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Skeletal system

Not medically reviewed · Content last updated · 1 min read ·

This is the date the draft was written, not a medical review date.

The skeletal system comprises the bones, cartilages and joints that form the rigid framework of the body. It supports soft tissues, protects vital organs, provides levers for movement and acts as a mineral store and site of haematopoiesis.

Terminologia Anatomica (Latin): Systema skeletale

Components

The adult skeleton has 206 named bones in two divisions: the axial skeleton (skull, vertebral column, ribs and sternum) and the appendicular skeleton (pectoral and pelvic girdles and the limbs). Bones are classed as long, short, flat, irregular or sesamoid, and are linked by fibrous, cartilaginous or synovial joints.

Function

Bone provides mechanical support, protects the brain, spinal cord and thoracic organs, and transmits muscular force to produce movement. It stores calcium and phosphate, and red marrow produces blood cells.

Clinical correlations

Fractures, osteoporosis, osteoarthritis, osteomyelitis and primary or metastatic bone tumours are common conditions. Bone age and growth plate status are assessed radiographically in children; management of each condition follows local guidelines.

Common exam points

  • Know the 206-bone count and the axial versus appendicular division.
  • Classify bones by shape (long, short, flat, irregular, sesamoid) with an example of each.
  • Distinguish compact from cancellous bone, and red from yellow marrow.
  • Classify joints: fibrous, cartilaginous (primary and secondary), synovial.
  • Long bones ossify from primary and secondary centres; the epiphyseal plate is the growth site.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Federative Committee on Anatomical Terminology (FCAT). Terminologia Anatomica: International Anatomical Terminology. Thieme (1998) — Tier 1 (standards / international bodies)

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