Wrist

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Wrist
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A human showing the wrist in the centre
3D Medical Animation Human Wrist.jpg
The carpal bones, sometimes included in the definition of the wrist
Details
Identifiers
Latin articulatio radiocarpalis
MeSH D014953
TA98 A01.1.00.026
TA2 147
FMA 24922
Anatomical terminology

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, bracelet lines, the flexor retinaculum, and the extensor retinaculum.

Contents

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.

Structure

RightHumanPosteriorDistalRadiusUlnaCarpals.jpg
RightHumanAnteriorDistalRadiusUlnaCarpals.jpg
Posterior and anterior aspects of right human wrist
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Ligaments of wrist. Posterior and anterior views

The distal radioulnar joint (DRUJ) is a pivot joint located between the distal ends of the radius and ulna, which make up the forearm. Formed by the head of the ulna and the ulnar notch of the radius, the DRUJ is separated from the radiocarpal (wrist) joint by an articular disk lying between the radius and the styloid process of the ulna. The capsule of the joint is lax and extends from the inferior sacciform recess to the ulnar shaft. The DRUJ works with the proximal radioulnar joint (at the elbow) for pronation and supination. [5]

The radiocarpal (wrist) joint is an ellipsoid joint formed by the radius and the articular disc proximally and the proximal row of carpal bones distally. The carpal bones on the ulnar side only make intermittent contact with the proximal side — the triquetrum only makes contact during ulnar abduction. The capsule, lax and un-branched, is thin on the dorsal side and can contain synovial folds. The capsule is continuous with the midcarpal joint and strengthened by numerous ligaments, including the palmar and dorsal radiocarpal ligaments, and the ulnar and radial collateral ligaments. [6]

The parts forming the radiocarpal joint are the lower end of the radius and under surface of the articular disk above; and the scaphoid, lunate, and triquetral bones below. The articular surface of the radius and the undersurface of the articular disk form together with a transversely elliptical concave surface, the receiving cavity. The superior articular surfaces of the scaphoid, lunate, and triquetrum form a smooth convex surface, the condyle, which is received into the concavity. [7]

Carpal bones of the hand:

In the hand proper a total of 13 bones form part of the wrist: eight carpal bones — scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, and hamate — and five metacarpal bones —the first, second, third, fourth, and fifth metacarpal bones. [8]

The midcarpal joint is the S-shaped joint space separating the proximal and distal rows of carpal bones. The intercarpal joints, between the bones of each row, are strengthened by the radiate carpal and pisohamate ligaments and the palmar, interosseous, and dorsal intercarpal ligaments. Some degree of mobility is possible between the bones of the proximal row while the bones of the distal row are connected to each other and to the metacarpal bones —at the carpometacarpal joints — by strong ligaments —the pisometacarpal and palmar and dorsal carpometacarpal ligament — that makes a functional entity of these bones. Additionally, the joints between the bases of the metacarpal bones —the intermetacarpal articulations — are strengthened by dorsal, interosseous, and palmar intermetacarpal ligaments. [6]

The earliest carpal bones to ossify are capitate bone and hamate bone in the first six months of an infant life. [9]

Articulations

The radiocarpal, intercarpal, midcarpal, carpometacarpal, and intermetacarpal joints often intercommunicate through a common synovial cavity. [10]

Articular surfaces

It has two articular surfaces named, proximal and distal articular surfaces respectively. The proximal articular surface is made up of the lower end of the radius and a triangular articular disc of the inferior radio-ulnar joint. On the other hand, the distal articular surface is made up of proximal surfaces of the scaphoid, triquetral and lunate bones. [11]

Micro-radiography of 8-weeks human embryo hand Hand of embryo.jpg
Micro-radiography of 8-weeks human embryo hand

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, [12] 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). [13]

Starting from the mid-position of the hand, the movements permitted in the wrist proper are (muscles in order of importance): [14] [15]

Magnetic resonance imaging (MRI) of radial abduction (rightwards in image) and ulnar adduction (leftwards in image)
Magnetic resonance imaging (MRI) of wrist extension and return to neutral position

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. [17]

Clinical significance

Projectional radiograph of a normal wrist (left image) and one with a dorsal tilt due to wrist osteoarthritis (as well as osteoporosis). The angle of the distal surface of the lunate bone is annotated. A dorsal tilt of 10 to 15 degrees is considered normal. X-ray of normal wrist and wrist with dorsally tilted wrist joint.jpg
Projectional radiograph of a normal wrist (left image) and one with a dorsal tilt due to wrist osteoarthritis (as well as osteoporosis). The angle of the distal surface of the lunate bone is annotated. A dorsal tilt of 10 to 15 degrees is considered normal.

Wrist pain has a number of causes, including carpal tunnel syndrome, [16] ganglion cyst, [19] tendinitis, [20] and osteoarthritis. Tests such as Phalen's test involve palmarflexion at the wrist.

The hand may deviate 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.

