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;
[ "The wrist contains eight bones, roughly aligned in two rows, known as the carpal bones."] (2) the wrist joint or radiocarpal joint, the joint between the
radius
In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...
and the
carpus 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''.
[ "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."] This region also includes the
carpal tunnel
In the human body, the carpal tunnel or carpal canal is the passageway on the palmar side of the wrist that connects the forearm to the hand.
The tunnel is bounded by the bones of the wrist and flexor retinaculum from connective tissue. Normall ...
, the
anatomical snuff box, bracelet lines, 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.
Structure
The
distal radioulnar joint is a pivot joint located between the bones of the
forearm
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in ...
, the
radius
In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...
and
ulna. Formed by the
head of the ulna and the
ulnar notch of the radius, this joint is separated from the radiocarpal joint by an articular disk lying between the radius and the
styloid process of the ulna
The styloid process of the ulna is a bony prominence found at distal end of the ulna in the forearm.
Structure
The styloid process of the ulna projects from the medial and back part of the ulna. It descends a little lower than the head. The head ...
. The capsule of the joint is lax and extends from the
inferior sacciform recess to the ulnar shaft. Together with the
proximal radioulnar joint
The proximal radioulnar articulation, also known as the proximal radioulnar joint (PRUJ), is a synovial pivot joint between the circumference of the head of the radius and the ring formed by the radial notch of the ulna and the annular ligament ...
, the distal radioulnar joint permits
pronation and
supination.
The radiocarpal joint or 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
ligament
A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the:
* Peritoneal l ...
s, including the
palmar and
dorsal radiocarpal ligaments, and the
ulnar and
radial collateral ligaments.
The parts forming the radiocarpal joint are the lower end of the
radius
In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...
and under surface of the
articular disk above; and the
scaphoid,
lunate
Lunate is a crescent or moon-shaped microlith. In the specialized terminology of lithic reduction, a lunate flake is a small, crescent-shaped flake removed from a stone tool during the process of pressure flaking.
In the Natufian period, a lu ...
, 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.
Carpal bones of the
hand:
* ''Proximal:'' A=
Scaphoid, B=
Lunate
Lunate is a crescent or moon-shaped microlith. In the specialized terminology of lithic reduction, a lunate flake is a small, crescent-shaped flake removed from a stone tool during the process of pressure flaking.
In the Natufian period, a lu ...
, C=
Triquetrum, D=
Pisiform
The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisifomis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel.
Structure
The pisiform is a sesamoid bone, ...
* ''Distal:'' E=
Trapezium, F=
Trapezoid, G=
Capitate, H=
Hamate
In the hand proper a total of 13 bones form part of the wrist: eight
carpal bones—
scaphoid,
lunate
Lunate is a crescent or moon-shaped microlith. In the specialized terminology of lithic reduction, a lunate flake is a small, crescent-shaped flake removed from a stone tool during the process of pressure flaking.
In the Natufian period, a lu ...
,
triquetral,
pisiform
The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisifomis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel.
Structure
The pisiform is a sesamoid bone, ...
,
trapezium,
trapezoid,
capitate, and
hamate— and five
metacarpal bones—the
first,
second
The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ea ...
,
third
Third or 3rd may refer to:
Numbers
* 3rd, the ordinal form of the cardinal number 3
* , a fraction of one third
* 1⁄60 of a ''second'', or 1⁄3600 of a ''minute''
Places
* 3rd Street (disambiguation)
* Third Avenue (disambiguation)
* Hi ...
,
fourth, and
fifth metacarpal bones.
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.
The earliest carpal bones to ossify are
capitate bone and
hamate bone in the first six months of an infant life.
Articulations
The radiocarpal, intercarpal, midcarpal, carpometacarpal, and intermetacarpal joints often intercommunicate through a common synovial cavity.
[
]
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.
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
In the human body, the carpal tunnel or carpal canal is the passageway on the palmar side of the wrist that connects the forearm to the hand.
The tunnel is bounded by the bones of the wrist and flexor retinaculum from connective tissue. Normall ...
