Question

Short-Answer Questions 1. Describe the muscles involved in turning the hand, as when twisting a doorknob back and forth. Name the muscles responsible for flexing the arm. Which muscles are a these flexors? 2. ntagonists to 3. Name a muscle for each movement of the wrist: flex, extend, abduct, and adduct.

Answer 1

1. The actions involved in opening a door are pronation and supination

Pronation requires (anti-clock-wise): Pronator teres and pronator quadratus

Supination requires (clockwise): Supinator muscle

Arm flexors at:

- Shoulder level: Pectoralis major, Anterior deltoid, Coracobrachialisand Biceps brachii

- Forearm level/elbow: Brachialis, Brachioradialii and Biceps brachii

- Wrist level: Flexor carpi radialis, Flexor carpi ulnaris and Palmaris longus

2. Arm Extensors/Antagonists:

-Shoulder level: Triceps brachii

- Forearm level: Brachioradialis, Extensor carpi radialis longus, Extensor carpi radialis brevis and Extensor carpi ulnaris

- Wrist level: Extensor digitorum, Extensor digiti minimi, Extensor carpi ulnaris, Abductor pollicis longus, extensor pollicis brevis, Extensor pollicis longus and Extensor indicis.

3. Flexion: flexor carpi ulnaris, flexor carpi radialis

Extension: extensor carpi radialis longus and brevis, and extensor carpi ulnaris

Abduction: abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus and brevis.

Adduction: extensor carpi ulnaris and flexor carpi ulnaris