Metacarpals

METACARPAL BONES
Ox, Sheep and Goat, Horse, Pig, Dog, Rabbit, Fowl)

Ox

The metacarpus consists of a large metacarpal(fifth ). (fused third and fourth) , which carries the digit and a lateral small metacarpal

LARGE METACARPAL

It is a bone placed vertically between the carpus above and fetlock below. It results from the fusion of third and fourth metacarpals.It consists of a shaft and two extremities. 

  • Shaft
    • It is  semi-cylindrical and as two surfaces and two borders .
    •  The dorsal surface is convex transversely and is marked by a vertical vascular groove at either end (usually at the distal end) of which is a foramen, which traverses the thickness of the shaft.
    • The volar surface is flat from side to side and presents a shallow vertical groove, which communicates with the anterior groove through the foramina described above. This surface is in contact with the superior sesamoidean ligament.
    • The borders are medial and lateral and rounded. The latter, at its upper part has the lateral small metacarpal attached to it posteriorly.
  • Proximal extremity
    • It has two facets separated by a ridge in front and a notch behind.
    • The medial facet is larger and corresponds to the second and third carpal and lateral to the fourth carpal. At the dorsal aspect of this extremity is the metacarpal tuberosity for the extensor carpi radialis. At the postero-medial aspect is a tubercle for the attachment of extensor carpi obliquus. The lateral aspect of the volar face bears a small facet for the lateral small metacarpal.
  • Distal extremity
    • It is divided into two parts by a sagittal cleft.
    • Each part is made of two condyles separated by a sagittal ridge for articulation with the first phalanx below and two sesamoids behind.
    • The medial condyle is slightly larger than the lateral.
    • The abaxial aspects of each division are depressed for ligamentous attachment.

LATERAL SMALL METACARPAL (fifth metacarpal)

  • It is an aborted long bone and is an inch and a half long.
  • The bone is attached to the postero-lateral aspect of the proximal extremity of the large metacarpal.
  • The proximal extremity is rounded and bears a small facet on the anterior face for the large metacarpal.
  • The distal extremity is pointed.

metacarpls

TOP

Sheep and Goat

  •  Large metacarpal resembles that of an ox.
  • The small metacarpal is usually absent.If present, it is in the form of a ridge on the large metacarpal bone.

TOP

Horse

The metacarpus consists of one large metacarpal (third) two small metacarpals or splints (second and fourth).

  • Large metacarapal
    • The vascular grooves on the dorsal and volar faces are absent.
    • The volar face is roughened on either side in its proximal two thirds for attachment of the splints with which it forms a wide groove for the lodgment of suspensory ligament.
    • It articulates with the second, third and fourth carpals above and by means of small facets on either side, with the proximal extremities of the splints.
    • The distal extremity of the large metacarpal resembles one of the parts of the distal extremity of large metacarpal of the ox.
    • The medial condyle of the articular area for the first phalanx is slightly larger than that of the lateral.
  • Small metacarpals 
    • The shaft of each is three sided.
    • The dorsal face is rough for attachment to the large metacarpal.
    • The proximal extremity is relatively massive and has one or two facets dorso-laterally for the large metacarpal.
    • The medial bone bears two facets above for the second and the third carpals while the lateral presents one facet for the fourth.
    • The distal extremity is in the form of a small nodule and usually forms the ‘button’ of the splint.

TOP

Pig

  • Has four bones.
  • The first is absent.
  • Third and fourth metacarpals are large and carry the chief digits.
  • The second and fifth are much smaller and bear the accessory digits.

TOP

Dog

  •  Has five bones.
  • The first is the shortest.
  • The third and the fourth are longest.
  • The second is longer than the fifth.
  • The lie close together above but diverges distally.
  • The proximal ends articulate with each other and the first four with the corresponding carpals.
  • The fifth also articulates with the fourth carpal.

TOP

Rabbit

  •  Has five bones in each.
  • They are all cylindrical shape.
  • First one is smallest and the third and fourth is longest.

TOP

Fowl

  • The metacarpus includes three bony elements, which fuse together with the lower row of carpal bones to form a single bone, carpo-metacarpus.
  • The first i.e. most medial is in the form of a nodule projecting from the upper extremity of the second bone to which it is united.
  • The second and third bones are united at their extremities; narrow interval separates their shafts.

TOP
Last modified: Friday, 13 April 2012, 6:46 AM