Anatomy and Physiology: Chapter 5 The Skeletal System

includes bones, joints, cartilage, and ligaments

• adapted for movement and protection

• 2 divisions

skeletal system

2 divisions of skeletal system

axial, appendicular

bones that form longitudinal axis of body

• skull, vertebrae, chest

axial skeleton

bone soft limbs and girdles (attachment points)

appendicular skeleton 

5 functions of bones

1. support

2. protection

3. movement

4. storage

5. blood cell formation

explain support

form internal framework, cradles organs

explain protection

protects soft body organs, brain, spinal cord

explain movement

bones act as levers to move body

explain storage 

fat, minerals (calcium, phosphorous)

explain blood cell formation

hematopoiesis, occurs in certain bones

how many bones does a human have

206

how are bones classified 

type and shape 

2 types of bones

compact and spongy

dense and rigid, looks smooth, forms outer shell of most bones

compact bone

small needle-like pieces, open spaces( inside of bones) 

• cells inside if holes 

spongy bone 

3 shapes of bones

1. long

2. short

3. flat

longer than they are wide, mostly compact bone

• all bones of limbs except patella, wrist, and ankle

long bones

generally cube shaped, mostly spongy bone 

• bones of wrist and ankles 

short bones 

small short bone embedded with a tendon

• patella

sesamoids

thin, flattened, usually curved, two thin layers of compact bone around spongy bone

• skull, ribs, sternum

flat bones

do not fit into any other category 

• vertebrae, hip bones, most facial bones 

irregular bones 

anatomy of long bones

• diaphysis

• epiphyses

• epiphyseal plate

makes up the long part of a bone

diaphysis

ends of long bone 

• thin layer of compact bone enclosing area of spongy bone 

epiphyses 

flat plate of hyaline cartilage, cause the lengthwise growth of long bones, seen in young growing bones

• epiphyseal line in adult bones, remnants of epiphyseal plate in adults

epiphysial plate

dense layer of connective tissue covering bones

periosteum

perisoteum 

• attached by hundreds of _____

• anchors ____ ____ to bone

• found everywhere except _____

fibers, blood vessels, ends of bones

type of hyaline cartilage covering the ends of long bones and where two bones meet on other types

articular cartilage

articular cartilage decreases _____ at joint surfaces

friction

cavity inside bone, houses, bone marrow

medullary cavity 

storage area for fat in cavity of long bones of adults

yellow bone marrow

site of blood cell formation in infants

red bone marrow

where is red bone marrow found in adults

vertebrae, hips, breastbone, skull, and ends of long bones in arms and legs

marks, bumps, holes, or ridges on surfaces of bone that indicate where muscles, tendons, and ligaments attach and where blood vessels and nerves pass 

bone markings 

grow out from bone surface, site of muscle and ligament attachments, help form joints

projections

indentations in bone, allow passage of blood vessels, and nerves

depression and cavities

mature living bone cells 

osteocytes 

tiny cavities that house osteocytes

lacunae

arrangement of lacunae concentric circles

lamella

carries blood vessels and nerves to all areas of bone 

• top to bottom 

haversian (centra) canal 

each complex consisting of central canal and matrix of rings

osteon or Haversian system

tiny canals that radiate outward from the central canal to all lacunae

• connects all bone cells to nutrient supply through the bone matrix

canaliculi

small channels that transmit blood vessels from periosteum into the bone, connect central canals

• left to right

perforating (Volkmann’s) canals

what is skeleton made from

bone and cartilage

embryo skeletons are primarily

cartilage

most cartilage is replaced by ___ at birth except what 4 things 

bone, part of nose, most joints, growth plates, ears 

babies are born with how many bones

300

the process of bone formation

• involves 2 types of cells

ossification

2 types of cells involved in ossification

osteoblasts, osteoclasts

bone forming cells

osteoblasts

bone destroying cells

osteoclasts

4 steps of bone formation 

1. formation of bone collar and internal bone cavity 

2. blood vessels form

3. medullary cavity 

4. ossification of epiphysis 

explain step 1 of bone formation

• bone forms around hyaline cartilage

• cartilage replaced by bone to make internal cavity

• carried out by osteoblasts and osteoclasts

explain step 2 of bone formation

blood vessels go into the cell

explain step 3 of bone formation 

medullary cavity is carved out by osteoclasts 

explain step 4 of bone formation

ends of bones form

bone growth occurs in ___ and ___

length, width

bone growth is controlled by ___ 

hormones 

osteoblasts add bone tissue to

external face of bone

osteoclasts remove bone from

inner face

lifelong process, mature bone tissue is removed and new bone tissue is added 

bone remodeling 

bone remodeling is controlled by what two mechanisms

calcium levels and pull of gravity

if your blood calcium levels drop then

osteoclasts break down bone ad release calcium into the blood

if calcium levels are to high then

calcium deposited into bone

pull of gravity 

• bones become ____ in ____ muscle areas

• muscles _____  _____ to pull on muscles

• bones become _____

• physically inactive areas lose ______ _____

thicker, bulky, work harder, stronger, bone mass

broken bone does not penetrate skin

closed (simple) fracture

broken bone ends penetrate skin 

compound (open) fracture 

compound fractures affect ______, ____, and _____

high risk for _____

skin, muscle, other tissue, infection

bone breaks into many fragments

• common in elderly and people with brittle bones

comminuted fracture

bone is weakened and crushed by other bone 

compression fracture

broken bone fragment pushed inward

• skull fracture

depressed fracture

broken bone ends are forced into each other 

• common in falls

impacted fracture

ragged break occurs from excessive twisting 

spiral fracture

bone breaks incompletely (not all the way)

• common in children because of flexible bones

• bones bend or buckle

greenstick fracture

bone breaks in a straight line across the bone 

transverse fracture 

treatment for a fracture, realignment of bones

reduction

bone ends are put back in normal position outside of the body 

closed reduction 

bone ends are put back in normal position by surgery 

open reduction 

healing time for simple fracture

6-8 weeks

healing time is longer for

larger bones, elderly, and surgery

4 steps of bone repair processes

1. formation of hematoma

2. fibrocartilage callus

3. bony callus forms

4. bone remodeling occurs

what happens in first step of bone repair process

Formation of hematoma

• blood vessels rupture causing a hematoma

• bone cells deprived of nutrition die

explain step 2 of repair process

Fibrocartilage callus

• new blood vessels grow

• disposal of dead tissue fibrocartilage is formed

explain step 3 of bone repair process

Bony callus formed

• osteoblasts and osteoclasts migrate towards injured area

• bony callus formed

explain step 4 of bone repair process

Bone remodeling occurs 

• bony callus is remodeled

• strong permanent patch is formed at injured site

blood filled swelling 

hematoma 

what is fibrocartilage made of

cartilage, bone, and protein fibers

what is a bony callus made of

spongy bone

skull is formed by how many sets of bone

2

what are the 2 sets of bones that form skull

cranium and facial bones

encloses and protects brain tissue 

cranium 

hold the eyes, allow facial muscles to move

facial bones

all bones of skull are interlocked together by ______ except for ______

sutures, jawbone

what type of bones are the following 

• frontal bone

• parietal bone

• temporal bone

• occipital bone 

• sphenoid

• ethmoid

cranium bones 

forms forehead, bony projections under eyebrows, superior part of each eye

1 bone

frontal bone

paired bones, form most of superior and lateral walls of cranium

2 bones

parietal bone

inferior to parietal bones, several bone markings 

2 bones

temporal bones 

3 bone markings for temporal bones

• ear canals

• cheek bones

• air cavities

most posterior, forms floor and back wall of skull

1 bone

occipital bone