellow Marrow

fat storage in medullary cavity

bone markings

Bumps, holes, and ridges where muscles, tendons, and ligaments are attached and where blood vessels and nerves pass through

categories of bone marking

projections or processes

depressions, cavities, or openings

example of bone markings

olecranon fossa

olecranon process

styloid process

joints

aka articulation

where two bones meet

hold bones together, but also gives mobility

ball and socket joints

most moveable joint

hip and shoulder

where ball and socket joints are

support

The skeleton provides an internal framework that supports and anchors all soft organs.

protection

Some bones protect soft body organs.

movement

•Skeletal muscles attach to bones by tendons

•Tendons use the bones as levers to move body parts

skeletal muscles

attach to bones by tendons

storage

•Fat storage in yellow marrow

•The minerals calcium and phosphorous are stored in bone tissue

hematopoiesis

Blood cell formation occurs in red marrow.

fontanels

•Spaces between bones of the skull in an infant

•Commonly called soft spots

•Fully ossified by 2 years

•Allows for growth of the brain and skull

Ossification

is the formation of bone from cartilage

• At birth, bones are part cartilage and part bone

2

The skeleton is fully ossified by age __ except for epiphyseal (growth) plates

longitudinal growth

• X-ray of 12-year-old showing epiphyseal (growth) plates at the distal ends of the tibia & fibula

• Epiphyseal plates are fully ossified by the end of adolescence

ossification

bone formation

epiphyseal plates

provide for longitudinal growth; increase in length

appositional growth

increase in diameter

osteoblasts

bone building cells

osteoclasts

bone-destroying cells

bone remodeling

• Breaking down & reforming of bone that occurs throughout life to maintain proportion & strength as well as healthy calcium levels

• Weakening of the bone that occurs with aging

• One in two women and one in four men over age 50 will have an osteoporosis-related fracture.

• ___ causes tissue loss as seen in the bottom image

• Top image shows healthy bone 59

Hip fracture

A ____ is actually a femoral fracture that occurs in the proximal end of the femur near the hip.

• The 1-year mortality rate after a hip fracture is over 30%

arthritis

inflammation of joints

osteoarthritis

usually part of aging

rheumatoid arthritis

autoimmune disease

rickets

• Lack of vitamin D, calcium, or phosphorus

• Bones fail to calcify; stay soft

• Usually in children ages 3-36 months

• Rare in developed countries

herniated disc

• Protruding discs of cartilage between the vertebrae

• Can irritate nearby nerves and result in pain, numbness or weakness in an arm or leg

scoliosis

•Abnormal curvature of the spine

•May be congenital or result from disease or trauma

spongy bone

• Found in the ends of long bones

spongy bone

• Also fills short bones, flat bones and some parts of irregular bones