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Understanding Bone Types and Characteristics

Apr 21, 2025

Classification of Bones

Overview

  • The SEER Training Website is a resource for oncology data specialists and cancer registration trainees.
  • The module is part of the Anatomy & Physiology section, focusing on the skeletal system.

Types of Bones

The human body contains four principal types of bones:

Long Bones

  • Characteristics: Longer than they are wide.
  • Structure: Composed mainly of compact bone with spongy bone at the extremities.
  • Examples: Bones of the thigh, leg, arm, and forearm.

Short Bones

  • Characteristics: Cube-shaped; roughly equal dimensions in vertical and horizontal directions.
  • Structure: Primarily spongy bone, covered by a thin layer of compact bone.
  • Examples: Bones of the wrist and ankle.

Flat Bones

  • Characteristics: Thin, flattened, and often curved.
  • Examples: Most of the bones of the cranium.

Irregular Bones

  • Characteristics: Do not fit into the above categories.
  • Structure: Primarily spongy bone with a thin layer of compact bone.
  • Examples: Vertebrae and some skull bones.

Bone Surface Markings

  • Bones have unique surface markings such as holes, depressions, smooth facets, lines, and projections.
  • These markings serve as passageways for vessels and nerves, articulation points with other bones, or attachment points for tendons and ligaments.

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