A wrist fracture usually means a fracture of the distal radius.

History

Etymology

The English word "wrist" is etymologically derived from the Proto-Germanic 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. [21]

See also

Additional images

Related Research Articles

<span class="mw-page-title-main">Carpal bones</span> Eight small bones that make up the wrist (or carpus) that connects the hand to the forearm

The carpal bones are the eight small bones that make up the wrist (carpus) that connects the hand to the forearm. The term "carpus" and "carpal" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the carpal bones is to articulate with the radial and ulnar heads to form a highly mobile condyloid joint, to provide attachments for thenar and hypothenar muscles, and to form part of the rigid carpal tunnel which allows the median nerve and tendons of the anterior forearm muscles to be transmitted to the hand and fingers.

<span class="mw-page-title-main">Anatomical snuffbox</span> Indent on back of hand between tendons

The anatomical snuff box or snuffbox or foveola radialis is a triangular deepening on the radial, dorsal aspect of the hand—at the level of the carpal bones, specifically, the scaphoid and trapezium bones forming the floor. The name originates from the use of this surface for placing and then sniffing powdered tobacco, or "snuff." It is sometimes referred to by its French name tabatière.

<span class="mw-page-title-main">Extensor carpi radialis longus muscle</span>

The extensor carpi radialis longus is one of the five main muscles that control movements at the wrist. This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone.

In human anatomy, extensor carpi radialis brevis is a muscle in the forearm that acts to extend and abduct the wrist. It is shorter and thicker than its namesake extensor carpi radialis longus which can be found above the proximal end of the extensor carpi radialis brevis.

<span class="mw-page-title-main">Trapezium (bone)</span> Bone of the wrist

The trapezium bone is a carpal bone in the hand. It forms the radial border of the carpal tunnel.

<span class="mw-page-title-main">Metacarpal bones</span> Bones of hand

In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones, which articulate with the forearm. The metacarpal bones are homologous to the metatarsal bones in the foot.

<span class="mw-page-title-main">Scaphoid bone</span> Bone of the carpus

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. It forms the radial border of the carpal tunnel. 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 cashew nut.

<span class="mw-page-title-main">Capitate bone</span> Carpal bone in the wrist

The capitate bone is a bone in the human wrist found in the center of the carpal bone region, located at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone and forms the third carpometacarpal joint. The capitate bone is the largest of the carpal bones in the human hand. It presents, above, a rounded portion or head, which is received into the concavity formed by the scaphoid and lunate bones; a constricted portion or neck; and below this, the body. The bone is also found in many other mammals, and is homologous with the "third distal carpal" of reptiles and amphibians.

<span class="mw-page-title-main">Radius (bone)</span> One of the two long bones of the forearm

The radius or radial bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is longer than the radius, but the radius is thicker. The radius is a long bone, prism-shaped and slightly curved longitudinally.

<span class="mw-page-title-main">Upper limb</span> Consists of the arm, forearm, and hand

The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the arm, forearm and hand, and is primarily used for climbing, lifting and manipulating objects.

In human anatomy, the extensor pollicis longus muscle (EPL) is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it partly covers and acts to stretch the thumb together with this muscle.

<span class="mw-page-title-main">Adductor pollicis muscle</span> Muscle in the thenar compartment

In human anatomy, the adductor pollicis muscle is a muscle in the hand that functions to adduct the thumb. It has two heads: transverse and oblique.

<span class="mw-page-title-main">Carpometacarpal joint</span>

The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.

<span class="mw-page-title-main">Palmar radiocarpal ligament</span>

The palmar radiocarpal ligament is a broad membranous band, attached above to the distal end of the radius, and passing downward to the scaphoid, lunate, triquetrum and capitate of the carpal bones in the wrist.

<span class="mw-page-title-main">Intercarpal joints</span> Joints of the carpal bones of the wrist

The intercarpal joints can be subdivided into three sets of joints : Those of the proximal row of carpal bones, those of the distal row of carpal bones, and those of the two rows with each other.

<span class="mw-page-title-main">Midcarpal joint</span>

The midcarpal joint is formed by the scaphoid, lunate, and triquetral bones in the proximal row, and the trapezium, trapezoid, capitate, and hamate bones in the distal row. The distal pole of the scaphoid articulates with two trapezial bones as a gliding type of joint. The proximal end of the scaphoid combines with the lunate and triquetrum to form a deep concavity that articulates with the convexity of the combined capitate and hamate in a form of diarthrodial, almost condyloid joint.

<span class="mw-page-title-main">Carpal tunnel</span> Structure of human wrist

In the human body, the carpal tunnel or carpal canal is a flattened body cavity on the flexor (palmar/volar) side of the wrist, bounded by the carpal bones and flexor retinaculum. It forms the passageway that transmits the median nerve and the tendons of the extrinsic flexor muscles of the hand from the forearm to the hand. There are described cases of the anatomical variant median artery occurrence.

