Assistant
Definition
By Gregory R. Waryasz, MD
The pisiform of the musculoskeletal system is characterized by being a pea shaped sesamoid bone.
It is part of the upper limb. The pisiform articulates with the triquetrum. It consists of bone and cartilage tissue once mature.
Its unique structural features include its being shaped like a small pea. It helps to form the medial border of the tunnel of Guyon where the ulnar nerve and artery are located. It is located within the flexor carpi ulnaris tendon.
The dorsal surface has a smooth oval shaped facet to articulate with the triquetrum.
The volar surface is rough and allows for attachment of the transverse carpal ligament, flexor carpi ulnaris, and the abductor digiti quinti.
The pisiform ossifies at age 9. The pisiform as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.
The function of the pisiform is to articulate with the triquetrum.
Common diseases of the pisiform include fracture and arthritis.
Fracture of the pisiform generally results from direct trauma.
Arthritis is a condition of bone formation and joint space narrowing that can lead to pain and decreased range of motion.
Commonly used diagnostic procedures include clinical history, physical exam, x-ray, MRI, bone scan, and CT scan.
It is usually treated with non-operative treatment for fractures.
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.