The Skeletal System
(fat) when animal ages.
Epiphysis End of long bone; end closest to body
is proximal, end farthest is distal.
P Overview:
Diaphysis Cylindrical shaft of long bone between
Osteology: study of bones making up the skeleton, or two epiphyses.
framework of the body. Metaphysis Of a mature bone; flared area adjacent
to epiphysis.
All mammals share basic body plan, differences reflect Epiphyseal Layer of hyaline cartilage within the
adaptations to specific lifestyles. cartilage/Disk metaphysis of an immature bone that
(physis) separates the diaphysis from the
Functions:
epiphysis. (only area in which a bone
P Protect vital organs can lengthen).
P Locomotion Articular cartilage Thin layer of hyaline cartilage that
P Defense/offense covers the articular joint surface of
P Grasping bone.
Periosteum Fibrous membrane that covers the
- All above functions depend largely upon the action of
surface of a bone except where
muscles that attach to levels (which are made of bone
articular cartilage is located.
and integral parts of skeleton). Osteoblasts responsible for increases
P Skeleton serves as dynamic storage area for minerals in diameter of bones; activity of
(Calcium & Phosphorous; deposited and withdrawn as periosteal cells important in healing of
needed in ongoing homeokinetic processes). fractures.
Osteoblasts Bone-producing cells.
Terminology:
Endosteum Fibrous membrane that lines marrow
Compact Hard layer that constitutes the exterior cavity and osteonal canals (osteons) of
(dense/cortical) of most bones; forms entire shaft of bone. Erosion of existing bone by
bone long bones. osteoclasts determines size of marrow
Cancellous Composed of spicules arranged to cavity and thickness of diaphyseal
(spongy) bone form a porous network; spaces filled cortex.
with marrow. Osteoclasts Bone-destroying cells
Medullary cavity Space surrounded by cortex of long
(marrow cavity) bone.
Many of projections from and depressions in bones
In young animals, filled with red
marrow (hematopoietic tissue), have general names depending on size and function.
gradually replaced by yellow marrow
1
, Both projections and depressions may be articular or Protect vital organs (skull protects brain), the heart
nonarticular: and lungs (scapulae and ribs), and the pelvic viscera
- Articular: From an integral part of a joint and covered (pelvis).
with articular cartilage. Provide large areas for attachment of muscles. (i.e.,
- Nonarticular: Exist outside of joints; provide areas for scapulae and pelvis).
attachment of muscle tendons/ligaments.
4. Sesamoid bones
Classification of Bones according to Gross Develop within tendons; increase leverage and protect
Appearance: tendon against forces exerted with a change in the
direction of muscle pull.
1. Long bones
Patella – largest sesamoid bone.
Diaphysis (cylindrical shaft) and epiphyses
(proximal/distal)
Metaphysis between diaphysis and epiphysis.
5. Pneumatic bones
Function as levers
Contain air spaces/sinuses that communicate with the
Aid in support, locomotion and prehension.
atmosphere.
- Example: Humerus, ulna, femur, tibia, fibula
i.e., frontal, and maxillary bones.
Many avian bones are pneumatized.
2. Short bones
Cuboid; approximately equal in all dimensions.
6. Irregular bones
No single marrow cavity: interior composed of spongy
Include vertebrae and some unpaired bones of skull.
bone filled with marrow spaces.
Shapes of bones specific to locations.
Exterior formed by thin layer of compact bone.
Some anatomists include the pelvis in this category.
Absorb concussion.
Found in complex joints: carpus and tarsus, where
variety of movements and absorption of shock occur.
Axial Skeleton
Articulate facets accommodate variety of movements.
Includes bones on/attached to midline (axis) of body.
1. Skull
3. Flat bones
2. Vertebral Column
Relatively thin and expanded in two dimensions.
2
(fat) when animal ages.
Epiphysis End of long bone; end closest to body
is proximal, end farthest is distal.
P Overview:
Diaphysis Cylindrical shaft of long bone between
Osteology: study of bones making up the skeleton, or two epiphyses.
framework of the body. Metaphysis Of a mature bone; flared area adjacent
to epiphysis.
All mammals share basic body plan, differences reflect Epiphyseal Layer of hyaline cartilage within the
adaptations to specific lifestyles. cartilage/Disk metaphysis of an immature bone that
(physis) separates the diaphysis from the
Functions:
epiphysis. (only area in which a bone
P Protect vital organs can lengthen).
P Locomotion Articular cartilage Thin layer of hyaline cartilage that
P Defense/offense covers the articular joint surface of
P Grasping bone.
Periosteum Fibrous membrane that covers the
- All above functions depend largely upon the action of
surface of a bone except where
muscles that attach to levels (which are made of bone
articular cartilage is located.
and integral parts of skeleton). Osteoblasts responsible for increases
P Skeleton serves as dynamic storage area for minerals in diameter of bones; activity of
(Calcium & Phosphorous; deposited and withdrawn as periosteal cells important in healing of
needed in ongoing homeokinetic processes). fractures.
Osteoblasts Bone-producing cells.
Terminology:
Endosteum Fibrous membrane that lines marrow
Compact Hard layer that constitutes the exterior cavity and osteonal canals (osteons) of
(dense/cortical) of most bones; forms entire shaft of bone. Erosion of existing bone by
bone long bones. osteoclasts determines size of marrow
Cancellous Composed of spicules arranged to cavity and thickness of diaphyseal
(spongy) bone form a porous network; spaces filled cortex.
with marrow. Osteoclasts Bone-destroying cells
Medullary cavity Space surrounded by cortex of long
(marrow cavity) bone.
Many of projections from and depressions in bones
In young animals, filled with red
marrow (hematopoietic tissue), have general names depending on size and function.
gradually replaced by yellow marrow
1
, Both projections and depressions may be articular or Protect vital organs (skull protects brain), the heart
nonarticular: and lungs (scapulae and ribs), and the pelvic viscera
- Articular: From an integral part of a joint and covered (pelvis).
with articular cartilage. Provide large areas for attachment of muscles. (i.e.,
- Nonarticular: Exist outside of joints; provide areas for scapulae and pelvis).
attachment of muscle tendons/ligaments.
4. Sesamoid bones
Classification of Bones according to Gross Develop within tendons; increase leverage and protect
Appearance: tendon against forces exerted with a change in the
direction of muscle pull.
1. Long bones
Patella – largest sesamoid bone.
Diaphysis (cylindrical shaft) and epiphyses
(proximal/distal)
Metaphysis between diaphysis and epiphysis.
5. Pneumatic bones
Function as levers
Contain air spaces/sinuses that communicate with the
Aid in support, locomotion and prehension.
atmosphere.
- Example: Humerus, ulna, femur, tibia, fibula
i.e., frontal, and maxillary bones.
Many avian bones are pneumatized.
2. Short bones
Cuboid; approximately equal in all dimensions.
6. Irregular bones
No single marrow cavity: interior composed of spongy
Include vertebrae and some unpaired bones of skull.
bone filled with marrow spaces.
Shapes of bones specific to locations.
Exterior formed by thin layer of compact bone.
Some anatomists include the pelvis in this category.
Absorb concussion.
Found in complex joints: carpus and tarsus, where
variety of movements and absorption of shock occur.
Axial Skeleton
Articulate facets accommodate variety of movements.
Includes bones on/attached to midline (axis) of body.
1. Skull
3. Flat bones
2. Vertebral Column
Relatively thin and expanded in two dimensions.
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