In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the
skeletal hand
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 "h ...
located between the
phalanges of the fingers and the
carpal bones of the
wrist
In human anatomy, the wrist is variously defined as (1) the Carpal bones, 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 ...
, which forms the connection to 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 metacarpal bones are analogous to the
metatarsal bones
The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...
in the foot.
Structure
![Metacarpus (left hand) dorsal view](https://upload.wikimedia.org/wikipedia/commons/8/8e/Metacarpus_%28left_hand%29_dorsal_view.png)
The metacarpals form a transverse arch to which the rigid row of distal carpal bones are fixed. The peripheral metacarpals (those of the thumb and little finger) form the sides of the cup of the palmar gutter and as they are brought together they deepen this concavity. The index metacarpal is the most firmly fixed, while the thumb metacarpal articulates with the trapezium and acts independently from the others. The middle metacarpals are tightly united to the carpus by intrinsic interlocking bone elements at their bases. The ring metacarpal is somewhat more mobile while the fifth metacarpal is semi-independent.
[Tubiana ''et al'' 1998, p 11]
Each metacarpal bone consists of a body or shaft, and two extremities: the ''head'' at the distal or digital end (near the fingers), and the ''base'' at the proximal or carpal end (close to the wrist).
Body
The ''body'' (''shaft'') is prismoid in form, and curved, so as to be convex in the longitudinal direction behind, concave in front. It presents three surfaces: medial, lateral, and dorsal.
* The ''medial'' and ''lateral surfaces'' are concave, for the attachment of the
interosseus muscles, and separated from one another by a prominent anterior ridge.
* The ''dorsal surface'' presents in its distal two-thirds a smooth, triangular, flattened area which is covered in by the tendons of the extensor muscles. This surface is bounded by two lines, which commence in small tubercles situated on either side of the digital extremity, and, passing upward, converge and meet some distance above the center of the bone and form a ridge which runs along the rest of the dorsal surface to the carpal extremity. This ridge separates two sloping surfaces for the attachment of the ''
interossei dorsales''.
* To the tubercles on the digital extremities are attached the collateral ligaments of the
metacarpophalangeal joints
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow ca ...
.
['' Gray's Anatomy''. (See infobox)]
Base
The ''base'' (''basis'') or ''carpal extremity'' is of a cuboidal form, and broader behind than in front: it articulates with the
carpal bones and with the adjoining metacarpal bones; its dorsal and volar surfaces are rough, for the attachment of
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 li ...
s.
Head
The ''head'' (''caput'') or ''digital extremity'' presents an oblong surface markedly convex from before backward, less so transversely, and flattened from side to side; it articulates with the
proximal phalanx
The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...
. It is broader, and extends farther upward, on the volar than on the dorsal aspect, and is longer in the antero-posterior than in the transverse diameter. On either side of the head is a tubercle for the attachment of the collateral ligament of the
metacarpophalangeal
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cav ...
joint.
The dorsal surface, broad and flat, supports the tendons of the
extensor muscles.
The volar surface is grooved in the middle line for the passage of the flexor tendons, and marked on either side by an articular eminence continuous with the terminal articular surface.
Neck
The neck, or ''subcapital'' segment, is the transition zone between the body and the head.
Articulations
Besides the
metacarpophalangeal joint
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cav ...
s, the metacarpal bones
articulate by
carpometacarpal joint
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.
The CMC joint of the thumb or the first CMC joint, also known as the trapeziometaca ...
s as follows:
# the
first
First or 1st is the ordinal form of the number one (#1).
First or 1st may also refer to:
*World record, specifically the first instance of a particular achievement
Arts and media Music
* 1$T, American rapper, singer-songwriter, DJ, and rec ...
with the
trapezium;
# the
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 ...
with the trapezium,
trapezoid
A quadrilateral with at least one pair of parallel sides is called a trapezoid () in American and Canadian English. In British and other forms of English, it is called a trapezium ().
A trapezoid is necessarily a Convex polygon, convex quadri ...
,
capitate
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 (the middle finger) and forms the third carpomet ...
and third metacarpal;
# the
third
Third or 3rd may refer to:
Numbers
* 3rd, the ordinal form of the cardinal number 3
* , a fraction of one third
* Second#Sexagesimal divisions of calendar time and day, 1⁄60 of a ''second'', or 1⁄3600 of a ''minute''
Places
* 3rd Street (d ...
with the capitate and second and fourth metacarpals;
# the
fourth with the capitate,
hamate
The hamate bone (from Latin hamatus, "hooked"), or unciform bone (from Latin ''uncus'', "hook"), Latin os hamatum and occasionally abbreviated as just hamatum, is a bone in the human wrist readily distinguishable by its wedge shape and a hook-l ...
