Chapter 3 Skeletal System
FUNCTIONS OF BONES
Shape, support, protection, movement storage of minerals, blood cell formation, Classification
of bone
CLASSIFICATION OF BONE BY DENSITY CLASSIFICATION OF BONE BY SHAPE
compact bone → dense Flat
spongy (trabecular, cancellous) bone → porous Long
Short
Irregular
Sesamoid
MAJOR FEATURES OF BONE
head: Enlarged, neck: constricted body: main portion Facet: Small Condyle: rounded,
rounded end area attaches head Flattened joint knuckle-like
to body surface
PROJECTIONS RIDGE
Process: prominent Tuberosity: large rounded Trochanter: large blunt Crest: thin Spine: sharp
projection prominence process ridge of bone ridge
Mastoid, Zygomatic deltoid tuberosity on the femur iliac crest anterior
superior iliac
spine
DEPRESSIONS OPENING
Fossa: shallow depression Foramen: round or oval opening Meatus: tubular passage Sinus: air-filled
iliac fossa (plural of foramen is foramina) cavity
HISTOLOGY OF BONE
connective tissue; cells separated by hard matrix
OSTEOPROGENITOR CELLS OSTEOBLASTS OSTEOCYTES OSTEOCLASTS
• undifferentiated cells • surface cells • mature bone cells • large cells formed from
• surface cells (found on inner • form matrix and • osteoblasts surrounded fused monocytes
layer of periosteum, collagen fibers by matrix, enclosed in (osteoprogenitor )
endosteum) • Become osteocytes • maintain bone tissue but • surface cells
• can divide to replace when surrounded by do not produce new matrix • secrete enzymes that
themselves OR matrix • can’t divide dissolve bone matrix
can → osteoblasts • can’t divide • function in bone growth,
repair, remodeling
fill the blank
Bone Remodeling
• Osteoclasts continuously carve out tunnels, osteoblasts rebuild osteons
• Bone matrix is continuously redistributed along lines of mechanical stress
Bone matrix
not completely solid 25% water mineralization (calcification) -
has small spaces for vessels 25% organic matrix (collagen fibers hardening of tissue when mineral
and red bone marrow → strength, flexibility) crystals deposit around collagen
spongy bone has many 50% inorganic matrix (mineral salts fibers
spaces → hardness)
compact bone has less spaces
COMPACT OR DENSE BONE SPONGY BONE
• Solid hard layer of bone • latticework of thin plates of bone called
• Forms shaft of long bones, external surface of all bones trabeculae oriented along lines of stress
FUNCTIONS OF BONES
Shape, support, protection, movement storage of minerals, blood cell formation, Classification
of bone
CLASSIFICATION OF BONE BY DENSITY CLASSIFICATION OF BONE BY SHAPE
compact bone → dense Flat
spongy (trabecular, cancellous) bone → porous Long
Short
Irregular
Sesamoid
MAJOR FEATURES OF BONE
head: Enlarged, neck: constricted body: main portion Facet: Small Condyle: rounded,
rounded end area attaches head Flattened joint knuckle-like
to body surface
PROJECTIONS RIDGE
Process: prominent Tuberosity: large rounded Trochanter: large blunt Crest: thin Spine: sharp
projection prominence process ridge of bone ridge
Mastoid, Zygomatic deltoid tuberosity on the femur iliac crest anterior
superior iliac
spine
DEPRESSIONS OPENING
Fossa: shallow depression Foramen: round or oval opening Meatus: tubular passage Sinus: air-filled
iliac fossa (plural of foramen is foramina) cavity
HISTOLOGY OF BONE
connective tissue; cells separated by hard matrix
OSTEOPROGENITOR CELLS OSTEOBLASTS OSTEOCYTES OSTEOCLASTS
• undifferentiated cells • surface cells • mature bone cells • large cells formed from
• surface cells (found on inner • form matrix and • osteoblasts surrounded fused monocytes
layer of periosteum, collagen fibers by matrix, enclosed in (osteoprogenitor )
endosteum) • Become osteocytes • maintain bone tissue but • surface cells
• can divide to replace when surrounded by do not produce new matrix • secrete enzymes that
themselves OR matrix • can’t divide dissolve bone matrix
can → osteoblasts • can’t divide • function in bone growth,
repair, remodeling
fill the blank
Bone Remodeling
• Osteoclasts continuously carve out tunnels, osteoblasts rebuild osteons
• Bone matrix is continuously redistributed along lines of mechanical stress
Bone matrix
not completely solid 25% water mineralization (calcification) -
has small spaces for vessels 25% organic matrix (collagen fibers hardening of tissue when mineral
and red bone marrow → strength, flexibility) crystals deposit around collagen
spongy bone has many 50% inorganic matrix (mineral salts fibers
spaces → hardness)
compact bone has less spaces
COMPACT OR DENSE BONE SPONGY BONE
• Solid hard layer of bone • latticework of thin plates of bone called
• Forms shaft of long bones, external surface of all bones trabeculae oriented along lines of stress
