Chapter 5 Study Guide _ Top Hat

Chapter 5: Bones and Axial Skeleton Study Guide Summary

Learning Objectives

  • L.O. 5.1 Name axial skeleton bones.

  • L.O. 5.2 Describe locations of axial skeleton bones.

  • L.O. 5.3 Explain interactions of axial bones with neighboring bones and tissues.

  • L.O. 5.4 Analyze bone histology and its impact on bone properties and function.

  • L.O. 5.5 Describe skeleton as an integrated organ system contributing to homeostasis.

  • L.O. 5.6 Discuss causes and prevention of osteoporosis.

Categories of Bones

  • Axial Bones: Skull, vertebral column, sternum, ribs.

  • Appendicular Bones: Upper and lower limb bones; girdles supporting limbs.

Features of Bones

  • Structure:

    • Layers: Periosteum (outer), compact bone (middle), spongy bone (innermost).

    • Long Bone Structure: Diaphysis (shaft) and epiphyses (ends).

  • Classification of Bones:

    • Long, short, flat, sesamoid, irregular.

  • Bone Markings: Includes depressions (5 types), openings (3 types), projections (10 types).

Bone Tissue Composition

  • Cell Types: Marrow cells, osteoblasts, osteoclasts, osteocytes, osteoprogenitor cells (only mitotically dividing bone cells).

  • Histology:

    • 65% inorganic matrix (primarily hydroxyapatite).

    • 35% organic matrix (collagen, glycoproteins, proteoglycans).

  • Osteons (Haversian Systems): Structural units of compact bone including concentric lamellae and central canals.

  • Spongy Bone: Contains trabeculae; lacks osteons but has lacunae housing osteocytes.

Osteoporosis

  • A condition resulting in porous and weak bones due to imbalance in osteoclast and osteoblast activity, prevalent in aging individuals, especially women post-menopause.

  • Prevention: Balanced diet, adequate calcium/vitamin D intake, active lifestyle, avoidance of smoking and excess alcohol.

Axial Skeleton Overview

  • Components: 22 skull bones, vertebral column, hyoid bone, ribs, sternum.

  • Protection: Skull protects the brain; vertebral column supports and protects the spinal cord.

  • Sternum & Ribs: Form thoracic cage, protecting vital organs such as heart and lungs.

  • Skull: 8 cranial bones (frontal, occipital, ethmoid, sphenoid, temporal, parietal) and 14 facial bones (mandible, vomer, maxillary, zygomatic, nasal, lacrimal, palatine, inferior nasal conchae).

Vertebrae and Vertebral Column

  • Structure: 33 total vertebrae (24 individual and 9 fused forming sacrum and coccyx).

  • Types of Vertebrae: Cervical (C1-C7), thoracic (T1-T12), lumbar (L1-L5), sacral, coccygeal.

  • Functionality: Facilitates movement and protects the spinal cord; includes specific processes for muscle attachment.

Sternum and Ribs

  • Structure: Sternum (3 parts: manubrium, body, xiphoid process); 12 pairs of ribs.

  • Rib Classifications: True ribs (1-7), false ribs (8-12), floating ribs (11-12).

  • Function: Provides support and protection for thoracic organs.