Anatomy of Immature Bone | Anatomy of Joints

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Previously we discussed basics of orthopedics, in this part, we will discuss quickly on Anatomy of an Immature long bone and Anatomy of Joints.

Anatomy of Immature Long Bone

A bone consists of four parts: Epiphysis, Growth plate in between epiphysis and metaphysis, Metaphysis and Diaphysis. We will discuss in detail the following:

Functional Classification of Epiphysis

Pressure Epiphysis

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It is an intra-articular weight bearing epiphysis

Traction Epiphysis

It is an extra-articular epiphysis for Traction or Pull or Attachment to soft tissues, mainly tendons

Atavistic Epiphysis

E.g. – Coracoid process of scapula

Aberrant Epiphysis

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Occasional epiphysis, e.g. – Head of first metacarpal

Layers of Growth plate (Physis)

The mnemonic for layers of Growth plate or Physis is as follows:

Real People Have Carrier Options

  1. Reserve Zone / Resting Zone- contains chondrocytes that store glycogen or lipids
  2. Proliferative Zone- determines height and width of bone
  3. Hypertrophic Zone / Maturation Zone
  4. Zone of Calcification
  5. Zone of Ossification

Key points to remember

Reserve zone
  • Gaucher’s disease
Proliferative zone
  • Achondroplasia (dwarfism)
  • Gigantism
  • Laron’s syndrome- Hereditary dwarfism and Truncal obesity
Hypertrophic zone
  • Cartilage converted to bone
  • Maturation occurs with Calcium incorporation
  • Most common layer for trauma or injury
Zone of Calcification
  • Rickets
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Zone of Ossification
  • Vascularity (metaphyseal vascular invasion)


  • Special bone- Spongy, Soft or Cancellous
  • Highly vascular
  • Vessels dilated, Tortuous and End arteries
  • Hair pin loop of vessels
  • Most common site for acute hematogenous osteomyelitis

Anatomy of Joint

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Functional classification of Joint:

  1. Fibrous joint- Synarthrosis- Non-motile
  2. Cartilaginous joint- Amphiarthrosis- Somewhat motile
  3. Synovial joint- Diarthrosis- Highly motile
Feature Fibrous Joint Cartilaginous Joint Synovial joint
Other name Synarthrosis Amphiarthrosis Diarthrosis
Types Suture

E.g. – Cranial vault skull


E.g. – Inferior tibio-fibular joint


E.g. – Tooth and socket joint

1st degree- Synchondrosis or Syncedrosis

E.g. – Costochondral joint

2nd degree- Symphysis

E.g. – Pubic symphysis

Hinge joint

E.g. – Elbow joint

Ellipsoid joint

E.g. – Wrist joint

Condylar joint

E.g. – Knee joint and temporomandibular joint

Ball and socket joint

E.g. – Hip and shoulder joint

Pivot joint

E.g. – Atlantoaxial joint

Saddle joint

E.g. – 1st carpo-metacarpal joint

Gliding joint

E.g. – Inter-carpal joint

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