VIRTUAL 3D ANATOMICAL MODEL LEFT METACARPAL OF OX

In the ox, the metacarpal bones are vital for supporting the body’s weight and enabling movement. There are two metacarpal bones:

• The large metacarpal bone (canon bone).
• The small metacarpal bone.

Large Metacarpal Bone

The large metacarpal bone is a fusion of the third and fourth metacarpal bones, forming a single strong structure known as the canon bone.

Key Features:

• External Grooves: Visible along the surface, marking the fusion of the two bones.
• Internal Structure: Contains two medullary cavities (hollow spaces for marrow).
• Shape: Cylindrical, with two main surfaces:

1. Anterior Surface (Front Surface)

• Convex and smooth, curving from side to side.
• Blends into the lateral (outer) and medial (inner) sides of the bone.
• A vertical groove runs down the center, starting at the top (proximal) and ending at the bottom (distal).
• The groove connects to a foramen (hole) on the posterior surface.

2. Posterior Surface (Back Surface)

• Flat and wide, especially at both ends.
• Features a vertical groove for attaching the superior ligament.

Ends of the Large Metacarpal Bone

Proximal End (Top End):

• Two articular facets (smooth surfaces for joint connection):
  1. A large facet articulates with the second and third carpal bones.
  2. A smaller facet on the side articulates with the fourth carpal bone.
• Below the smaller facet is a small joint area for the small metacarpal bone.

Distal End (Bottom End):

• Divided by a ridge into two parts, each articulating with the first phalanx (toe bone).
• Above the condyles (rounded parts), there are four depressions, which fit the proximal sesamoid bones (small bones in the joint).

Small Metacarpal Bone

The small metacarpal bone is a narrow, rod-like bone located behind and to the side (posterolateral) of the large metacarpal bone.

Key Features:

• Proximal End: Broad and connects to the large metacarpal bone.
• Distal End: Narrower and often fused with the large metacarpal bone.
• This bone helps stabilize the limb.

Summary Points for Students

1. The large metacarpal bone (canon bone) is made from the fusion of the third and fourth metacarpals.
2. Grooves and foramina on the bone allow the passage of nerves, blood vessels, and attachment of ligaments.
3. The small metacarpal bone is slender and supports the large metacarpal bone.
4. Proximal and distal ends have specialized surfaces for articulation with other bones (carpal bones proximally and the first phalanx distally).