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Definition
By: Gregory R. Waryasz, MD
The phalanges of the hand are characterized by being 14 total bones.
They are part of the bones of the hand. They consist of bone and cartilage.
The unique structural feature is that each phalanx is made up of two to three bones. The first phalanx is made up of proximal and distal bones. The second through fifth phalanges are made up of proximal, middle, and distal bones. Each phalanx has a base, shaft, and head.
The bones of the 1st phalanx are short, broad, and strong. The proximal 1st phalanx articulates with the 1st metacarpal and the distal 1st phalanx.
The proximal 2nd phalanx articulates with the 2nd metacarpal and the middle 2nd phalanx. The middle 2nd phalanx articulates with the distal and proximal 2nd phalanx. The distal 2nd phalanx articulates with the middle 2nd phalanx.
The proximal 3rd phalanx articulates with the 3rd metacarpal and the middle 3rd phalanx. The middle 3rd phalanx articulates with the distal and proximal 3rd phalanx. The distal 3rd phalanx articulates with the middle 3rd phalanx.
The proximal 4th phalanx articulates with the 4th metacarpal and the middle 4th phalanx. The middle 4th phalanx articulates with the distal and proximal 4th phalanx. The distal 4th phalanx articulates with the middle 4th phalanx.
The proximal 5th phalanx articulates with the 5th metacarpal and the middle 5th phalanx. The middle 5th phalanx articulates with the distal and proximal 5th phalanx. The distal 5th phalanx articulates with the middle 5th phalanx.
The phalanges all have secondary ossification centers at the bases that appear during the 3rd year proximally, 4th year middle, and the 5th year distally. The phalanges as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.
The function of the phalanges is to help grip objects and perform all types of motor tasks.
Common diseases include arthritis, fracture, tumor, amniotic band syndrome, and osteomyelitis.
Arthritis can occur as a result of aging and use (osteoarthritis), rheumatoid arthritis, or as a result of post-traumatic changes.
Amniotic band syndrome occurs when amniotic bands/tissue in utero traps developing parts of a fetus. Toes can be amputated or deformed by this process.
Polydactyly refers to the presence of more than 5 fingers. Brachydactyly is the term for short digits. Arachnodactyly refers to excessively long digits. Syndactyly is the term for when there is fusion of digits together. Acrosyndactyly occurs when there is a webbing of tissue that joins more than 1 finger together.
Osteomyelitis is an infection of the bone typically due to bacteria.
Commonly used diagnostic procedures include clinical history, physical exam, plain radiographs, CT scan, bone scan, and MRI.
It is usually treated with either non-operative methods or operative methods. Fractures can be treated non-operatively or operatively. Arthritis can be treated with surgery, physical therapy, or NSAIDs. Tumors can be treated with chemotherapy, radiation, and/or surgery depending upon the type. Osteomyelitis is treated with surgery and antibiotics. Polydactyly can be treated with surgical removal of any extra fingers or tissue.
References
Elstrom J, Virkus W, Pankovich (eds), Handbook of Fractures (3rd edition), McGraw Hill, New York, NY, 2006.
Koval K, Zuckerman J (eds), Handbook of Fractures (3rd edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.
Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Wheeless’ Textbook of Orthopaedics: Phalangeal Injury (http://www.wheelessonline.com/ortho/phalangeal_injury)
The Normal Phalanges |
| 45737d05 hand wrist phalanx phalanges normal anatomy head body shaft base mcp dip pip thumb index middle ring pinky proximal interphalangeal distal interphalangeal metacarpophalangeall joint proximal phalanx middle phalanx distal phalanx normal anatomy plain film X-ray Courtesy Ashley Davidoff MD 45737 45738 45739 45741 |
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The Joints |
| 45737d04 bone hand wrist phalanx phalanges head body shaft base mcp dip pip thumb index middle ring pinky proximal interphalangeal distal interphalangeal metacarpophalangeall joint proximal phalanx middle phalanx distal phalanx normal anatomy plain film Courtesy Ashley Davidoff MD 45737 45738 45739 45741 |
