Chapter 6 Study Guide:
Skeletal Cartilage (3 Types):
1) Hyaline- “frosted glass.” Most Abundant, spherical chondrocytes (See
page 135, fig. 4 g- Note there are no visible fibers. Matrix is collagen
fibers only.
a) Articular cart.- located on ends of bones at movable joints
b) Costal Cart.- ribs to sternum “breastbone”
c) Respiratory cart.-forms voice box and other respiratory passages
d) Nasal cart.- supports external nose
2) Elastic- has more stretchy fibers and can stand up to repeated
bending. (See page 136 figure 4 h. Note the FIBERS.)
a) External ear
b) Epiglottis
3) Fibrocartilage- strong and flexible (perfect intermediate between
hyaline and elastic) Withstands heavy pressure. (See page 136 4i).
Note fibers form parallel rows, alternating chondrocytes with thick
collagen fibers.
a) Vertebrae
b) Knee joint
(See diagram page 177 for major areas of cartilage in adult skeleton.)
Growth of Cartilage:
 Ends during adolescence. Calcium may deposit during youth and old age.
Note: Calcified cartilage does not equal bone.
1) Appositional growth- “ growth from outside”
2) Interstitial growth- “growth from inside” from lacunae bound
chondrocytes dividing and secreting matrix.
THE BONES
Classification of bones (206 bones total)
I.
II.
Axial skeleton- long axis of body (Includes skull, vertebral
column, rib cage). Function: support, protection, carry other
parts
Appendicular- upper and lower limbs. (Shoulder blades and
hip bones aka girdles)
Function: Locomotion and manipulate
Four Bone Classes wrt Shape
1) Long bones- longer than wide, shaft and 2 ends.
a) Consist of all limb bones except patella, wrist, and ankles. Includes
the finger bones.
2) Short bones- cube shaped.
a) Sesamoid bones- form in a tendon (i.e. Patella)
b) Wrist and ankle bones
3) Flat bones- thin, flat, slightly curved (i.e. Sternum, scapulae, ribs,
skull bones)
4) Irregular bones- fit none of above classes (i.e. Vertebrae and hip
bones)
Functions of Bones (5)
1)
2)
3)
4)
5)
Support-provides framework
Protection- skull, vertebrae, rib cage
Movement- skeletal muscles attach by tendons, use bones as levers
Mineral storage- calcium and phosphate
Blood cell formation “hematopoisis” occurs in marrow of certain
bones
Bones Are Organs because composed of more than one tissue type.
Bone Structure:
Gross Anatomy- See table 6.1
for markings of bones
A: Compact bone- external layer
B. Spongy bone- (trabeculae are struts or thin plate inside bone)
Contain red or yellow marrow
Structure of typical Long Bone:
1)Diaphysus- tubular shaft forms a long axis, also contains a thick collar,
medullary “marrow” cavity (adults have yellow marrow)
2)Epiphyses- bone ends, covered with hyaline cartilage
Between them is the epiphyseal plate- a disc of hyaline cartilage where
growth occurs (line is called metaphysis)
3)Membranes- periosteum- double membrane covers remainder of
bone(not at the joints)
a) inner layer- osteogenic
b) fibrous layer- dense irregular connective
2 bone cells:
1. Osteoblast- bone makers
2. Osteoclast- bone breakers
Nutrient foramen – opening where blood vessels, nerves, lymphatic
vessels
2 protective layers for bones:
Periostem is attached to the bone by perforating (sharpey’s) fiberscollagen fibers
Endosteum- internal bone covered by
Structure of Short, Irregular, and Flat Bones
No marrow cavity but contain marrow between trabeculae
Spongy bone is called diploe
Red marrow cavitiesYellow marrow may convert to red marrow if a person becomes anemic.
MicroscopicCompact bone1) structural unit is called osteon or Haversian system provides
support. Central canal contains vessels and nerve fibers.
2) Perforating or Volkmann’s canals- lie at right angles to osteon
Spongy bone- no osteons present, nutrients by diffusion
Chemical Composition of Bone1) Organic component- cells ( osteoblast, osteoclast, osteocytes) and
osteoid- organic part of the matrix, 1/3 of matrix
2) Inorganic- mineral salts “hydroxyapatites” mostly calcium
phosphates
Bone Development:
1). Ossification and Osteogenesis: Formation of the boney
skeleton.
2). Endochondral Bone: Hyaline Cartilage is replaced by
bone. Begins in 8 weeks.
3). Intramembranes Ossification: Results in the formation of
the cranial bones and the skull formation, Flat bones, and
Ossification of the mesenchymal cells. Begins in 8 weeks.
Postnatal Bone Growth:
1). Longitudinal Bone Growth: Mimics Endochondral Bones.
2). Growth In Width: Appositional Growth-.
3). Hormonal Regulation Of Bone:
Bone Remodeling:
1). Remodeling Units: Osteoblasts and Osteoclast.
2). Bone Deposit:
3). Osteoid Seam: Appears at areas of new bone deposits.
4). Osteoclasts: Release lysosomal enzymes and acids on to bones
surfaces to be reabsorbed.
5). Hormonal Mechanism of Bone Remodeling: Series of blood
calcium homeostasis. PTH (ParaThyroid Hormone) is released and
stimulates osteoclasts to digest bone matrix. When calcium levels
rise, calcitonin released, stimulates the removal from calcium from
the blood.
6). Bone Repair- Fractures are treated by open or closed reduction.
Closed Reduction- The bone ends are coaxed into position by the
physician hands.
Open Reduction- The bone ends are surgically secured with pins or
wires.
1). Hematoma Formation:
2). Fibrocartilaginous Callus Formation:
3). Bony Callus Formation (A week to 2 months)
4). Bone Remodeling