Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

6. Bones & Skeletal Tissue

Gross Anatomy of Bones - Structure of a Long Bone

Anatomy & Physiology

6. Bones & Skeletal Tissue

Gross Anatomy of Bones - Structure of a Long Bone

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2:14 minutes

Problem 20

Textbook Question

Why are stresses or impacts to the side of the shaft in a long bone more dangerous than stress applied to the long axis of the shaft?

Verified step by step guidance

Understand the structure of a long bone: A long bone consists of a diaphysis (shaft) and two epiphyses (ends). The diaphysis is primarily composed of compact bone, which is dense and provides strength, while the epiphyses contain spongy bone, which absorbs shock.

Recognize the orientation of stress: Stress applied along the long axis of the shaft (axial stress) aligns with the natural structure of the bone, which is designed to resist compression and tension in this direction. The compact bone's arrangement of osteons (cylindrical structures) supports this type of stress effectively.

Contrast with lateral stress: Stress or impact applied to the side of the shaft (lateral stress) creates bending forces. These forces generate tension on one side of the bone and compression on the other, which the bone is less equipped to handle compared to axial stress.

Consider the risk of fracture: The compact bone is more likely to fracture under lateral stress because it is not as resistant to bending forces. Additionally, the periosteum (outer covering of the bone) and surrounding soft tissues may also be damaged by lateral impacts.

Conclude the danger: Stresses or impacts to the side of the shaft are more dangerous because they exploit the bone's structural weaknesses, leading to a higher likelihood of fractures and associated injuries compared to stress applied along the long axis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Bone Mechanics

Bone mechanics refers to the study of how bones respond to various forces and stresses. Long bones, such as the femur or humerus, are designed to withstand axial loads (forces along their length) effectively. However, they are more vulnerable to bending and shear stresses when forces are applied laterally, which can lead to fractures or structural failure.

Stress Distribution

Stress distribution is the way in which forces are spread across a material. In long bones, axial stress is distributed evenly along the length, allowing for efficient load-bearing. Conversely, lateral stresses create uneven distribution, leading to concentrated areas of stress that can exceed the bone's strength, resulting in injury.

Fracture Types

Fracture types are classifications of bone breaks based on the nature of the force applied. Longitudinal fractures typically occur from axial stress, while transverse or oblique fractures often result from lateral impacts. Understanding these types helps in assessing the risk and severity of injuries related to different stress orientations on bones.