Lab 4B-BIO 105
Classification of Bones: by Shape
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• Long bones
– Longer than wide (i.e. humerus, femur)
• Short bones
– Cube-shaped bones (i.e. wrist and ankle)
– Bones that form within tendons e.g. patella
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Classification of Bones by Shape
• Flat bones
• Thin, flat, slightly curved (i.e. skull, sternum)
• Irregular bones -almost impossible to describe the shape
• Complicated shapes (i.e. vertebrae, hip)

Functions of Bones
1. Support: For the body and soft organs
2. Protection: For brain, spinal cord, and vital organs
3. Movement: Muscles attached to bones act as levers
4. Storage: Minerals (calcium and phosphorus) and growth factors
• Triglycerides (fat)
5. Blood cell formation (hematopoiesis) in marrow cavities
6. Hormone production

Gross anatomy :
• Compact bone
– Dense outer layer
• Spongy (cancellous) bone
– Honeycomb of trabeculae filled with bone marrow
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Long Bone Structure
• Diaphysis (shaft)-tube-like center of bone
– Compact bone surrounds medullary (marrow) cavity
– Medullary cavity in children contains red bone marrow; in adults contains yellow marrow (fat)
• Epiphyses-ends of long bones
– Spongy bone interior
– Epiphyseal line (remnant of growth plate)separates diaphysis and epiphysis
– Joint surfaces covered with articular (hyaline) cartilage
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Spongy Bone
• Trabeculae
– No osteons
– Contain irregularly arranged lamellae, osteocytes, and canaliculi
– Capillaries in endosteum (innermost lining membrane) supply nutrients
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Membranes of Bone
• Periosteum—double layered; very strong , leathery,
– Outer layer: dense regular connective tissue
– Inner osteogenic layer
• Osteoblasts (bone-forming cells)
• Osteoclasts (bone-destroying cells)
• Osteogenic cells (stem cells)
– Has nerve fibers, blood vessels, and lymphatic vessels which enter bone via nutrient foramina
• Endosteum
– Delicate membrane on internal surfaces of bone; primarily areolar tissue
– Also contains osteoblasts and osteoclasts
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Microscopic Anatomy of Bone: Compact Bone
• Haversian system, or osteon—structural unit
– Lamellae
• Weight-bearing
• Column-like matrix tubes
– Central (Haversian) canal
• Contains blood vessels and nerves
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• Volkmann’s (Perforating) canals
– At right angles to central canal
– Connects blood vessels and nerves of periosteum with central canal
• Lacunae—small cavities that contain osteocytes
• Canaliculi— hair like canals that connect lacunae to each other and central canal
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Bone Markings: Depressions and Openings
• Meatus- canal-like passageway
• Fossa-shallow depression
• Sinus-cavity within a bone
• Groove-shallow depression
• Fissure-narrow, slit-like opening
• Foramen-opening through a bone
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Bone Markings: Projections
Sites of muscle and ligament attachment
1. Tuberosity—rounded projection
2. Crest—narrow, prominent ridge
3. Trochanter—large, blunt, irregular surface
4. Line—narrow ridge of bone
5. Tubercle—small rounded projection
6. Epicondyle—raised area above a condyle
7. Spine—sharp, slender projection
8. Process—any bony prominence
9. Condyle -- Rounded articular projection
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• Projections: help to form joints
– Head--Bony expansion on a narrow neck
– Facet-Smooth, nearly flat articular surface
– Condyle-Rounded articular projection
– Ramus-Armlike bar
LABWORK
1. List, identify, and describe the different types of bones and long bone structure specifically.
2. List, identify, and describe items associated with the microscopic structure of bone tissue.
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