METACARPAL BONES:
• 5 miniature long bones 🦴.
• Numbered from lateral to the medial side.
• Each bone has a distal head, a shaft, and a proximal base.
• Head is round and forms the knuckles 👊.
• Shaft is concave on the palmar surface 🤲.
• Base is irregularly expanded.
🔳1ST MC BONE:
• Shortest and stoutest.
• Base is occupied by a convexo-concave articular surface for trapezium.
• Ulnar & radial corners of the palmar surface have impressions for sesamoid bones.
• Anterolateral surface is larger than the anteromedial.
🔳2ND MC BONE:
• Base is grooved from before backwards.
• Medial edge of the groove on the base is deeper than the lateral edge.
🔳3RD MC BONE:
• Base has a styloid process projecting up from the dorsolateral corner.
• Styloid process is dorsolateral.
• Medial side of the base has 2 small oval facets for the 4th metacarpal.
🔳4TH MC BONE:
• Base has two small oval facets on its lateral side for the third metacarpal.
• Medial side has a single elongated facet for the 5th metacarpal.
• Lateral side of the base has 2 small oval facets for the 3rd metacarpal.
• Medial side of the base has an elongated articular strip for the 5th metacarpal.
🔳5TH MC BONE:
• Base has an elongated articular strip on its lateral side for the 4th metacarpal.
• Medial side of the base is non-articular and bears a tubercle.
• Lateral side of the base has an elongated articular strip for the 4th metacarpal.
