The Skeletal System

Parts of the skeletal system
Two subdivisions of the skeleton
 Axial skeleton
 Appendicular
skeleton
Two subdivisions of the skeleton
 Adult skeleton approximately 206 bones
 Axial: 80 bones
 Appendicular: 126 bones
Two basic types of bone tissue
 Compact bone
 Homogeneous
 Spongy bone
 Many open spaces
Classification of Bones based on Shape
Classification of Bones based on Shape
Classification of Bones based on Shape
Classification of Bones based on Shape
Classification of Bones based on Shape
Anatomy of a Long Bone
 Epiphysis
Anatomy of a Long Bone
Anatomy of a Long Bone
 Diaphysis
Anatomy of a Long Bone
 Periosteum
 Sharpey’s fibers
 Arteries
Anatomy of a Long Bone
Anatomy of a Long Bone
Anatomy of a Long Bone
 Articular cartilage
 Covers surface of the
epiphyses
Anatomy of a Long Bone
 Epiphyseal plate
 Epiphyseal line
Anatomy of a Long Bone
Anatomy of a Long Bone
 Medullary cavity
 Cavity inside of the shaft
Bone Markings
 Are bones smooth
surfaces?
 Femur
 Are bones smooth
surfaces?
 Tibia
Bone Markings
 Are bones smooth
surfaces?
 Mandible
Bone Markings
 Are bones smooth
surfaces?
 Optical canal
Compact vs. Spongy bone
Microscopic Anatomy of Compact Bone
 Osteocytes: mature bone cells
 Lacunae:
Microscopic Anatomy of Compact Bone
 Lamella:
Microscopic Anatomy of Compact Bone
 Central (Haverersian) Canals:
Microscopic Anatomy of Compact Bone
 Osteon (Haversian System):
Microscopic Anatomy of Compact Bone
Microscopic Anatomy of Compact Bone
 Canaliculi:
 Hint: which way do
central canals run?
Microscopic Anatomy of Compact Bone
Microscopic Anatomy of Compact Bone
 This eleaborate network of canals ensures bone
cells are well nourished
 What significance does this have?
 Perforating (Volkmann’s) canals:
Microscopic Anatomy of Compact Bone
Bone Formation, Growth, & Remodeling
 Mostly hyaline
cartilage
 Replaced by
bone
Bone Formation, Growth, & Remodeling
Articular
cartilage
Hyaline
cartilage
Spongy
bone
New center of
bone growth
New bone
forming
Epiphyseal
plate
cartilage
Growth
in bone
width
Medullary
cavity
Bone starting
to replace
cartilage
Growth
in bone
length
Blood
vessels
New bone
forming
Bone collar
Epiphyseal
plate cartilage
Hyaline
cartilage
model
In an embryo
(a)
In a fetus
In a child
Bone Formation, Growth, & Remodeling
 Osteocytes—mature bone cells
 Osteoblasts—bone-forming cells
 Osteoclasts—bone-destroying cells
Growth & Remodeling
 New cartilage is
continuously formed
 Older cartilage becomes
ossified
Growth & Remodeling
 Osteocytes can sense
areas of stress
 Enhances the process
 Balance of calcium levels
Fractures
Fractures
Fractures
Fractures
Fractures
Fractures
Fractures
 Treated by Reduction:
 Closed
 Open