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Questions and Answers
Which of the following is NOT a part of the skeletal system?
How many bones does the adult human skeleton have?
206
What does the axial skeleton consist of?
Which type of bone is primarily composed of a network of small, bony plates?
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What is the primary function of ligaments?
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What is housed in the medullary cavity of a long bone in adults?
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Short bones are typically longer than they are wide.
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Which of the following is an example of a flat bone?
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What is the function of the periosteum?
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The four main types of bone classifications are long, short, flat, and ______.
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Match the following types of bone with their description:
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Study Notes
Parts of the Skeletal System
- Composed of bones (skeleton), joints, cartilages, and ligaments.
Divisions of the Skeletal System
-
Axial Skeleton:
- Contains 80 bones.
- Forms the body's framework, including the head and trunk.
-
Appendicular Skeleton:
- Contains 126 bones.
- Provides the framework for limbs, shoulders, and hips.
Functions of Bones
- Support: Acts as a firm framework for the body.
- Protection: Shields soft organs from injury.
- Movement: Works with attached skeletal muscles as levers.
- Storage: Holds minerals (calcium salts) and fats.
- Blood Cell Formation: Produces blood cells in red marrow.
Bone Characteristics
- An adult skeleton typically has 206 bones.
- Two main types of bone tissue:
-
Compact Bone:
- Hard, dense structure forming the main shaft and outer layer of bones.
-
Spongy Bone:
- Contains more spaces, forming a meshwork filled with red marrow.
- Found at the ends of long bones and at the center of other bones.
-
Compact Bone:
Bone Classifications
-
Long Bones:
- Longer than wide, with shafts and heads at both ends. Mostly compact bone.
- Examples: Femur, humerus.
-
Short Bones:
- Cube-shaped, primarily composed of spongy bone.
- Examples: Carpals, tarsals.
-
Flat Bones:
- Thin, flattened, usually curved, with layers of compact bone surrounding spongy bone.
- Examples: Skull, ribs, sternum.
-
Irregular Bones:
- Unusual shapes that do not fit into other categories.
- Examples: Vertebrae, hip bones.
Gross Anatomy of Long Bone
-
Diaphysis:
- The shaft made of compact bone.
-
Epiphysis:
- The ends composed mainly of spongy bone.
Structures of a Long Bone
-
Periosteum:
- Fibrous connective tissue covering the diaphysis.
-
Sharpey’s Fibers:
- Secure periosteum to the underlying bone.
-
Arteries:
- Supply nutrients to bone cells.
-
Medullary Cavity:
- Contains yellow marrow (fat) in adults; red marrow (blood cell formation) in infants.
-
Articular Cartilage:
- Covers external surfaces of epiphyses, decreasing joint friction.
Bone Markings
- Surface features that serve as muscle, tendon, and ligament attachment points and provide passages for nerves and blood vessels.
Bone Projections
- Head: Rounded knob-like end on a bone.
- Process: Large projection (e.g., ulna in the forearm).
- Condyle: A rounded projection; an epicondyle is above a condyle.
- Crest: Distinct, often rough border or ridge.
- Spine: A sharp projection from a bone surface.
Depressions and Holes
- Foramen: Hole allowing vessels or nerves to pass.
- Sinus: Air space in some skull bones.
- Fossa: Depression on a bone surface.
- Meatus: Short channel, such as the ear canal in the temporal bone.
Microscopic Anatomy of Bone
- Osteon (Haversian System): Fundamental bone unit.
- Central Canal (Haversian Canal): Contains blood vessels and nerves.
- Perforating Canal (Volkman's Canal): Runs perpendicular to the central canal, carrying blood vessels and nerves.
- Lacunae: Cavities housing bone cells (osteocytes), arranged in concentric rings.
- Canaliculi: Tiny canals connecting lacunae to the central canal, facilitating transportation.
- Lamellae: Rings around the central canal containing sites for lacunae.
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Description
Test your knowledge on the skeletal system, including its parts such as bones, joints, and ligaments. Explore the differences between the axial and appendicular skeleton and their functions. This quiz covers fundamental concepts essential for understanding human anatomy.