, 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
Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic compression of the median nerve as it travels through the wrist at the carpal tunn ...
).
Starting from the mid-position of the hand, the
movements permitted in the wrist proper are (muscles in order of importance):
* 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 (up to 20°):
extensor carpi radialis longus
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each ...
,
abductor pollicis longus,
extensor pollicis longus
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 ...
,
flexor carpi radialis,
flexor pollicis longus
The flexor pollicis longus (; FPL, Latin ''flexor'', bender; ''pollicis'', of the thumb; ''longus'', long) is a muscle in the forearm and hand that flexes the thumb. It lies in the same plane as the flexor digitorum profundus. This muscle is un ...
** Ulnar adduction (up to 30°):
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 (up to 60°):
extensor digitorum,
extensor carpi radialis longus
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each ...
,
extensor carpi radialis brevis,
extensor indicis
In human anatomy, the extensor indicis roprius'' is a narrow, elongated skeletal muscle in the deep layer of the dorsal forearm, placed medial to, and parallel with, the extensor pollicis longus. Its tendon goes to the index finger, which it exte ...
,
extensor pollicis longus
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 ...
,
extensor digiti minimi,
extensor carpi ulnaris
* Palmar flexion (up to 70°):
flexor digitorum superficialis
Flexor digitorum superficialis (''flexor digitorum sublimis'') is an extrinsic flexor muscle of the fingers at the proximal interphalangeal joints.
It is in the anterior compartment of the forearm. It is sometimes considered to be the deepest p ...
,
flexor digitorum profundus
The flexor digitorum profundus is a muscle in the forearm of humans that flexes the fingers (also known as digits). It is considered an extrinsic hand muscle because it acts on the hand while its muscle belly is located in the forearm.
Togeth ...
,
flexor carpi ulnaris,
flexor pollicis longus
The flexor pollicis longus (; FPL, Latin ''flexor'', bender; ''pollicis'', of the thumb; ''longus'', long) is a muscle in the forearm and hand that flexes the thumb. It lies in the same plane as the flexor digitorum profundus. This muscle is un ...
,
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.
Clinical significance
Wrist pain 300px, An illustration of wrist pain
Wrist pain or open wrist is a type of syndrome that prevents the patient using their hand due to a painful wrist. The pain may be sharp, sometimes steadily increasing after trying to apply force. Typically pain ...
has a number of causes, including
carpal tunnel syndrome
Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic compression of the median nerve as it travels through the wrist at the carpal tunn ...
,
ganglion cyst,
tendinitis,
and
osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the ...
. Tests such as
Phalen's test
Phalen's maneuver is a diagnostic test for carpal tunnel syndrome by an American orthopedist named George S. Phalen.
Technique
The patient is asked to hold their wrists in complete and forced flexion (pushing the dorsal surfaces of both hand ...
involve
palmarflexion at the wrist.
The hand may deviate at the wrist in some conditions, such as
rheumatoid arthritis
Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are inv ...
.
Ossification
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in ...
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
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 usually slightly longer than ...
.
History
Etymology
The
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ...
word "
wrist" is
etymologically derived from the ancient
German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ge ...
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
Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th ...
words "
wreath", "
wrest", and "
writhe
In knot theory, there are several competing notions of the quantity writhe, or \operatorname. In one sense, it is purely a property of an oriented link diagram and assumes integer values. In another sense, it is a quantity that describes the amoun ...
". The ''wr-'' sound of this base seems originally to have been symbolic of the action of twisting.
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.
*
Glossary of bowling § Wrist, a measure of wrist position in bowling ball deliveries
Additional images
File:Dissection of the human hand - 02.jpg, Wrist joint. Deep dissection. Posterior view.
File:Slide5kaka.JPG, Wrist joint. Deep dissection. Posterior view.
File:Slide2dsds.JPG, Wrist joint. Deep dissection.Anterior, palmar, view.
File:Slide3dsds.JPG, Wrist joint. Deep dissection.Anterior, palmar, view.
References
Sources
*
*
External links
*
{{Authority control
*Wrist
Upper limb anatomy