Metacarpal bones

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Metacarpal bones
Metacarpal bones (left hand) 01 palmar view with label.png
Metacarpals shown in red. Left hand, anterior (palmar) view.
Metacarpus ant with label.png
The five metacarpal bones, numbered. Left hand, anterior (palmar) view.

os primum metacarpale / os metacarpale I

os secundum metacarpale / os metacarpale II

os tertium metacarpale / os metacarpale III

os quartum metacarpale / os metacarpale IV

os quintum metacarpale / os metacarpale V
Details
Origins Carpal bones of wrist
InsertionsProximal phalanges
Articulations Carpometacarpal, intermetacarpal, metacarpophalangeal
Identifiers
Latin os metacarpale
pl. ossa metacarpalia
MeSH D050279
TA98 A02.4.09.001
TA2 1264
FMA 9612
Anatomical terms of bone

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 (wrist bones), which articulate with the forearm. The metacarpal bones are homologous to the metatarsal bones in the foot.

Contents

Structure

Left hand shown with thumb on left. Metacarpus (left hand) dorsal view.png
Left hand shown with thumb on left.

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. [1]

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.

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 ligaments. [2]

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. 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 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. [2]

Neck

The neck, or subcapital segment, is the transition zone between the body and the head.

Articulations

Besides the metacarpophalangeal joints, the metacarpal bones articulate by carpometacarpal joints as follows:

  1. the first with the trapezium;
  2. the second with the trapezium, trapezoid, capitate and third metacarpal;
  3. the third with the capitate and second and fourth metacarpals;
  4. the fourth with the capitate, hamate, and third and fifth metacarpals;
  5. and the fifth with the hamate and fourth metacarpal;

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 : 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 : Inserts on the trapezium and base of metacarpal I; Abducts thumb in frontal plane; extends thumb at carpometacarpal joint

Opponens Pollicis : Inserts on metacarpal I; flexes metacarpal I to oppose the thumb to the fingertips

Opponens digiti minimi : 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. [3]

Clinical significance

Congenital disorders

The fourth and fifth metacarpal bones are commonly "blunted" or shortened, in pseudohypoparathyroidism and pseudopseudohypoparathyroidism.

A blunted fourth metacarpal, with normal fifth metacarpal, can signify Turner syndrome.

Blunted metacarpals (particularly the fourth metacarpal) are a symptom of nevoid basal-cell carcinoma syndrome.

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. During their lifetime, 2.5% of individuals will experience at least one metacarpal fracture. Bennett's fracture (base of the thumb) is the most common. [4] 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. [5] Intraarticular fracture-dislocations of the metacarpal head or base may require surgical fixation, as fragment displacement affecting the joint surface is rarely tolerated well. [5]

Other animals

The principle of homology illustrated by the adaptive radiation of the metacarpal bones of mammals. All conform to the basic pentadactyl pattern but are modified for different usages. The third metacarpal is shaded throughout; the shoulder is crossed-hatched. Evolution pl.png
The principle of homology illustrated by the adaptive radiation of the metacarpal bones of mammals. All conform to the basic pentadactyl pattern but are modified for different usages. The third metacarpal is shaded throughout; the shoulder is crossed-hatched.

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 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 birds and bats, the metacarpals form part of the wing.

History

Etymology

The Greek physician Galen used to refer to the metacarpus as μετακάρπιον. [6] [7] The Latin form metacarpium [6] [8] [9] [10] more truly resembles [6] its Ancient Greek predecessor μετακάρπιον than metacarpus. [11] [12] Meta– is Greek for beyond and carpal from Ancient Greek καρπός (karpós, “wrist”). In anatomic Latin, adjectives like metacarpius, [13] metacarpicus, [14] metacarpiaeus, [15] metacarpeus, [16] metacarpianus [17] and metacarpalis [12] can be found. The form metacarpius is more true [9] [13] to the later Greek form μετακάρπιος. [13] Metacarpalis, as in ossa metacarpalia in the current official Latin nomenclature, Terminologia Anatomica [12] is a compound consisting of Latin and Greek parts. [14] The usage of such hybrids in anatomic Latin is disapproved by some. [9] [14]

Additional images

See also

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">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.

