Ans. (c) Middle FingerRef: Grays Anatomy 41st Ed; Page No- 884* The four dorsal interossei muscles are bipennate in nature.* They are larger in size compare to palmar interossei.* They are arising from the adjacent sides of two metacarpal bones.* First two attach to radial side of proximal phalanx of index and middle finger and blend with dorsal digital expansion.* The third and fourth to ulnar side of proximal phalanx of middle and ring finger and blend with dorsal digital expansion.* The second and third are attached to the radial and ulnar sides of the middle finger, respectively.Action of the interossei musclesPalmar Interossei* It unipennate in natures.* Location: On the palmar surface between the metacarpals.* All fingers have palmar interossei; except;- Mid die finger.* They are arising from palmar aspects of the metacarpals.* It adduct the fingers towards the longitudinal axis of the middle fingerDorsal Interossei* It abducts the fingers away from the longitudinal axis of the middle finger.* Note: Fifth finger is not abducted by dorsal interossei.Extra MileInterosseiMuscleOriginInsertionNerve supplyNerve rootActionDorsal interossei (4) (bipennate)Adjacent sides of metacarpal bonesLateral sides of bases of proximal phalanges; extensor expansionUlnarC8;Abduct fingers; flex metacarpo- phalangeal joints; extend inter- phalangeal jointsT1Palmar interossei (3) (unipennate) Medial side of second metacarpal; lateral sides of fourth and fifth metacarpalsBases of proximal phalanges in same sides as their origins; extensor expansionUlnarC8;Adduct fingers; flex metacarpo- phalangeal joints; extend inter- phalangeal jointsT1 Movement at the Metacarpophalangeal JointDorsal interosseiAbductionPalmar interosseiAdductionExtensor digitorumExtensionLumbricals and interosseiFlexion