Epiphysis

An epiphysis (from Ancient Greek ἐπί (epí) 'on top of' and φύσις (phúsis) 'growth'; pl.: epiphyses) is one of the rounded ends or tips of a long bone that ossify from one or more secondary centers of ossification. Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate). During formation of the secondary ossification center, vascular canals (epiphysial canals) stemming from the perichondrium invade the epiphysis, supplying nutrients to the developing secondary centers of ossification. At the joint, the epiphysis is covered with articular cartilage; below that covering is a zone similar to the epiphyseal plate, known as subchondral bone. The epiphysis is found only in mammals which means it is a mammalian synapomorphy. However, the secondary center of ossification may have evolved multiple times, having been found in the Jurassic sphenodont Sapheosaurus as well as in the therapsid Niassodon mfumukasi.

Epiphysis
Structure of a long bone, with epiphysis labeled at top and bottom.
Details
Pronunciation	/ɛˈpɪfɪsɪs/
Part of	Long bones
Identifiers
MeSH	D004838
TA98	A02.0.00.018
TA2	393
FMA	24012
Anatomical terminology [edit on Wikidata]

The epiphysis is filled with red bone marrow, which produces erythrocytes (red blood cells).

Structure

There are four types of epiphyses:

1. Pressure epiphysis: The region of the long bone that forms the joint is a pressure epiphysis (e.g. the head of the femur, part of the hip joint complex). Pressure epiphyses assist in transmitting the weight of the human body and are the regions of the bone that are under pressure during movement or locomotion. Another example of a pressure epiphysis is the head of the humerus which is part of the shoulder complex. Condyles of femur and tibia also come under the pressure epiphysis.
2. Traction epiphysis: The regions of the long bone which are non-articular, i.e. not involved in joint formation. Unlike pressure epiphyses, these regions do not assist in weight transmission. However, their proximity to the pressure epiphysis region means that the supporting ligaments and tendons attach to these areas of the bone. Traction epiphyses ossify later than pressure epiphyses. Examples of traction epiphyses are tubercles of the humerus (greater tubercle and lesser tubercle), and trochanters of the femur (greater and lesser).
3. Atavistic epiphysis: A bone that is independent phylogenetically but is fused with another bone in humans. These types of fused bones are called atavistic, e.g., the coracoid process of the scapula, which has been fused in humans, but is separate in four-legged animals. os trigonum (posterior tubercle of talus) is another example for atavistic epiphysis.
4. Aberrant epiphysis: These epiphyses are deviations from the norm and are not always present. For example, the epiphysis at the head of the first metacarpal bone and at the base of other metacarpal bones

Bones with an epiphysis

There are many bones that contain an epiphysis:

1. Humerus: Located between the shoulder and the elbow.
2. Radius: One of two bones located between the in the forelimb below the elbow. In anatomical position, the radius is lateral to the ulna.
3. Ulna: One of two bones located between the in the forelimb below the elbow. In anatomical position, the ulna is medial to the radius.
4. Metacarpal: Bones of the forelimb. They are distal to the wrist bones, proximal to the phalanges of the forelimb.
5. Phalanges: Bones that are nearest the end of the limbs.
6. Femur: Located between the hip and the knee. Forms the upper half of the knee joint. (The longest human bone.)
7. Fibula: One of two bones in the lower leg. Forms part of the lower half of the knee joint. Part oIt is lateral to the tibia and smaller.
8. Tibia: One of two bones in the lower leg. Forms part of the lower half of the knee joint. It is medial to the fibula and does most of the weight bearing.
9. Metatarsal: Bones near the distal end of the hindlimb, and proximal to the phalanges for the other four.

Pseudo-epiphysis

It is common in children to have a pseudo-epiphysis of the first metatarsal.

A pseudo-epiphysis is an epiphysis-looking end of a bone where an epiphysis is not normally located. A pseudo-epiphysis is delineated by a transverse notch, looking similar to a growth plate. However, these transverse notches lack the typical cell columns found in normal growth plates, and do not contribute significantly to longitudinal bone growth. Pseudo-epiphyses are found at the distal end of the first metacarpal bone in 80% of the normal population, and at the proximal end of the second metacarpal in 60%.

Clinical significance

Pathologies of the epiphysis include avascular necrosis and osteochondritis dissecans (OCD). OCD involves the subchondral bone.

Epiphyseal lesions include chondroblastoma and giant-cell tumor.

Additional images

• Long bone
• Longitudinal section of head of left humerus.

References

1. OED 2nd edition, 1989 as /εˈpɪfɪsɪs/.
2. Entry "epiphysis" in Merriam-Webster Online Dictionary.
3. Chaurasia, B. D. (2009). B D Chaurasia's Handbook of General Anatomy (4th ed.). Delhi, India: CBS. p. 41. ISBN 978-8123916545. OCLC 696622496.
4. "Epiphysis | Definition, Anatomy, & Function". www.britannica.com. Retrieved 2023-01-28.
5. Xie, Meng; Chagin, Andrei S. (January 2021). "The epiphyseal secondary ossification center: Evolution, development and function". Bone. 142: 115701. doi:10.1016/j.bone.2020.115701. PMID 33091640.
6. Estefa, Jordi; Tafforeau, Paul; Clement, Alice M; Klembara, Jozef; Niedźwiedzki, Grzegorz; Berruyer, Camille; Sanchez, Sophie (2021-03-02). Tautz, Diethard; Blumer, Michael; Woodward, Holly (eds.). "New light shed on the early evolution of limb-bone growth plate and bone marrow". eLife. 10: e51581. doi:10.7554/eLife.51581. ISSN 2050-084X. PMC 7924947. PMID 33648627.
7. Xie, Meng; Chagin, Andrei S. (January 2021). "The epiphyseal secondary ossification center: Evolution, development and function". Bone. 142: 115701. doi:10.1016/j.bone.2020.115701. PMID 33091640.
8. Castanhinha, Rui; Araújo, Ricardo; Júnior, Luís C.; Angielczyk, Kenneth D.; Martins, Gabriel G.; Martins, Rui M. S.; Chaouiya, Claudine; Beckmann, Felix; Wilde, Fabian (2013-12-04). "Bringing Dicynodonts Back to Life: Paleobiology and Anatomy of a New Emydopoid Genus from the Upper Permian of Mozambique". PLOS ONE. 8 (12): e80974. doi:10.1371/journal.pone.0080974. ISSN 1932-6203. PMC 3852158. PMID 24324653.
9. Mathis, SK; Frame, BA; Smith, CE (1989). "Distal first metatarsal epiphysis. A common pediatric variant". Journal of the American Podiatric Medical Association. 79 (8): 375–379. doi:10.7547/87507315-79-8-375. ISSN 8750-7315. PMID 2681682.
10. Page 163 in: Giuseppe Guglielmi, Cornelis Van Kuijk (2001). Fundamentals of Hand and Wrist Imaging. Springer Science & Business Media. ISBN 9783540678540.
11. Ogden, J.A.; Ganey, T.M.; Light, T.R.; Belsole, R.J.; Greene, T.L. (1994). "Ossification and pseudoepiphysis formation in the ?nonepiphyseal? end of bones of the hands and feet". Skeletal Radiology. 23 (1): 3–13. doi:10.1007/BF00203694. ISSN 0364-2348. PMID 8160033. S2CID 12682490.
12. "Introductory Course". Archived from the original on 2009-03-06. Retrieved 2009-03-12.

External Link:

• Jurnal Biosains Pascasarjana. Originally Universitas Airlangga Bioscience Master Degree Journal Vol 19 No: 01. Released on 1st April 2017.