a. Name two forearm muscles that are powerful extensors and abductors of the hand. b. Name the sole forearm muscle that can flex the distal interphalangeal joints.

Verified step by step guidance

1. Step 1: Identify the muscles involved in the extension and abduction of the hand.
2. Step 2: Recognize that the extensor carpi radialis longus and extensor carpi radialis brevis are key muscles for extension and abduction of the hand.
3. Step 3: Understand that these muscles are located in the posterior compartment of the forearm and are innervated by the radial nerve.
4. Step 4: For the flexion of the distal interphalangeal joints, identify the muscle responsible for this action.
5. Step 5: Note that the flexor digitorum profundus is the sole muscle that can flex the distal interphalangeal joints, as it inserts on the distal phalanges.

Key Concepts

Forearm Muscles

The forearm contains several muscles that are responsible for the movement of the wrist and fingers. These muscles can be categorized into flexors and extensors, with extensors primarily located on the posterior side of the forearm. Understanding the anatomy and function of these muscles is crucial for identifying which ones act as powerful extensors and abductors of the hand.

Extensors and Abductors

Extensors are muscles that increase the angle between body parts, such as straightening the wrist or fingers. Abductors, on the other hand, are responsible for moving a limb away from the midline of the body. In the context of the forearm, certain extensor muscles also contribute to the abduction of the hand, which is essential for various hand movements.

Distal Interphalangeal Joints

The distal interphalangeal (DIP) joints are the joints located between the last two phalanges of the fingers. Flexing these joints allows for gripping and fine motor tasks. The sole muscle capable of flexing the DIP joints is the flexor digitorum profundus, which plays a critical role in hand function and dexterity.