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Support – form the internal framework that
support and anchor our organs and let us stand
upright
Protection – Keeps organs from being
damaged (like the skull protects the brain)
Movement – Act as leverage points for muscles
Storage – fat and other minerals are stored in
bones
Blood Cell Formation – occurs in bone marrow
There are 206 bones in
the adult skeleton.
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Compact Bone – dense, looks smooth and
homogenous
Spongy Bone – composed of small needlelike
pieces of bone and lots of open spaces
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Long Bones – typically longer than they are
wide. Usually have a shaft with two heads on
each side and are mostly compact bone.
Short Bones – Generally cubed shape and
contain mostly spongy bone
Flat Bones – thin, flattened, and usually curved.
Two layers of compact bone sandwich a layer of
spongy
Irregular Bones – odd shaped that don’t fit into
the other categories.
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Process – any bony prominence (projection)
Tuberosity – large rounded projection
Crest – narrow ridge of bone
Line – narrow ridge of bone that is less
prominent than a crest
Trochanter – Very large, blunt, irregularly shaped
process
Tubercle – Small, rounded projection or process
Epicondyle – A raised area on or above a condyle
Spine – Sharp, slender, often pointed projection
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Head – Bony expansion carried on a narrow neck
Facet – smooth, nearly flat articular surface
 Articular - of or relating to a joint
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Condyle – rounded articular projection
Ramus – armlike bar of bone
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Meatus – Canal-like passageway
Sinus – cavity within a bone, filled with air and
lined with mucous membrane
Fossa – Shallow, basinlike depression in a bone
Groove – Furrow
Fissure – Narrow, slitlike opening
Foramen – Round or oval opening through a
bone
Hint – projections start with T, depressions start
with F (except for facet)
Diaphysis – the shaft. Makes up length of bone and is
made up of compact bone.
 Periosteum – bone cover. A fibrous connective tissue
membrane that covers and protect the bone.
 Endosteum – covering found in the middle of the
bone around the medullary cavity.
 Perfotaring or Sharpey’s Fibers – connect periosteum
to the underlying bone.
 Epiphyses – ends of bones. Compact bone on the
outside, spongy inside.
 Articular Cartilage – covers ends of bone. It is hyaline
cartilage, which makes a smooth, slippery surface
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Epiphyseal Line – remnants of the epiphyseal
plate
 Epiphyseal plate – site of cartilage where new
bone growth occurs in young bones. After
maturation, it turns to bone.
 Medullary or Yellow Marrow Cavity – located in
the center of the shaft, it is a site of adipose
storage
 Red Marrow – during infancy, blood cells are
made in the center of the shaft. Later in life, this
is namely preformed in spongy bone of flat
bones.
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Osteocytes – mature bone cells
Lacunae – the matrix the bone cells are in
Lamellae – a concentric circle pattern that the
lacunae make
 Haversian or central canal – center of circle
 Haversian or osteon system – this is a complex
consisting of the central canal and matrix rings
around it
 Canaliculi – tiny canals that radiate outward from
the central canal (transport system)
 Perforating or Volkmann’s canal – pathway from the
outside of the bone to its interior
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Ossification – bone formation
 Most bones start as hyaline cartilage
 The cartilage model gets covered in bone forming
cells call osteoblasts
 Enclosed cartilage is digested away, leaving the
medullary cavity.
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To grow longer, the answer is the epiphyseal
plate.
 New cartilage is formed on the side of the plate
furthest from the medullary cavity.
 At the same time, old cartilage near the medullary
cavity is broken down and replaced by a bony
matrix
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To grow wider, osteoblasts in the periosteum
add bone tissue as osteoclast in the
endosteum remove bone from the inner wall
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Bone is remodeled (changed) all the time in
response to:
 Calcium levels
▪ When calcium in the blood drops, parathyroid glands are
stimulated releasing parathyroid hormone. This activates
osteoclasts (bone destroying cells). These break down cells and
release calcium back into the blood stream
▪ If calcium is too high, calcium is deposited in the bone matrix as
hard calcium salts
 Pull of gravity and muscles
▪ The body will thicken or thin areas depending on the stresses
from different pulls. More pull = more bone to strengthen area