, and third and fifth metacarpals;
# and the
fifth with the hamate and fourth metacarpal;
File:Carpus.jpg, Carpometacarpal joints
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.
The CMC joint of the thumb or the first CMC joint, also known as the trapeziometacar ...
of the left hand. Thumb on left.
File:Ospoignet.gif, Carpometacarpal joints of the left hand. Thumb on left.
File:814 Radiograph of Hand.jpg, X-ray
Insertions
''
Extensor Carpi Radialis Longus/
Brevis'': Both insert on the base of metacarpal II; Assist with wrist extension and radial flexion of the wrist
''
Extensor Carpi Ulnaris
In human anatomy, the extensor carpi ulnaris is a skeletal muscle located on the ulnar side of the forearm. The extensor carpi ulnaris acts to extend and adduct at the carpus/wrist from anatomical position.
Being an extensor muscle, extensor carp ...
'': Inserts on the base of metacarpal V; Extends and fixes wrist when digits are being flexed; assists with ulnar flexion of wrist
''
Abductor Pollicis Longus
In human anatomy, the abductor pollicis longus (APL) is one of the extrinsic muscles of the hand. Its major function is to abduct the thumb at the wrist. Its tendon forms the anterior border of the anatomical snuffbox.
Structure
The abductor ...
'': Inserts on the trapezium and base of metacarpal I; Abducts thumb in frontal plane; extends thumb at carpometacarpal joint
''
Opponens Pollicis
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.
Structure
The op ...
'': Inserts on metacarpal I; flexes metacarpal I to oppose the thumb to the fingertips
''
Opponens digiti minimi
The opponens digiti minimi (opponens digiti quinti in older texts) 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 t ...
'': Inserts on the medial surface of metacarpal V; Flexes metacarpal V at carpometacarpal joint when little finger is moved into opposition with tip of thumb; deepens palm of hand.
[Saladin, Kenneth S. "Capt. 10." Anatomy & Physiology: the Unity of Form and Function. Dubuque: McGraw-Hill, 2010. 361-64. Print.]
File:Gray219 - Metacarpus.png, Metacarpus (yellow). Insertions are shown in red. Left hand, anterior (palmar) view.
File:Gray220 - Metacarpus.png, Metacarpus (yellow). Insertions are shown in red. Left hand, posterior (dorsal) view.
Clinical significance
Congenital disorders
The fourth and fifth metacarpal bones are commonly "blunted" or shortened, in
pseudohypoparathyroidism
Pseudohypoparathyroidism is a condition associated primarily with resistance to the parathyroid hormone. Those with the condition have a low serum calcium and high phosphate, but the parathyroid hormone level (PTH) is appropriately high (due to th ...
and
pseudopseudohypoparathyroidism
Pseudopseudohypoparathyroidism (PPHP) is an inherited disorder, named for its similarity to pseudohypoparathyroidism in presentation. It is more properly Albright hereditary osteodystrophy although without resistance of parathyroid hormone as fr ...
.
A blunted fourth metacarpal, with normal fifth metacarpal, can signify
Turner syndrome
Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic condition in which a female is partially or completely missing an X chromosome. Signs and symptoms vary among those affected. Often, a short and webbed neck, low-set ears, low hair ...
.
Blunted metacarpals (particularly the fourth metacarpal) are a symptom of
nevoid basal-cell carcinoma syndrome
Nevoid basal-cell carcinoma syndrome (NBCCS) is an inherited medical condition involving defects within multiple body systems such as the skin, nervous system, eyes, endocrine system, and bones. People with this syndrome are particularly prone to ...
.
Fracture
The neck of a metacarpal is a common location for a
boxer's fracture, but all parts of the metacarpal bone (including head, body and base) are susceptible to fracture. Several types of treatment exist ranging from non-operative techniques, with or without immobilization, to operative techniques using closed or
open reduction and internal fixation (ORIF). Generally, most fractures showing little or no displacement can be treated successfully without surgery.
Intraarticular fracture-dislocations of the metacarpal head or base may require surgical fixation, as fragment displacement affecting the joint surface is rarely tolerated well.
