Carpometacarpal joint

Carpometacarpal joint
Carpometacarpal joint
	Ligaments of wrist. Posterior view.
Details
Identifiers
Latin	articulationes carpometacarpeae
MeSH	D052737
TA98	A03.5.11.301
TA2	1827
FMA	71362
	Anatomical terminology [ edit on Wikidata]

Last updated February 12, 2024

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.

Thumb

Bones of a human wrist. In this photo both the free position and the saddle shape of the first CMC joint and the proximal transverse palmar arch are clearly visible. RightHumanAnteriorDistalRadiusUlnaCarpals.jpg — Bones of a human wrist. In this photo both the free position and the saddle shape of the first CMC joint and the proximal transverse palmar arch are clearly visible.

The carpometacarpal joint of the thumb (pollex), also known as the first carpometacarpal joint, or the trapeziometacarpal joint (TMC) because it connects the trapezium to the first metacarpal bone, plays an irreplaceable role in the normal functioning of the thumb. The most important joint connecting the wrist to the metacarpus, osteoarthritis of the TMC is a severely disabling condition; up to twenty times more common among elderly women than in average.^[1]

Pronation-supination of the first metacarpal is especially important for the action of opposition.^[1] The movements of the first CMC are limited by the shape of the joint, by the capsulo-ligamentous complex surrounding the joint, and by the balance among involved muscles. If the first metacarpal fails to sit well 'on the saddle', for example because of hypoplasia, the first CMC joint tends to be subluxated (i.e. slightly displaced) towards the radius.^[1]

The capsule is sufficiently slack to allow a wide range of movements and a distraction of roughly 3 mm, while reinforcing ligaments and tendons give stability to the joint. It is slightly thicker on its dorsal side than on the other.^[1]

The first carpometacarpal joint is a frequent site of osteoarthritis in postmenopausal women.^[2]

Ligaments

The description of the number and names of the ligaments of the first CMC varies considerably in anatomical literature. Imaeda et al. 1993 describe three intracapsular and two extracapsular ligaments to be most important in stabilizing the thumb:^[1]

Anterior oblique ligament (AOL): A strong, thick, and intracapsular ligament originating on the palmar tubercle of the trapezium to be inserted on the palmar tubercle of the first metacarpal. It is taut in abduction, extension, and pronation, and has been reported to have an important retaining function and to be elongated or absent in CMC joint arthritis.
Ulnar collateral ligament (UCL): An extracapsular ligament, the UCL is located ulnarly to the AOL. It has its origin on the flexor retinaculum and is inserted on the ulnopalmar tubercle of the first metacarpal. It is taut in abduction, extension, and pronation, and often found elongated in connection to CMC joint arthritis. The importance ascribed to the UCL varies considerably among researchers.
First intermetacarpal ligament (IML): Connecting the bases of the second and first metacarpals, this ligament inserts onto the ulnopalmar tubercle of the first metacarpal where its fibers intermingle with those of the UCL. It is taut in abduction, opposition, and supination. It has been reported to be the most important restraining structure of the first CMC joint by several researchers. Some consider it too weak to be able to stabilize the joint by itself, yet accept that together with the UCL it represents an important restraining structure.
Posterior oblique ligament (POL): An intracapsular ligament stretching from the dorsoulnar side of the trapezium to the ulno-palmar tubercle of the first metacarpal. Not considered an important ligament to the first CMC joint, it tightens during forced adduction and radial abduction.
Dorsoradial ligament (DRL): Like the previous ligament, the DRL is not considered important to the first CMC. It connects the dorsal sides of the trapezium and the first metacarpal.

Early, anatomically correct drawings of the ligaments of the first carpometacarpal joints were produced by Weitbrecht 1742.^[3]

Movements

In this articulation the movements permitted are flexion and extension in the plane of the palm of the hand, abduction and adduction in a plane at right angles to the palm, circumduction, and opposition.

