In relation to other metacarpals, the first metacarpal is
The 1st metacarpal bone (lying on a more anterior plane ) is rotated medially through 90deg relative to other metacarpals. As a result of this rotation , the movements of the thumb take place at right angles to those of other digits. B D Chaurasia 7th edition Page no : 29
Posterior
Anterior
Laterally rotated
Dorsally rotated
Upper limb