Chapter 2
Skeletal System
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Davis Company
Objectives
Describe the functions of the skeleton
Differentiate axial and appendicular
skeleton
Recognize and describe the composition
of bone
Identify and explain the structure of the
bone
Recognize and identify the types of bones
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Davis Company
Skeletal System Functions
Support - for soft tissues of the body
Movement - bones serve as levers and
joints as fulcrum
Protection - vital organs
Mineral Storage - calcium and
phosphorous
Production of blood cells (hematopoiesis)
Provide shape
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Davis Company
Types of Skeletons
Axial Skeleton upright part of
body; 80 bones of
the head, thorax,
and trunk
Appendicular
Skeleton - 126
bones of the
extremities
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Davis Company
Types of Skeletons
Axial Skeleton
Upright part of
body; 80 bones of
the head, thorax,
and trunk
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Davis Company
Types of Skeletons
Appendicular Skeleton
126 bones of the
extremities
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Davis Company
Bones of the Human Body
Axial Skeleton
Single
Paired
Multiple
Cranium (8)
Frontal
Sphenoid
Ethmoid
Occipital
Parietal
Temporal
None
Face (14)
Mandible
Vomer
Maxilla
None
Zygomatic
Lacrimal
Inferior concha
Palatine
Nasal
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Davis Company
Bones of the Human Body
Axial Skeleton (cont’d)
Single
Paired
Multiple
Other (7)
Hyoid
Ear ossicles
(3)
None
Vertebral column (26)
Sacrum (5)*
Coccyx (3)*
None
Cervical (7)
Thoracic (12)
Lumbar (5)
Thorax (25)
Sternum
Ribs (12 pairs) None
True (7)
False (3)
Floating (2)
*Bones are fused together.
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Davis Company
Bones of the Human Body
Appendicular Skeleton (cont’d)
Upper extremity (64)
Single
None
Paired
Scapula
Clavicle
Humerus
Ulna
Radius
Multiple
Carpals (8)
Metacarpals (5)
Phalanges (14)
Lower Extremity (62)
None
Hip (3)*
Femur
Tibia
Fibula
Patella
Tarsals (7)
Metatarsals (5)
Phalanges (14)
*Bones are fused together.
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Davis Company
Composition of Bones
Among body’s hardest structures, only
dentin and enamel in teeth harder
Dynamic and metabolically active
throughout life
Vascularized - self repairing and
remodeling
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Davis Company
Composition of Bones (cont’d)
An organ - made up of several different
types of tissue
fibrous, cartilaginous, osseous, nervous, and vascular
function as integral parts of the skeletal system
1/3 Organic (living) material
organic gives bone elasticity
2/3 Inorganic (non-living) material
inorganic provides bone hardness and strength
Copyright 2001, F. A.
Davis Company
Bone is a specialized connective tissue
Composition of Bones (cont’d)
Consists of cells and an organic extracellular
matrix of fibers and ground substances
produced by the cells
High content of inorganic materials, in the
form of mineral salts, calcium, and phosphate
Collagen composes ~95% or the extracellular
matrix (25-30% of the dry weight)
Water - abundant, 25% of total weight
Copyright 2001, F. A.
Davis Company
Microscopic Level
Composition of Bones (cont’d)
Osteon
Fundamental unit of bone
Haversian Canal
Small channel at center of each osteon
Contains blood vessels and nerve supply
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Davis Company
Macroscopic Level
Composition of Bones (cont’d)
Compact or Cortical Bone
Hard, dense outer shell
Completely covers bone
Thick along shaft and plates of flat bones
Thin at ends of long bones
Cancellous or Trabecullar Bone
Porous and spongy inside portion
Same material as compact bone but, more porous and
contains less solid material
Loose mesh structure or pores filled with marrow → lighter
Makes up most of articular ends of bone
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Davis Company
Structure of Bone
Epiphysis
Area at each end of
the diaphysis
Wider than the shaft
Adult bones - osseous
Growing bones cartilaginous and
called epiphyseal plate
Epiphyseal plate manufactures new
bone
Copyright 2001, F. A.
Davis Company
Structure of Bone
(cont’d)
Diaphysis
Main shaft of bone
Primarily compact
Medullary canal passage for nutrient
arteries
Endosteum - for bone
resorption
Metaphysis - primarily
cancellous, provides
support
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Davis Company
Structure of Bone
(cont’d)
Periosteum
Thin fibrous membrane
Covering all of the bone except
articular surface
Contains nerve and blood
vessels
Function:
⌧Nourishment
⌧Growth in diameter of immature
bone
⌧Repair of the bone
⌧Attachment for tendons and
ligaments
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Davis Company
Types of Bones
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Davis Company
Types of Bones (cont’d)
Long Bones
Length > width
Tubular shaped with
shaft and bulbous
ends
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Types of Bones
Short Bones
Dimensions equal
Cubical shape
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(cont’d)
Types of Bones (cont’d)
Flat Bones
Broad surface
Not thick
Examples:
Scapula
Ilium
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Types of Bones (cont’d)
Irregular Bones
Variety of mixed
shapes
Examples
Sacrum
Vertebra
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Types of Bones (cont’d)
Sesamoid Bones
Small bones resembling sesame seeds
Located where tendons cross long bones
Change the angle of attachment
Protect from excessive wear
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Davis Company
Types of Bones
Appendicular Upper
Skeleton
Extremity
Long bones
Lower
Extremity
Short bones
HumerusFemur
Radius
Ulna
Metacarpals
Phalanges
Carpals
Flat bones
Scapula
Ilium
Patella
Irregular bones
None
None
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(cont’d)
Fibula
Tibia
Metatarsals
Phalanges
Tarsals
Axial Skeleton
Clavicle
None
Cranial bones (frontal,parietal)
Ribs
Sternum
Vertebrae
Cranial bones (sphenoid,ethmoid)
Sacrum
Coccyx
Mandible
Facial bones
Bone Markings
Depressions and Openings
Marking
Foramen
Fossa
Groove
Meatus
Sinus
Description
Hole through which blood
vessels, nerves, and ligaments
pass
Hollow or depression
Ditchlike groove containing a
tendon or blood vessel
Canal or tubelike opening in
a bone
Air-filled cavity within a bone
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Examples
Vertebral foramen of
cervical vertebra
Glenoid fossa of scapula
Bicipital (intercondylar)
groove of humerus
External auditory
meatus
Frontal sinus in frontal
bone
Bone Markings (cont’d)
Projections/Processes that Fit into Joints
Marking
Condyle
Eminence
Facet
Head
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Description
Rounded knuckle-like
projection
Projecting, prominent part
of bone
Flat or shallow articular
surface
Rounded articular projection
beyond a narrow necklike
portion of bone
Examples
Medial condyle of femur
Intercondylar eminence,
tibia
Articular facet of rib
Femoral head
Bone Markings
(cont’d)
Projections/Processes for Attachment
Marking
Crest
Epicondyle
Tubercle
Description
Sharp ridge or border
Prominence above or on a
condyle
Less prominent ridge
Long, thin projection
Very large prominence for
muscle attachment
Small, rounded projection
Tuberosity
Larger, rounded projection
Line
Spine
Trochanter
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Examples
Iliac crest of hip
Medial epicondyle of
humerus
Linea aspera of femur
Scapular spine
Greater trochanter of
femur
Greater tubercle of
humerus
Ischial tuberosity