A patient comes in complaining that she cannot flex her hand at the joint marked by a black arrow in the diagram. Which of the following muscles appear(s) to be paralyzed on fuher examination of her finger?: (A) Palmar interossei, (B) Dorsal interossei, (C) Flexor digitorum profundus, (D) Flexor digitorum superficialis
Answer is D. The flexor digitorum superficialis muscle flexes the proximal interphalangeal joints. The flexor digitorum profundus muscle flexes the Distal interphalangeal joints (DIP joints) The palmar and dorsal interossei and lumbricals can flex metacarpophalangeal joints and extend the interphalangeal joints. The palmar interossei adduct the fingers(PAD) The dorsal interossei abduct the fingers.(DAB)