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The first metacarpal bone is short and thick with a shaft thicker and broader than those of the other metacarpal bones. Its narrow shaft connects its widened base and rounded head; the former consisting of a thick [[cortical bone]] surrounding the open [[medullary canal]]; the latter two consisting of [[cancellous bone]] surrounded by a thin cortical shell.
<ref name="Doyle-Osteology">{{harvnb|Doyle|Botte|2003| loc=Osteology of the Thumb Metacarpal}}</ref><!-- ref for para -->
=== Head ===▼
The head is less rounded and less spherical than those of the other metacarpals, making it better suited for a hinge-like articulation.▼
The distal articular surface is quadrilateral, wide, and flat; thicker and broader transversely and extends much further palmarly than dorsally. On the palmar aspect of the articular surface there is a pair of eminences or tubercles which articulate with the radial and ulnar [[sesamoid bone]]s of the thumb metacarpophalangeal joint; the lateral eminence is larger than the medial.▼
<ref name="Doyle-Head">{{harvnb|Doyle|Botte|2003| loc=Head of the Thumb Metacarpal}}</ref><!-- ref for subsection -->▼
=== Body/Shaft ===
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<ref name="Doyle-Base">{{harvnb|Doyle|Botte|2003| loc=Base of the Thumb Metacarpal}}</ref><!-- ref for subsection -->
▲=== Head ===
▲The head is less rounded and less spherical than those of the other metacarpals, making it better suited for a hinge-like articulation.
▲The distal articular surface is quadrilateral, wide, and flat; thicker and broader transversely and extends much further palmarly than dorsally. On the palmar aspect of the articular surface there is a pair of eminences or tubercles which articulate with the radial and ulnar [[sesamoid bone]]s of the thumb metacarpophalangeal joint; the lateral eminence is larger than the medial.
▲<ref name="Doyle-Head">{{harvnb|Doyle|Botte|2003| loc=Head of the Thumb Metacarpal}}</ref><!-- ref for subsection -->
== Ossification ==
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File:First metacarpal bone (left hand) - animation01.gif|First metacarpal bone of the left hand (shown in red). Animation.
File:First metacarpal bone (left hand) - animation02.gif|First metacarpal bone of the left hand. Close up.
File:Gray219 - First metacarpal bone.png|Palmer view of the left hand (
File:Gray220 - First metacarpal bone.png|Dorsal view of the left hand (
File:Rolando fracture.jpg|Fracture of the first metacarpal ([[Rolando's fracture]]).
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