The metacarpus is part of the skeleton of the palmar region and is made up of five elongated bones, called the metacarpals . Between them the interosseous spaces are limited.


What is the metacarpus?

The metacarpus is the skeleton of the palmar region that joins the carpus with the phalanges and consists of five metacarpal bones . In some literatures they are listed from one to five, starting with the thumb .

  • Definition
  • Metacarpal characteristics
  • What is it for
  • Parties
  • Location
  • Metacarpal bones
  • Function
  • Metacarpal injuries
  • Care
  • Importance


It is the skeleton of the hand that joins the carpus with the phalanges and consists of five metacarpal bones . The distal extremities articulate with the proximal phalanx and form the knuckles, and the proximal extremities articulate with the carpal bones.


Metacarpal characteristics

The main characteristics of the metacarpus are:

  • Joins the carpus and phalanges.
  • Each metacarpus has a body, neck, and two limbs or heads .
  • They occupy the entire palm of the hand.
  • The I metacarpal is related to the thumb.
  • The II to V metacarpal are related to the index to the little finger respectively.
  • The base of the metacarpals articulate with the carpal bones and in turn the metacarpal bases articulate with each other, with the exception of the 1st metacarpal.
  • They have a thick peripheral coat, spongy tissue on their extremities.
  • Its medullary cavity is reduced.

What is it for

The metacarpal bones support the palm of the hand and allow the insertion of muscles to perform movements such as bringing the thumb to the center of the palm or flexing the metacarpal joints.


In the metacarpals we will describe a body or diaphysis , neck or metaphysis and two epiphyses or heads.

  • The diaphysis has an anterior concavity (palmar) and a triangular prismatic shape, it has a slightly convex posterior face and two faces, lateral and medial, in relation to the interosseous muscles.
  • Its metaphysis is a narrow part that joins the diaphysis with the epiphysis.
  • The proximal epiphysis, or base of the metacarpal, presents articular faces for the bones of the inferior carpal row and the other neighboring metacarpals.
  • The distal epiphysis , the head of the metacarpal, articulates with the base of the corresponding proximal phalanges.


The metacarpal bones are located vertically in the palmar region.

Metacarpal bones

  • I metacarpal: corresponds to the thumb . This pastern is the thickest and the shortest. It does not articulate with the other metacarpals and does not have lateral articular facets. It articulates with the trapezius bone.
  • II metacarpal: also called the index finger . It is the longest metacarpal. It has a medial articular facet for the III metacarpal. It articulates with the trapezoid and trapezoid.
  • III metacarpal: or middle finger , it has two articular facets at its base and the styloid process stands out on its dorsal side for the insertion of the extensor carpi radialis brevis muscle. It articulates with the large carpal bone.
  • IV metacarpal: or ring finger , it has two articular facets but does not have a styloid process. It articulates with the large and hamate bones.
  • V metacarpal: or little finger , it only has an articular facet on the lateral side. It articulates with the hamate bone.


The metacarpals serve as support for the palmar region, they provide its structure for the insertion of muscles that facilitate certain movements of the wrist and fingers of the hand.

Metacarpal injuries

  • Sprain of the metacarpophalangeal or metacarpocarpal joint : A violent strain of a joint occurs and this can cause the rupture of muscle fibers or ligaments.
  • Dislocations: which consists of the complete dislocation of any metacarpal bone, that is, when a bone comes out of its joint.
  • Rolando’s fracture: it is an intra-articular and commutation fracture, in the shape of a V. It occurs at the base of the 1st metacarpal. It is difficult to reconstruct surgically and they usually recover with orthopedic treatment.
  • Bennett’s fracture: it is an unstable intra-articular oblique fracture. There is proximal displacement of the shaft by action of the adductor pollicis longus muscle.
  • Diaphyseal bills: they are angled or rotated fractures, quite unstable that require surgical intervention. Sometimes it is necessary to rebuild other structures such as tendons, vessels and nerves.
  • Boxer’s fracture: it is a fracture of the distal epiphysis of the neck of the V metacarpal, usually caused by punching.
  • Base fractures or Bora: it is an intra-articular fracture of the base of the V metacarpal with medial displacement of the diaphysis. Treatment consists of immobilization with a Boehler splint and if the displacement is significant it will require a surgical intervention.


To take care of the metacarpal bones from injuries, it is essential to carry out the movements in an ergonomic way , at home, at work or when doing any physical activity .


The metacarpal bones are of great importance for the support of the palm of the hand and allow us not only to perform movements but also to hold objects with our hands; this facilitates our day to day .

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