<span class="mw-page-title-main">Extrinsic extensor muscles of the hand</span>

The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand. They include the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor digitorum (ED), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI).

<span class="mw-page-title-main">Wrist osteoarthritis</span> Medical condition

Wrist osteoarthritis is gradual loss of articular cartilage and hypertrophic bone changes (osteophytes). While in many joints this is part of normal aging (senescence), in the wrist osteoarthritis usually occurs over years to decades after scapholunate interosseous ligament rupture or an unhealed fracture of the scaphoid. Characteristic symptoms including pain, deformity and stiffness. Pain intensity and incapability are notably variable and do not correspond with arthritis severity on radiographs.

<span class="mw-page-title-main">Muscles of the thumb</span>

The muscles of the thumb are nine skeletal muscles located in the hand and forearm. The muscles allow for flexion, extension, adduction, abduction and opposition of the thumb. The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in the forearm, and the intrinsic hand muscles, with their muscles bellies located in the hand proper.

References

  1. ↑ Behnke 2006 , p. 76 "The wrist contains eight bones, roughly aligned in two rows, known as the carpal bones."
  2. 1 2 Moore KL, Agur AM (2006). Essential clinical anatomy. Lippincott Williams & Wilkins. p. 485. ISBN   0-7817-6274-X. 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 (the 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 M, Watson AD, Imbriglia JE (1999). Orthopaedic surgery: the essentials. Thieme. p. 391. ISBN   0-86577-779-9. The wrist joint is composed of not only the radiocarpal and distal radioulnar joints but also the intercarpal articulations.
  5. ↑ Platzer 2004 , p. 122
  6. 1 2 Platzer 2004 , p. 130
  7. ↑ "Wrist Joint". The Lecturio Medical Concept Library. Retrieved 2021-06-23.
  8. ↑ Platzer 2004 , pp. 126–129
  9. ↑ Al-Khater KM, Hegazi TM, Al-Thani HF, Al-Muhanna HT, Al-Hamad BW, Alhuraysi SM, et al. (September 2020). "Time of appearance of ossification centers in carpal bones. A radiological retrospective study on Saudi children". Saudi Medical Journal. 41 (9): 938–946. doi:10.15537/smj.2020.9.25348. PMC   7557557 . PMID   32893275.
  10. ↑ Isenberg DA, Maddison P, Woo P (2004). Oxford textbook of rheumatology. Oxford University Press. p. 87. ISBN   0-19-850948-0.
  11. ↑ "Wrist Joint". Earth's Lab.
  12. ↑ Rea P (2016-01-01). "Chapter 3 - Neck". In Rea P (ed.). Essential Clinically Applied Anatomy of the Peripheral Nervous System in the Head and Neck. Academic Press. pp. 131–183. doi:10.1016/b978-0-12-803633-4.00003-x. ISBN   978-0-12-803633-4.
  13. ↑ Saladin KS (2003). Anatomy & Physiology: The Unity of Form and Function (3rd ed.). McGraw-Hill. pp. 361, 365.
  14. ↑ Platzer 2004 , p. 132
  15. ↑ Platzer 2004 , p. 172
  16. 1 2 3 4 5 Lalani I, Argoff CE (2008-01-01). "Chapter 10 - History and Physical Examination of the Pain Patient". In Benzon HT, Rathmell JP, Wu CL, Turk DC (eds.). Raj's Practical Management of Pain (Fourth ed.). Philadelphia: Mosby. pp. 177–188. doi:10.1016/B978-032304184-3.50013-3. ISBN   978-0-323-04184-3.
  17. ↑ Kingston B (2000). Understanding joints: a practical guide to their structure and function. Nelson Thornes. pp. 126–127. ISBN   0-7487-5399-0.
  18. ↑ Döring AC, Overbeek CL, Teunis T, Becker SJ, Ring D (October 2016). "A Slightly Dorsally Tilted Lunate on MRI can be Considered Normal". The Archives of Bone and Joint Surgery. 4 (4): 348–352. PMC   5100451 . PMID   27847848.
  19. ↑ Stretanski MF (2020-01-01). "Chapter 32 - Hand and Wrist Ganglia". In Frontera WR, Silver JK, Rizzo TD (eds.). Essentials of Physical Medicine and Rehabilitation (Fourth ed.). Philadelphia: Content Repository Only!. pp. 169–173. doi:10.1016/B978-0-323-54947-9.00032-8. ISBN   978-0-323-54947-9. S2CID   229189365.
  20. ↑ Waldman SD (2014-01-01). "Chapter 58 - Flexor Carpi Radialis Tendinitis". In Waldman SD (ed.). Atlas of Uncommon Pain Syndromes (Third ed.). Philadelphia: W.B. Saunders. pp. 172–174. doi:10.1016/b978-1-4557-0999-1.00058-7. ISBN   978-1-4557-0999-1.
  21. ↑ "Hand Etymology". American Society for Surgery of the Hand.

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