Scaphoid bone


Scaphoid bone
Bone: scaphoid bone
Carpus.png
Shown is the right hand, palm down (left) and palm up (right).
Proximal: A=Scaphoid, B=Lunate, C=Triquetral, D=Pisiform
Distal: E=Trapezium, F=Trapezoid, G=Capitate, H=Hamate
1= Radius, 2=Ulna, 3=Metacarpals
Gray221.png
The left scaphoid bone
Latin os scaphoideum, os naviculare manus
Gray's subject #54 221
Articulations articulates with five bones
radius proximally
trapezoid bone and trapezium bone distally
capitate and lunate medially  
MeSH Scaphoid+Bone

The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb-side of the wrist (also called the lateral or radial side). The scaphoid bone is the largest bone of the proximal row of wrist bones, its long axis being from above downward, lateralward, and forward. It is approximately the size and shape of a medium sized cashew.

Contents

Gallery


Etymology

The etymology of the scaphoid bone is derived from the Greek skaphe which means "a boat," and the Greek eidos which means "form".[1] This refers to the shape of the bone, supposedly reminiscent of a boat, and in older literature on human anatomy[2] the scaphoid is referred to as the navicular bone of the hand, since there is also a bone in a similar position in the foot, called the navicular. In reptiles, birds, and amphibians, this bone is instead commonly referred to as the radiale, because of its articulation with the radius.

Surfaces

The superior surface is convex, smooth, of triangular shape, and articulates with the lower end of the radius.

The inferior surface, directed downward, backward and laterally is also smooth, convex, and triangular, and is divided by a slight ridge into two parts, the lateral articulating with the greater multangular, the medial with the lesser multangular.

On the dorsal surface is a narrow, rough groove, which runs the entire length of the bone, and serves for the attachment of ligaments.

The volar surface is concave above, and elevated at its lower and lateral part into a rounded projection, the tubercle, which is directed forward and gives attachment to the transverse carpal ligament and sometimes origin to a few fibers of the Abductor pollicis brevis.

The lateral surface is rough and narrow, and gives attachment to the radial collateral ligament of the wrist.

The medial surface presents two articular facets; of these, the superior or smaller is flattened of semilunar form, and articulates with the lunate bone; the inferior or larger is concave, forming with the lunate a concavity for the head of the capitate bone.

The distal convex surface articulates with trapezium and trapezoid.[2]

Clinical significance

Scaphoid fracture before and after operation

The scaphoid can be slow to heal because of the limited circulation to the bone. It receives its blood supply primarily from lateral and distal branches of the radial artery. Fortunately, it is relatively difficult to break, but is the most commonly fractured bone in the carpus, particularly because of its unique anatomy and position within the wrist. Approximately 60% of carpal fractures are scaphoid fractures.

The scaphoid primarily receives its blood from the distal end. Failure to heal of the fracture ( non union ) will lead to post traumatic osteoarthritis of the carpus. Healing of the fracture with a non anatomic deformity ( frequently a volar flexed "humpback" ) can also lead to post traumatic arthritis . Non unions can result in loss of blood supply to the proximal pole which can result in avascular necrosis of the proximal segment.


A condition called scapholunate instability can occur when the scapholunate ligament (connecting the scaphoid to the lunate bone) and other surrounding ligaments are disrupted.

Fractures of the scaphoid must be recognized and treated quickly, as prompt treatment by immobilization or surgical fixation increases the likelihood of healing in anatomic alignment avoiding mal union or non union. Delays may compromise healing. Even rapidly immobilized fractures may require surgical treatment, including use of a headless compression screw such as the Herbert screw to bind the two halves together.

Palpation

The scaphoid can be palpated at the base of the anatomical snuff box. It can also be palpated in the volar (palmar) hand/wrist. Its position is the intersections of the long axes of the four fingers while in a fist, or the base of the thenar eminence. When felt in this position, the bone will feel to slide forward during radial deviation (wrist abduction), and flexion.

Clicking of the scaphoid, or no anterior translation can indicate scapholunate instability.

See also

References

  1. ^ Mosby’s Medical, Nursing and Allied Health Dictionary, Fourth Edition, Mosby-Year Book 1994, p. 1396
  2. ^ a b "Gray's Anatomy, 6b. The Hand. 1. The Carpus. 4". 1918. http://www.bartleby.com/107/54.html. Retrieved December 2009. 

External links


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Look at other dictionaries:

  • Scaphoid bone — Scaphoid Scaph oid (?; 277), a. [Gr. ska fh a boat + oid: cf. F. scapho[ i]de.] (Anat.) Resembling a boat in form; boat shaped. n. The scaphoid bone. [1913 Webster] {Scaphoid bone} (a) One of the carpal bones, which articulates with the radius;… …   The Collaborative International Dictionary of English

  • scaphoid bone — n SCAPHOID * * * a boat shaped bone of the wrist (see carpus). It articulates with the trapezium and trapezoid bones in front, with the radius behind, and with the capitate and lunate medially. It is commonly injured by falls on the wrist. * * *… …   Medical dictionary

  • scaphoid bone — noun (anatomy) One of the carpal bones of the wrist. Syn: navicular bone, scaphoid …   Wiktionary

  • scaphoid bone — noun the largest wrist bone on the thumb side • Syn: ↑os scaphoideum, ↑navicular • Derivationally related forms: ↑navicular (for: ↑navicular) • Hypernyms: ↑ …   Useful english dictionary

  • scaphoid bone — a boat shaped bone of the wrist (see carpus). It articulates with the trapezium and trapezoid bones in front, with the radius behind, and with the capitate and lunate medially. It is commonly injured by falls on the wrist …   The new mediacal dictionary

  • scaphoid bone of foot — os naviculare …   Medical dictionary

  • scaphoid bone of hand — os scaphoideum …   Medical dictionary

  • Кость Ладьевидная (Scaphoid Bone) — напоминающая по внешнему виду ладью кость запястья. Внизу ладьевидная кость сочленяется с костью трапецией, головчатой и трапециевидной костями, вверху с лучевой, сбоку с полулунной костью. Эта кость чаще всего травмируется при опоре во время… …   Медицинские термины

  • tubercle of scaphoid bone — tuberculum ossis scaphoidei …   Medical dictionary

  • Scaphoid — Scaph oid (?; 277), a. [Gr. ska fh a boat + oid: cf. F. scapho[ i]de.] (Anat.) Resembling a boat in form; boat shaped. n. The scaphoid bone. [1913 Webster] {Scaphoid bone} (a) One of the carpal bones, which articulates with the radius; the… …   The Collaborative International Dictionary of English


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