It is by the movement of opposition that the tip of the thumb is brought into contact with the volar surfaces of the slightly flexed fingers. This movement is effected through the medium of a small sloping facet on the anterior lip of the saddle-shaped articular surface of the greater multangular (trapezium). The flexor muscles pull the corresponding part of the articular surface of the metacarpal bone on to this facet, and the movement of opposition is then carried out by the adductors.
Flexion of this joint is produced by the flexor pollicis longus and brevis, assisted by the opponens pollicis and the adductor pollicis.
Extension is effected mainly by the abductor pollicis longus, assisted by the extensores pollicis longus and brevis.
Adduction is carried out by the adductor; abduction mainly by the abductor pollicis longus and brevis, assisted by the extensors.

Range of motion for the first CMC is 53° of flexion/extension, 42° of abduction/adduction, and 17° of rotation.^[4]

Planes and axes of movements

The thumb's MP and CMC joints abduct and adduct in a plane perpendicular to the palm, a movement also referred to as "palmar abduction." The same joints flex and extend in a plane parallel to the palm, also referred to as "radial abduction," because the thumb moves toward the hand's radial side. Abduction and adduction occur around an antero-posterior axis, while flexion and extension occur around a lateral axis.^[5]

For ease of orientation, the thumbnail can be considered as resting in the thumb's frontal plane. Abduction and adduction of the first CMC (and MP) joint(s) occur in this plane; flexion and extension of the first CMC, MP, and IP joints occur in a plane that is perpendicular to the thumbnail. This remains true regardless of how the first metacarpal bone is being rotated during opposition and reposition.^[5]

Sexual dimorphism

Male and female thumb CMC joints are different in some aspects. In women, the trapezial articular surface is significantly smaller than the metacarpal surface, and its shape also differs from that of males. While most thumb CMC joints are more congruent in the radioulnar direction than the dorsovolar, female CMC joints are less globally congruent than male joints.^[6]

Evolution

A primitive autonomisation of the first ray took place in dinosaurs, while a real differentiation appeared in primitive primates approximately 70 million years ago. The shape of the human TMC joint dates back about 5 million years ago. As a result of evolution, the human thumb CMC joint has positioned itself at 80° of pronation, 40° of abduction, and 50° of flexion in relation to an axis passing through the stable second and third CMC joints.^[1]

Fingers

Section through the human wrist Gray336.png — Section through the human wrist

The second metacarpal articulates primarily with the trapezoid and secondarily with the trapezium and capitate.
The third metacarpal articulates primarily with the capitate,
The fourth metacarpal articulates with the capitate and hamate.
The fifth metacarpal articulates with the hamate.

^[7]

Among themselves, the four ulnar metacarpals also articulates with their neighbours at the intermetacarpal articulations.^[7]

Ligaments

These four CMC joints are supported by strong transverse and weaker longitudinal ligaments: the dorsal carpometacarpal ligaments and the volar or palmar carpometacarpal ligaments.^[7]

The interosseous ligaments consist of short, thick fibers, and are limited to one part of the carpometacarpal articulation; they connect the contiguous inferior angles of the capitate and hamate with the adjacent surfaces of the third and fourth metacarpal bones.

Movements

The carpometacarpal joints of second through fifth digits are arthrodial. The movements permitted in the second through fifth carpometacarpal joints most readily observable in the (distal) heads of the metacarpal bones. The range of motions in these joints decrease from the fifth to the second CMCs.^[8]

The second to fifth joints are synovial ellipsoidal joints with a nominal degree of freedom (flexion/extension). The second and third joints are however almost essentially immobile and can be considered to have zero degrees of freedom in practice, but capable of anteroposterior gliding (translation) movements.^[9]^[10]^[11] The second and third CMC however also capable of small degree of flexion-extension motion (11 degrees of flexion-extension motion for the second, while 7 degrees for the third).^[12] These two CMC provide the other three CMCs with a fixed and stable axis. While the mobility of the fourth CMC joint thus is perceptible, the first joint is a saddle joint with two degrees of freedom which except flexion/extension also enable abduction/adduction and a limited amount of opposition. Together the movements of the fourth and fifth CMCs facilitates for their fingers to oppose the thumb.^[8]

