skeletal system

Question 1

define the skeletal system

Answer 1

consists of bones, cartilage and ligaments tightly joined to form a strong, flexible framework for the body

Question 2

describe osteology

Answer 2

skeleton
bone is living tissue
newborn human has 350 bones
adult human has 206 bones

Question 3

what are the functions of the skeletal system I

Answer 3

support for body and framework for attachment of soft tissues and organs

movement = attachment of skeletal muscles to bones either side of joints enable movement

protection = many soft tissues and organs surrounded by bone for protection

Question 4

functions of skeletal system II

Answer 4

storage of minerals = calcium salts, important for maintaining normal conc of calcium and phosphate ions in body fluids
storage of lipids in areas filled with yellow marrow are important for energy reserves
blood cell production = red and wbc and other blood elements are produced in red marrow

Question 5

describe bone formation and growth

Answer 5

ossification = formation of bone and replacing other tissues with bone

two forms:
endochrondral = bone replaces existing cartilage model

intramembranous = bone develops directly from mesenchyme or fibrous connective tissue

Question 6

describe endochondral ossification

Answer 6

bone originates as a cartilage model
cartilage is flexible connective tissue found in many areas of body
chondrocytes are only cells found in healthy cartilage

produce and maintain cartilaginous matrix, which consists mainly of collagen

Question 7

stage 1 of endochondral ossification

Answer 7

chondrocytes begin to increase in size while matrix calcifies around them

chondrocytes become starved then die

Question 8

stage 2 of endochondral ossification

Answer 8

blood vessels grow into perichondrium

cells in perichondrium differentiate into osteoblasts and begin forming bone around edge of cartilage shaft
now termed = periosteum

Question 9

stage 3 endochondral ossification

Answer 9

blood vessels and fibroblasts migrate to cartilage. fibroblasts differentiate into osteoblasts

calcified cartilage matrix breaks down and replaced by trabecular bone

site where this first occurs known as primary ossification centre

Question 10

stage 4 endochondral ossification

Answer 10

wave of ossification spreads towards ends of long bone

osteoclasts absorb bone from centre leaving a marrow cavity

bone grows inwards from periosteum forming compact bone surrounding marrow cavity

Question 11

stage 5 endochondral ossification

Answer 11

capillaries and osteoblasts migrate into epiphyses and ossification begins
these areas aka secondary ossification centres

timing of appearance of secondary ossification centre varies greatly

Question 12

describe immature long bone

Answer 12

formation of trabecular bone in epiphysis leaves two areas of cartilage

articular cartilage = articulates with cartilage from another bone, prevents bone articulations

epiphyseal growth plate = allows interstitial growth in bone

Question 13

growth of cartilage

Answer 13

interstitial growth = growth within epiphyseal growth plate

apposition growth = new layers of cartilage added to surface e.g. perichondrium

Question 14

describe factors that affect bone development I

Answer 14

organic and mineral components of bone matrix are being recycled and renewed through process of remodelling

normal bone growth and maintenance depend on combination of environmental, nutritional and hormonal factors

Question 15

factors that affect bone development II

Answer 15

overall shape and dimensions determined genetically
bone adapts to meet functional demands

availability of calcium, phosphate salts, vitamin ACDK and B12 essential for normal bone development

Question 16

factors affecting bone development III

Answer 16

several hormones including calcitonin, parathyroid hormone, growth hormone and sex hormone can affect calcium levels and bone growth

disease processes e.g. infection, bone tumours and tuberculosis can affect bone growth

loss of calcium and ability to use it causes brittle bones which easily fracture

Question 17

what are the 2 divisions of skeleton

Answer 17

axial

appendicular

Question 18

describe axial skeleton

Answer 18

forms central supporting axis of body 
skull
vertebral column
ribs 
sternum

Question 19

describe appendicular skeleton

Answer 19

bones of upper limb and pectoral girdle

bones of lower limb and pelvic girdles

Question 20

describe long bones

Answer 20

elongated tubular shafts, central medullary cavity and expanded ends for articulation

femur, humerus and tibia

Question 21

describe short bones

Answer 21

constructed of thin outer shell of compact bone with interior completely occupied by cancellous bone

carpus and tarsus

Question 22

describe flat bones

Answer 22

bones of vault of skull, consist of two shells of compact bone separated by layer of cancellous bone

Question 23

describe irregular bones

Answer 23

anything that will not fit into other categories

Question 24

sesamoid bones

Answer 24

formed in tendon

Question 25

what are the curvatures of vertebral column

Answer 25

vertebral column = 4 curves

1. cervical curvature
2. thoracic curvature
3. lumbar curvature
4. sacral curve

produces s shaped spine compared with c shaped spine present at birth = allows for bipedal walking by ensuring head is balanced over bodies centre of gravity

Question 26

describe scoliosis

Answer 26

abnormal lateral curvature
most common deformity
occurs mainly in thoracic region
may be developmental, which body and arch of vertebrae fail to develop on one side

can be corrected with back brace if detected early enough

Question 27

how many bones in skull

Answer 27

22
8 cranial
14 facial

6 auditory ossicles

Question 28

describe cranial structures and fontanelles in foetal skull

Answer 28

anterior fontanelle closes on average between 13 and 24 months
posterior between 6-8 weeks after birth

Question 29

describe ribs

Answer 29

12 pairs of ribs

1-7 = true ribs 
8-12 = false ribs 

ribs described as typical (3-10) or atypical (1,2,11 and 12)

Question 30

describe appendicular skeleton = pectoral girdle

Answer 30

supports upper limb and connects to axial skeleton

Question 31

appendicular skeleton - upper limb

Answer 31

divided into 3 segments, containing total of 30 bones
arm proper = contain humerus

forearm = contains radius and ulna

hand = contains 8 carpal bones in hand, 5 metacarpals in palm and 14 phalanges in digits

Question 32

appendicular skeleton = pelvic girdle

Answer 32

supports lower limb and connects to axial skeleton

consists of hip bones on each side and sacrum and coccyx

Question 33

appendicular skeleton = lower limb

Answer 33

divided into 3 segments, containing total of 30 bones

femoral = femur and patella 
crural = tibia and fibula 
foot = 7 tarsal bones, 5 metatarsals, 14 phalanges in toes

Question 34

classification of joints

Answer 34

synarthrosis = fixed

amphiarthosis = slightly moveable

diarthrosis = freely moveable

structural:
fibrous
cartilaginous
synovial

Question 35

describe synovial joints I

Answer 35

majority of joints in body = freely moveable

fibrous capsule and synovial membrane collectively known as articular capsule

Question 36

describe synovial joints II

Answer 36

hinge = elbow, fingers
ball and socket = shoulder, hip
pivot= neck, radiohumeral 
saddle = thumb, carpometacarpal 
gliding = carpals 
condylar = map joints