Other animals
![Evolution pl](https://upload.wikimedia.org/wikipedia/commons/5/5b/Evolution_pl.png)
In four-legged animals, the metacarpals form part of the forefeet, and are frequently reduced in number, appropriate to the number of toes. In
digitigrade and
unguligrade
Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ca ...
animals, the metacarpals are greatly extended and strengthened, forming an additional segment to the limb, a feature that typically enhances the animal's speed. In both
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
s and
bat
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...
s, the metacarpals form part of the wing.
History
Etymology
The Greek
physician
A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
Galen
Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one of ...
used to refer to the as μετακάρπιον.
[Hyrtl, J. (1880). ''Onomatologia Anatomica. Geschichte und Kritik der anatomischen Sprache der Gegenwart.'' Wien: Wilhelm Braumüller. K.K. Hof- und Universitätsbuchhändler.][Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie.'' Oxford: Clarendon Press.] The Latin form
[Schreger, C.H.Th.(1805). ''Synonymia anatomica. Synonymik der anatomischen Nomenclatur.'' Fürth: im Bureau für Literatur.][Triepel, H. (1908). Memorial on the anatomical nomenclature of the anatomical society. In A. Rose (Ed.), ''Medical Greek. Collection of papers on medical onomatology and a grammatical guide to learn modern Greek'' (pp. 176-193). New York: Peri Hellados publication office.][Triepel, H. (1910). ''Nomina Anatomica. Mit Unterstützung von Fachphilologen.'' Wiesbaden: Verlag J.F. Bergmann.] more truly resembles
its Ancient Greek predecessor μετακάρπιον than metacarpus.
[His, W. (1895). ''Die anatomische Nomenclatur. Nomina Anatomica. Der von der Anatomischen Gesellschaft auf ihrer IX. Versammlung in Basel angenommenen Namen''. Leipzig: Verlag Veit & Comp.][Federative Committee on Anatomical Terminology (FCAT) (1998). ''Terminologia Anatomica''. Stuttgart: Thieme] Meta– is Greek for beyond and carpal from Ancient Greek ''καρπός'' (, “wrist”).
In anatomic Latin, adjectives like ,
[Triepel, H. (1910). ''Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit einem Anhang: Biographische Notizen.''(Dritte Auflage). Wiesbaden: Verlag J.F. Bergmann.] ,
[Triepel, H. & Stieve, H. (1936). ''Die anatomischen Namen. Ihre Ableitung und Aussprache. Anhang: Eigennamen, die früher in der Anatomie verwendet wurden.''(Achtzehnte Auflage). Berlin/Heidelberg:Springer-Verlag.] ,
[Siebenhaar, F.J. (1850). ''Terminologisches Wörterbuch der medicinischen Wissenschaften.'' (Zweite Auflage). Leipzig: Arnoldische Buchhandlung.] ,
[International Anatomical Nomenclature Committee (1966). ''Nomina Anatomica'' . Amsterdam: Excerpta Medica Foundation.] [Foster, F.D. (1891-1893). ''An illustrated medical dictionary. Being a dictionary of the technical terms used by writers on medicine and the collateral sciences, in the Latin, English, French, and German languages.'' New York: D. Appleton and Company.] and
can be found. The form is more true
to the later Greek form μετακάρπιος.
, as in in the current official Latin nomenclature, ''
Terminologia Anatomica
''Terminologia Anatomica'' is the international standard for human anatomical terminology. It is developed by the Federative International Programme on Anatomical Terminology, a program of the International Federation of Associations of Anatomis ...
''
is a compound consisting of Latin and Greek parts.
The usage of such hybrids in anatomic Latin is disapproved by some.
Additional images
File:Metacarpal bones (left hand) - animation01.gif, Metacarpus of the left hand (shown in red). Animation.
File:Medical X-Ray imaging VNH07 nevit.jpg, X-ray image of right hand with thumb on left.
File:Metacarpal fractures.jpg, Multiple fractures of the metacarpals (aka broken hand). (Right hand shown with thumb on left.)
File:Medical X-Ray imaging OCU06 nevit.jpg, X-ray image of human infant left hand.
File:Hand of embryo.jpg, Micro-radiography of 8 weeks human embryo hand
File:Slide1dsds.JPG, Right hand. Deep dissection. Anterior (palmar) view.
File:Slide1tyty.JPG, Right hand. Deep dissection. Posterior (dorsal) view.
See also
*
Carpometacarpal bossing
References
Further reading
*
{{Authority control
Skeletal system
Hand
Bones of the hand
Long bones