Function

The function of the finger carpometacarpal joints and their segments overall is to contribute to the palmar arch system together with the thumb. The proximal transverse arch of the palm is formed by the distal row of carpal bones. The concavity of this arch is augmented at the level of the metacarpal heads by the flexibility of the first, fourth, and fifth metacarpal heads around the fixed second and third metacarpal heads; a flexible structure called the distal transverse arch. For each finger there is also a longitudinal arch. Together, these arches allow the palm and the digits to conform optimally to objects as we grasp them (so-called palmar cupping). Furthermore, as the amount of surface contact is maximized, stability is enhanced and sensory feedback increases. The deep transverse metacarpal ligament stabilises the mobile parts of the palmar arch system.^[8]

As the fingers are being flexed, palmar cupping is contributed to by muscles crossing the carpometacarpal joints when they act on the mobile parts of the palmar arch system. The oblique opponens digiti minimi muscle acts on the fifth carpometacarpal joint and is the only muscle that act on the carpometacarpal joints alone. It is optimally positioned to flex and rotate the fifth metacarpal bone about its long axis. Palmar arching is further increased when [flexor carpi ulnaris] (which is attached to the pisiform) and intrinsic hand muscles attached to the transverse carpal ligament acts on the arch system. The fixed second and third carpometacarpal joints are crossed by the radial wrist muscles (flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis). The stability of these two carpometacarpal joints is a functional adaptation that enhances the efficiency of these muscles at the midcarpal and radiocarpal joints. ^[8]

Synovial membranes

The synovial membrane is a continuation of that of the intercarpal joints. Occasionally, the joint between the hamate and the fourth and fifth metacarpal bones has a separate synovial membrane.^{[ citation needed ]}

The synovial membranes of the wrist and carpus are thus seen to be five in number:^{[ citation needed ]}

The first passes from the lower end of the ulnar to the ulnar notch of the radius, and lines the upper surface of the articular disk.
The second passes from the articular disk and the lower end of the radius above, to the bones of the first row below.
The third, the most extensive, passes between the contiguous margins of the two rows of carpal bones, and sometimes, in the event of one of the interosseous ligaments being absent, between the bones of the second row to the carpal extremities of the second, third, fourth, and fifth metacarpal bones.
The fourth extends from the margin of the greater multangular to the metacarpal bone of the thumb.
The fifth runs between the adjacent margins of the triangular and pisiform bones.

Occasionally the fourth and fifth carpometacarpal joints have a separate synovial membrane.^{[ citation needed ]}

Clinical significance

Osteoarthritis of the carpometacarpal joints is a type of joint disease that results from breakdown of joint cartilage and underlying bone.^[13] When it affects the thumb it is termed trapeziometacarpal osteoarthritis.

Carpometacarpal bossing is the presence of a small immovable protuberance over the joint.^[14]