<span class="mw-page-title-main">Wrist</span> Part of the arm between the lower arm and the hand

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.

<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">Trapezoid bone</span> Carpal (wrist) bone

The trapezoid bone is a carpal bone in tetrapods, including humans. It is the smallest bone in the distal row of carpal bones that give structure to the palm of the hand. It may be known by its wedge-shaped form, the broad end of the wedge constituting the dorsal, the narrow end the palmar surface; and by its having four articular facets touching each other, and separated by sharp edges. It is homologous with the "second distal carpal" of reptiles and amphibians.

<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">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">Hamate bone</span> Carpal bone in the wrist

The hamate bone, or unciform bone, 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-like process ("hamulus") projecting from its palmar surface.

<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">Flexor pollicis brevis muscle</span> Muscle in the thenar compartment

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.

<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">First metacarpal bone</span>

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">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">Palmar plate</span>

In the human hand, palmar or volar plates are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints, where they reinforce the joint capsules, enhance joint stability, and limit hyperextension. The plates of the MCP and IP joints are structurally and functionally similar, except that in the MCP joints they are interconnected by a deep transverse ligament. In the MCP joints, they also indirectly provide stability to the longitudinal palmar arches of the hand. The volar plate of the thumb MCP joint has a transverse longitudinal rectangular shape, shorter than those in the fingers.

<span class="mw-page-title-main">Hand</span> Extremity at the end of an arm or forelimb

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">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

PD-icon.svgThis article incorporates text in the public domain from page 227 of the 20th edition of Gray's Anatomy (1918)

  1. Tubiana et al 1998, p 11
  2. 1 2 3 Gray's Anatomy . (See infobox)
  3. Saladin, Kenneth S. "Capt. 10." Anatomy & Physiology: the Unity of Form and Function. Dubuque: McGraw-Hill, 2010. 361-64. Print.
  4. Goru, Poornanand; Haque, Syed; Verma, Gopalkrishna G.; Mustafa, Abubakar; Ebinesan, Ananthan (2022). "Bennett's Fracture Management: A Systematic Review of Literature". Cureus. 14 (11): e31340. doi: 10.7759/cureus.31340 . ISSN   2168-8184. PMC   9733783 . PMID   36514567.
  5. 1 2 GREEN'S OPERATIVE HAND SURGERY : 2-volume set. [S.l.]: ELSEVIER - HEALTH SCIENCE. 2022. ISBN   978-0-323-69793-4. OCLC   1255690810.
  6. 1 2 3 Hyrtl, J. (1880). Onomatologia Anatomica. Geschichte und Kritik der anatomischen Sprache der Gegenwart. Wien: Wilhelm Braumüller. K.K. Hof- und Universitätsbuchhändler.
  7. 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.
  8. Schreger, C.H.Th.(1805). Synonymia anatomica. Synonymik der anatomischen Nomenclatur. Fürth: im Bureau für Literatur.
  9. 1 2 3 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.
  10. Triepel, H. (1910). Nomina Anatomica. Mit Unterstützung von Fachphilologen. Wiesbaden: Verlag J.F. Bergmann.
  11. 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.
  12. 1 2 3 Federative Committee on Anatomical Terminology (FCAT) (1998). Terminologia Anatomica. Stuttgart: Thieme
  13. 1 2 3 Triepel, H. (1910). Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit einem Anhang: Biographische Notizen.(Dritte Auflage). Wiesbaden: Verlag J.F. Bergmann.
  14. 1 2 3 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.
  15. Siebenhaar, F.J. (1850). Terminologisches Wörterbuch der medicinischen Wissenschaften. (Zweite Auflage). Leipzig: Arnoldische Buchhandlung.
  16. International Anatomical Nomenclature Committee (1966). Nomina Anatomica . Amsterdam: Excerpta Medica Foundation.
  17. 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.

Further reading