The 4 dorsal interossei are located in which layer?

The 4 dorsal interossei are located in which layer?

• A. 1st layer
• B. 2nd layer
• C. 3rd layer
• D. 4th layer

Answer: (D)

This question tests how the hand’s intrinsic muscles are organized into layers and where the dorsal interossei sit. The four dorsal interossei are positioned deepest among the intrinsic palm muscles, lying between adjacent metacarpals. Their placement between the metacarpals places them in the fourth, or deepest, layer of the palm’s muscular plan. Because of this, they occupy the fourth layer rather than the more superficial layers. These muscles act to abduct the fingers away from the middle finger and are innervated by the deep branch of the ulnar nerve.

This question tests how the hand’s intrinsic muscles are organized into layers and where the dorsal interossei sit. The four dorsal interossei are positioned deepest among the intrinsic palm muscles, lying between adjacent metacarpals. Their placement between the metacarpals places them in the fourth, or deepest, layer of the palm’s muscular plan. Because of this, they occupy the fourth layer rather than the more superficial layers. These muscles act to abduct the fingers away from the middle finger and are innervated by the deep branch of the ulnar nerve.