Notes

1 2 3 4 5 6 Brunelli 1999 , pp. 167–170
↑ Peter, J.; Marmor, L. (1968). "Osteoarthritis of the first carpometacarpal joint". California Medicine. 109 (2): 116–120. PMC 1503205 . PMID 5673986.
↑ Lewis 1977 , p. 160
↑ Austin 2005 , pp. 337–339
1 2 Thompson 2001
↑ Ateshian, Rosenwasser & Mow 1992
1 2 3 Austin 2005 , p. 319
1 2 3 4 Austin 2005 , p. 320
↑ Rad, Adrian. "Carpometacarpal (CMC) joints". kenhub.com. Retrieved September 26, 2022.
↑ Wise, Christopher H. "Orthopaedic Manual Physical Therapy: From Art to Evidence" F.A. Davis, 2015, p. 573.
↑ Neumann, Donald A. "Kinesiology of the Musculoskeletal System - E-Book: Foundations for Rehabilitation" Elsevier Health Sciences, 2013, p. 250.
↑ Skirven, Terri M., A. Lee Osterman, Jane Fedorcyzk, Peter C. Amadio "Rehabilitation of the Hand and Upper Extremity, 2-Volume Set E-Book: Expert Consult" Elsevier Health Sciences, 2011, p. 412.
↑ Atlas of Osteoarthritis. Springer. 2015. p. 21. ISBN 9781910315163.
↑ Conway, William F.; et al. (1984). "The Carpal Boss: An Overview of Radiographic Evaluation" (PDF). Radiology. 156 (1): 29–31. doi:10.1148/radiology.156.1.3923555. PMID 3923555.^{[ permanent dead link ]}

Related Research Articles

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">Thumb</span> First digit of the hand

The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position, the thumb is the outermost digit. The Medical Latin English noun for thumb is pollex, and the corresponding adjective for thumb is pollical.

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; (2) the wrist joint or radiocarpal joint, the joint between the 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. This region also includes the carpal tunnel, the anatomical snuff box, bracelet lines, the flexor retinaculum, and the extensor retinaculum.

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

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">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.

The flexor pollicis brevis is a muscle in the hand that flexes the thumb. It is one of three thenar muscles. It has both a superficial part and a deep part.

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.

In human anatomy, the palmar or volar interossei are four muscles, one on the thumb that is occasionally missing, and three small, unipennate, central muscles in the hand that lie between the metacarpal bones and are attached to the index, ring, and little fingers. They are smaller than the dorsal interossei of the hand.

The opponens digiti minimi is a muscle in the hand. It is of a triangular form, and placed immediately beneath the palmaris brevis, abductor digiti minimi and flexor digiti minimi brevis. It is one of the three hypothenar muscles that control the little finger.

The opponens pollicis is a small, triangular muscle in the hand, which functions to oppose the thumb. It is one of the three thenar muscles. It lies deep to the abductor pollicis brevis and lateral to the flexor pollicis brevis.

In human anatomy, the dorsal interossei (DI) are four muscles in the back of the hand that act to abduct (spread) the index, middle, and ring fingers away from hand's midline and assist in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints of the index, middle and ring fingers.

The first metacarpal bone or the metacarpal bone of the thumb is the first bone proximal to the thumb. It is connected to the trapezium of the carpus at the first carpometacarpal joint and to the proximal thumb phalanx at the first metacarpophalangeal joint.

<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.

$<span class="mw-page-title-main">Bennett's fracture</span> Medical condition$

Bennett fracture is a type of partial broken finger involving the base of the thumb, and extends into the carpometacarpal (CMC) joint.

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 are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.

<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">Trapeziometacarpal osteoarthritis</span> Medical condition

Trapeziometacarpal osteoarthritis (TMC OA) is, also known as osteoarthritis at the base of the thumb, thumb carpometacarpal osteoarthritis, basilar (or basal) joint arthritis, or as rhizarthrosis. This joint is formed by the trapezium bone of the wrist and the metacarpal bone of the thumb. This is one of the joints where most humans develop osteoarthritis with age. Osteoarthritis is age-related loss of the smooth surface of the bone where it moves against another bone (cartilage of the joint). In reaction to the loss of cartilage, the bones thicken at the joint surface, resulting in subchondral sclerosis. Also, bony outgrowths, called osteophytes (also known as “bone spurs”), are formed at the joint margins.

