Musculoskeletal System - Bone Development Timeline

From Embryology

Introduction

The adult human skeleton has about 206 different bones which are formed from fusion of significantly more bones in the postnatal developing neonate and child (about 275). Two main forms of ossification occur in different bones, intramembranous (eg skull) and endochondral (eg vertebra) ossification. Ossification in general continues postnatally, through puberty until mid 20s.

Axial skeleton.jpg

Axial skeleton

(80 bones in skull, vertebra, ribs, sternum)

Appendicular skeleton developmental regions.jpg

Appendicular skeleton

(126 bones in limbs, shoulders, pelvis)

Endochondral ossification within the limb begins at Carnegie stage 18 and also occurs throughout embryo skeleton. This process is the replacement of a cartilage "template" with bone (week 5-12) that continues through postnatal development, with a second surge of growth at puberty.

These notes summarise the timecourse of development of some of these bones in humans.

Musculoskeletal Links: Introduction | mesoderm | somitogenesis | limb | cartilage | bone | bone timeline | bone marrow | shoulder | pelvis | axial skeleton | skull | joint | skeletal muscle | muscle timeline | tendon | diaphragm | Lecture - Musculoskeletal | Lecture Movie | musculoskeletal abnormalities | limb abnormalities | developmental hip dysplasia | cartilage histology | bone histology | Skeletal Muscle Histology | Category:Musculoskeletal
Historic Embryology - Musculoskeletal  
1853 Bone | 1885 Sphenoid | 1902 - Pubo-femoral Region | Spinal Column and Back | Body Segmentation | Cranium | Body Wall, Ribs, and Sternum | Limbs | 1901 - Limbs | 1902 - Arm Development | 1906 Human Embryo Ossification | 1906 Lower limb Nerves and Muscle | 1907 - Muscular System | Skeleton and Limbs | 1908 Vertebra | 1908 Cervical Vertebra | 1909 Mandible | 1910 - Skeleton and Connective Tissues | Muscular System | Coelom and Diaphragm | 1913 Clavicle | 1920 Clavicle | 1921 - External body form | Connective tissues and skeletal | Muscular | Diaphragm | 1929 Rat Somite | 1932 Pelvis | 1940 Synovial Joints | 1943 Human Embryonic, Fetal and Circumnatal Skeleton | 1947 Joints | 1949 Cartilage and Bone | 1957 Chondrification Hands and Feet | 1968 Knee

Some Recent Findings

  • An image-based skeletal tissue model for the ICRP reference newborn[1] "Active marrow distributions were found to be in reasonable agreement with those given previously by the ICRP. However, significant differences were seen in total skeletal and site-specific masses of trabecular and cortical bone between the current and ICRP newborn skeletal tissue models. The latter utilizes an age-independent ratio of 80%/20% cortical and trabecular bone for the reference newborn. In the current study, a ratio closer to 40%/60% is used based upon newborn CT and micro-CT skeletal image analyses. These changes in mineral bone composition may have significant dosimetric implications when considering localized marrow dosimetry for radionuclides that target mineral bone in the newborn child."

Ossification Stages

The process of ossification as determined postnatally clinically has been divided into a series of stages.[2]

  • Stage 1 - non-ossified epiphysis
  • Stage 2 - discernible ossification centre
  • Stage 3 - partial fusion
  • Stage 4 - total fusion
  • Stage 5 - an additional stage recently added is the disappearance of the epiphyseal scar after total fusion.

Clavicle Ossification

The following identifies the process of ossification of the medial clavicular epiphyseal cartilage.[3]

  • Stage 3 - 16 years
  • Stage 4 - 20 years (women), 21 years (men)
  • Stage 5 - 26 years

Long Bone Ossification

Bone-femur-c.jpg

Humerus

Appearance and fusion of bone secondary ossification centres, proximal is closer to body and distal is further away from the body.

Appearance

  • Proximal epiphysis gestation week 36 - 4 years
  • Distal epiphysis 6 months - 10 years

Fusion

  • Proximal epiphysis 12 - 20 years
  • Distal epiphysis 11 - 19 years

Femur

Appearance

  • Proximal epiphysis 1 - 12 years
  • Distal epiphysis Gestation week 36 - 40

Fusion

  • Proximal epiphysis 11 - 19 years
  • Distal epiphysis 14 - 19 years

Data from reference Table 1.[4]

Historic Data

Keibel Mall Table-Skeleton 4.jpg

Upper Limb Ossification Table - Part 1

Keibel Mall Table-Skeleton 5.jpg

Upper Limb Ossification Table - Part 2

Manual of Human Embryology by Franz Keibel and Franklin P. Mall (1910) Chapter XI. Development of the Skeleton and of the Connective Tissues

Hip

  • Triradiate cartilage 14 - 16 years.
    • Y-shaped growth plate region within the developing hip seen in childhood x-rays.


Links: Musculoskeletal System - Abnormalities

Mandible Ossification

Prenatal

Week 6 - Intramembranous ossification center develops lateral to Meckel's cartilage.

Week 7 - Coronoid process begins differentiating.

Week 8 - Coronoid process fuses with main mandibular mass.

Week 10 (approx) - Both condylar and coronoid processes are recognizable and anterior portion of Meckel's cartilage begins to ossify.

Weeks 12-14 - Secondary cartilages for the condyle, coronoid, and symphysis appear.

Weeks 14-16 - Deciduous tooth germs start to form.

Birth

At birth mandible still has separate right and left halves.

Postnatal

Year 1 - Fusion of right and left halves of mandible at the symphysis.

Infancy and childhood - Increase in both size and shape of the mandible; eruption and replacement of teeth.

Year 12-14 - All permanent teeth emerged except third molars.

Data from reference[4] Table 4.

References

  1. <pubmed>19556686</pubmed>
  2. <pubmed>14534796</pubmed>
  3. <pubmed>14534796</pubmed>
  4. 4.0 4.1 <pubmed>12866701</pubmed>


Online Textbooks

Reviews

<pubmed>19092089</pubmed> <pubmed>18279783</pubmed>


Articles

<pubmed>14152896</pubmed>

Search PubMed

  • Bone Development

Search Pubmed: Human Bone Development Timeline | Human Bone Development

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Terms

  • growth recovery lines (growth arrest lines, Harris lines, Parks lines) - lines visible on x-ray images of increased bone density that represent the position of the growth plate at the time of insult to the organism and formed on long bones due to growth arrest. Insults can include juvenile malnutrition, disease or trauma.

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Cite this page: Hill, M.A. (2024, March 28) Embryology Musculoskeletal System - Bone Development Timeline. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Musculoskeletal_System_-_Bone_Development_Timeline

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G