Wrist

wrist joint
A human hand with wrist labeled at left.
Details
Identifiers
Latin	articulatio radio carpea
MeSH	A02.835.583.405.930
TA	A01.1.00.026
FMA	24922
Anatomical terminology [edit on Wikidata]

In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;^[1][2] (2) the wrist joint or radiocarpal joint, the joint between the radius and the carpus;^[2] and (3) the anatomical region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of the metacarpus or five metacarpal bones and the series of joints between these bones, thus referred to as wrist joints.^[3][4] This region also includes the carpal tunnel, the anatomical snuff box, the flexor retinaculum, and the extensor retinaculum.

As a consequence of these various definitions, fractures to the carpal bones are referred to as carpal fractures, while fractures such as distal radius fracture are often considered fractures to the wrist. ^[5]

Function

Movement

The extrinsic hand muscles are located in the forearm where their bellies form the proximal fleshy roundness. When contracted, most of the tendons of these muscles are prevented from standing up like taut bowstrings around the wrist by passing under the flexor retinaculum on the palmar side and the extensor retinaculum on the dorsal side. On the palmar side the carpal bones form the carpal tunnel through which some of the flexor tendons pass in tendon sheaths that enable them to slide back and forth through the narrow passageway (see carpal tunnel syndrome). ^[6]

Starting from the mid-position of the hand, the movements permitted in the wrist proper are (muscles in order of importance):^[7][8]

• Marginal movements: radial deviation (abduction, movement towards the thumb) and ulnar deviation (adduction, movement towards the little finger). These movements take place about a dorsopalmar axis (back to front) at the radiocarpal and midcarpal joints passing through the capitate bone.
  • Radial abduction: extensor carpi radialis longus, abductor pollicis longus, extensor pollicis longus, flexor carpi radialis, flexor pollicis longus
  • Ulnar adduction: extensor carpi ulnaris, flexor carpi ulnaris, extensor digitorum, extensor digiti minimi
• Movements in the plane of the hand: flexion (palmar flexion, tilting towards the palm) and extension (dorsiflexion, tilting towards the back of the hand). These movements take place through a transverse axis passing through the capitate bone. Palmar flexion is the most powerful of these movements because the flexors, especially the finger flexors, are considerably stronger than the extensors.
  • Extension: extensor digitorum, extensor carpi radialis longus, extensor carpi radialis brevis, extensor indicis, extensor pollicis longus, extensor digiti minimi, extensor carpi ulnaris
  • Palmar flexion: flexor digitorum superficialis, flexor digitorum profundus, flexor carpi ulnaris, flexor pollicis longus, flexor carpi radialis, abductor pollicis longus
• Intermediate or combined movements

However, movements at the wrist can not be properly described without including movements in the distal radioulnar joint in which the rotary actions of supination and pronation occur and this joint is therefore normally regarded as part of the wrist. ^[9]

Clinical significance

Wrist pain has a number of causes, including carpal tunnel syndrome and osteoarthritis. Tests such as Phalen's test involve palmarflexion at the wrist.

The hand may be deviated at the wrist in some conditions, such as rheumatoid arthritis.

Ossification of the bones around the wrist is one indicator used in taking a bone age.

The term 'wrist fracture' may be used to refer to fractures of the distal radius.

History

Etymology

The English word "wrist" is etymologically derived from the ancient German word wristiz from which are derived modern German rist ("instep", "wrist") and modern Swedish vrist ("instep", "ankle"). The base writh- and its variants are associated with Old English words "wreath", "wrest", and "writhe". The wr- sound of this base seems originally to have been symbolic of the action of twisting. ^[10]

See also

• Brunelli Procedure, related to instability in the wrist, caused by a torn Scapholunate ligament.
• Knuckle-walking, a kind of quadrupedal locomotion involving wrist bone specialization
• Wristlocks use movement extremes of the wrist for martial applications.

Additional Images

• 
  Wrist joint. Deep dissection. Posterior view.
• 
  Wrist joint. Deep dissection. Posterior view.
• 
  Wrist joint. Deep dissection.Anterior, palmar, view.
• 
  Wrist joint. Deep dissection.Anterior, palmar, view.

Notes

1. Behnke 2006, p. 76. "The wrist contains eight bones, roughly aligned in two rows, known as the carpal bones."
2. Moore 2006, p. 485. "The wrist (carpus), the proximal segment of the hand, is a complex of eight carpal bones. The carpus articulates proximally with the forearm at the wrist joint and distally with the five metacarpals. The joints formed by the carpus include the wrist (radiocarpal joint), intercarpal, carpometacarpal and intermetacarpal joints. Augmenting movement at the wrist joint, the rows of carpals glide on each other [...] "
3. Behnke 2006, p. 77. "With the large number of bones composing the wrist (ulna, radius, eight carpas, and five metacarpals), it makes sense that there are many, many joints that make up the structure known as the wrist."
4. Baratz 1999, p. 391. "The wrist joint is composed of not only the radiocarpal and distal radioulnar joints but also the intercarpal articulations."
5. "Fractures, Wrist". eMedicine, Medscape. Retrieved August 2009. Fractures of the distal radius, ulna, or both account for approximately three quarters of bony injuries of the wrist. Check date values in: |access-date= (help)
6. Saladin, 2003, pp. 361, 365
7. Platzer 2004, p. 132
8. Platzer 2004, p. 172
9. Kingston 2000, pp. 126–127
10. "Hand Etymology". American Society for Surgery of the Hand. Retrieved August 2009. Check date values in: |access-date= (help)

References

• Baratz, Mark; Watson, Anthony D.; Imbriglia, Joseph E. (1999). Orthopaedic surgery: the essentials. Thieme. ISBN 0-86577-779-9.
• Behnke, Robert S. (2006). Kinetic anatomy. Human Kinetics. ISBN 0-7360-5909-1.
• Isenberg, David Alan; Maddison, Peter; Woo, Patricia (2004). Oxford textbook of rheumatology. Oxford University Press. ISBN 0-19-850948-0.
• Kingston, Bernard (2000). Understanding joints: a practical guide to their structure and function. Nelson Thornes. ISBN 0-7487-5399-0.
• Moore, Keith L.; Agur, A. M. R. (2006). Essential clinical anatomy. Lippincott Williams & Wilkins. ISBN 0-7817-6274-X.
• Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. ISBN 3-13-533305-1.
• Saladin, Kenneth S. (2003). Anatomy & Physiology: The Unity of Form and Function (3rd ed.). McGraw-Hill.

External links

• Hand kinesiology at the University of Kansas Medical Center