<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

This article incorporates text in the public domain from page 330 of the 20th edition of Gray's Anatomy (1918)

Ateshian, G A; Rosenwasser, M P; Mow, V C (June 1992). "Curvature characteristics and congruence of the thumb carpometacarpal joint: differences between female and male joints". J Biomech. 25 (6)): 591–607. doi: 10.1016/0021-9290(92)90102-7 . PMID 1517255. Archived from the original on 2010-08-28.
Austin, Noelle M. (2005). "Chapter 9: The Wrist and Hand Complex". In Levangie, Pamela K.; Norkin, Cynthia C. (eds.). Joint Structure and Function: A Comprehensive Analysis (4th ed.). Philadelphia: F. A. Davis Company. ISBN 978-0-8036-1191-7.
Brunelli, Giovanni R. (1999). "Stability of the first carpometacarpal joint". In Brüser, Peter; Gilbert, Alain (eds.). Finger bone and joint injuries. Taylor & Francis. pp. 167–170. ISBN 978-1-85317-690-6.
Imaeda, T; An, K N; Cooney, W P; Linscheid, R (1993). "Anatomy of trapeziometacarpal ligaments". The Journal of Hand Surgery. 18 (2): 226–31. doi:10.1016/0363-5023(93)90352-4. PMID 8463585.
Lewis, O J (February 1977). "Joint remodelling and the evolution of the human hand". J. Anat. 123 (Pt 1): 157–201. PMC 1234261 . PMID 402345.
Thompson, Dave (February 2001). "CMC Joint of the Thumb". University of Oklahoma Health Sciences Center. Archived from the original on 2009-11-18.
Weitbrecht, Josias (1742). "Syndesmologia sive, Historia ligamentorvm corporis hvmani qvam secvndvm observationes anatomicas concinnavit et figvris ad obiecta recentia advmbratis illvstravit Iosias Weitbrecht". University of Otago, NZ. Archived from the original on 2010-05-23.

External links

Hand kinesiology at the University of Kansas Medical Center - carpometacarpal joint
Hand kinesiology at the University of Kansas Medical Center - carpometacarpal ligaments
EatonHand joi-046

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[Brunelli-167-1] 1 2 3 4 5 6 Brunelli 1999 , pp. 167–170

[2] Peter, J.; Marmor, L. (1968). "Osteoarthritis of the first carpometacarpal joint". California Medicine. 109 (2): 116–120. PMC 1503205 . PMID 5673986.

[Lewis-1977-3] Lewis 1977 , p. 160

[Austin-337-4] Austin 2005 , pp. 337–339

[Thompson-5] 1 2 Thompson 2001

[6] Ateshian, Rosenwasser & Mow 1992

[Austin-319-7] 1 2 3 Austin 2005 , p. 319

[Austin-320-8] 1 2 3 4 Austin 2005 , p. 320

[9] Rad, Adrian. "Carpometacarpal (CMC) joints". kenhub.com. Retrieved September 26, 2022.

[Wise-10] Wise, Christopher H. "Orthopaedic Manual Physical Therapy: From Art to Evidence" F.A. Davis, 2015, p. 573.

[Neumann-11] Neumann, Donald A. "Kinesiology of the Musculoskeletal System - E-Book: Foundations for Rehabilitation" Elsevier Health Sciences, 2013, p. 250.

[Skirven-12] Skirven, Terri M., A. Lee Osterman, Jane Fedorcyzk, Peter C. Amadio "Rehabilitation of the Hand and Upper Extremity, 2-Volume Set E-Book: Expert Consult" Elsevier Health Sciences, 2011, p. 412.

[13] Atlas of Osteoarthritis. Springer. 2015. p. 21. ISBN 9781910315163.

[14] Conway, William F.; et al. (1984). "The Carpal Boss: An Overview of Radiographic Evaluation" (PDF). Radiology. 156 (1): 29–31. doi:10.1148/radiology.156.1.3923555. PMID 3923555.^{[ permanent dead link ]}

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Authority control databases
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Other	Terminologia Anatomica

Carpometacarpal joint

Contents

Thumb

Ligaments

Movements

Sexual dimorphism

Evolution

Fingers

Ligaments

Movements

Function

Synovial membranes

Clinical significance

Notes

Related Research Articles

References

External links