Osteology and Arthrology for First Aid

The information posted on this article is additional material to supplement basic first aid training. This content will not be included in any detail in standard, childcare or emergency first aid programs. This article supplements the sprains and strains and broken bones components of Red Cross first aid training.


A. Functions of the Skeleton
• Provides a supporting framework for the body
• Provides attachment points for muscles, creating a lever system that enables body movement
• Provides protection of vital organs
• Blood cell formation – red bone marrow produces red and white blood cells and platelets. Bone is richly supplied with blood vessels.
• Mineral storage – calcium and phosphorus

B. Structure of Bone
The major building blocks of bone are calcium carbonate, calcium phosphate, collagen fibers, and water. Collagen is a protein that is the main organic constituent of connective tissue. Bone tissue is composed of widely separated cells, called osteocytes, surrounded by matrix. The matrix is about 25% water, 25% protein, and 50% mineral salts. Bone is highly dynamic and is continually being remodeled in response to mechanical stress or even absence of stress. Longitudinal growth of a bone occurs at the epiphyseal plate, which is a layer of cartilage. The proliferating cartilage cells are gradually replaced by bone. The bones of physically active individuals tend to be denser and therefore more mineralized than those of sedentary individuals of the same age and gender.

C. Classification of Bones

  • Long bones
  • Short bones
  • Flat bones
  • Irregular bones

D. Vertebral Column
The vertebral column provides flexible support for the trunk and protects the spinal

  • 33 vertebrae; 26 distinct bones
  • 5 segments
  • 7 cervical vertebrae
  • 12 thoracic vertebrae
  • 5 lumbar vertebrae
  • 5 sacral vertebrae
  • 4 coccygeal vertebrae

The vertebrae articulate with one another by means of facets on the processes of the neural arches (synovial joint) and by means of intervertebral discs between the vertebral bodies (cartilaginous joint). The discs function as shock absorbers and allow slight movement so that the column is flexible and resilient.

Abnormal curves:
1. Scoliosis – an abnormal lateral curvature of the vertebral column.
2. Kyphosis – “hump back” – an exaggerated posterior thoracic curve.
3. Lordosis – “sway back” – an exaggerated anterior lumbar curve.

E. Classification of Joints

  1. Fibrous joint – immoveable
  2. Cartilaginous joint – slightly moveable
  3. Synovial joint – freely moveable

Synovial fluid has two functions:
a) Lubricates the joint surfaces as they slide over each other during joint movement
b) Supplies nutrients to, and removes waste products from, the cartilage cells which have no direct blood supply.
Ligament – fibrous connective tissue that connects bones together.
Tendon – fibrous connective tissue that joins muscle to bone.
Bursa – a small sac or cavity filled with synovial fluid and located at friction points, especially joints. Most bursae are located between tendons and bone.
Frontal plane – divides body into anterior and posterior portions
Sagittal plane – divides the body into right and left sides
Transverse plane – divides the body into superior and inferior portions

G. Terms of Direction

These movements are related to the body as seen in anatomical position.

  1. Flexion, extension
  2. Abduction, adduction
  3. Rotation – inward (medial) rotation; outward (lateral) rotation
  4. Supination, pronation
  5. Elevation, depression
  6. Plantar flexion, dorsiflexion

I. Common Joint Disorders

  1. Sprain
  2. Dislocation
  3. Subluxation
  4. Bursitis
  5. Arthritis

J. Structural Limits To Flexibility

  1.  Bony structure of the joint – can’t be changed by a flexibility program
  2. Ligaments
  3.  Joint capsules
  4. Muscle-tendon unit – muscle and its fascial sheaths – the major focus of
  5. stretching exercises is the elongation of this tissue.

To learn about treatment of first aid emergencies and to recognize sprains, strains and broken bones take a standard first aid course with Vancouver First Aid Ltd. The knowledge learned in a first aid course can help you save a life.