182
UNIT 2
Covering, Support, and Movement of the Body
6
Chemical Composition of Bone
Bone contains both organic and inorganic substances.
Organic
components
include bone cells and osteoid. Its
inorganic compo-
nents
are mineral salts.
Only a few cells thick, trabeculae contain irregularly arranged
lamellae and osteocytes interconnected by canaliculi. No oste-
ons are present. Nutrients reach the osteocytes of spongy bone
by diffusing through the canaliculi from capillaries in the en-
dosteum surrounding the trabeculae.
(a)
(b)
(c)
Compact bone
Spongy bone
Endosteum lining bony canals
and covering trabeculae
Perforating
(Volkmann’s) canal
Perforating (Sharpey’s) fibers
Periosteal blood vessel
Periosteum
Interstitial
lamella
Lacunae
Lamellae
Lamellae
Nerve
Vein
Artery
Canaliculi
Osteocyte
in a lacuna
Circumferential
lamellae
Osteon
(Haversian system)
Central
(Haversian) canal
Central
canal
Lacuna (with osteocyte)
Figure 6.7
Microscopic anatomy of compact bone.
(a)
Diagram of a pie-shaped segment
of compact bone.
(b)
Close-up of a portion of one osteon. Note the position of osteocytes in
the lacunae.
(c)
SEM (left) of cross-sectional view of an osteon (410
3
). Light photomicrograph
(right) of a cross-sectional view of an osteon (410
3
).
previous page 216 Human Anatomy and Physiology (9th ed ) 2012 read online next page 218 Human Anatomy and Physiology (9th ed ) 2012 read online Home Toggle text on/off