Question

What is the main action of the deltoid muscle?

a. Adduction of the arm at the shoulder joint.
b. Retraction of the scapula.
c. Depression of the scapula.
d. Abduction of the arm at the shoulder joint.

Answer 1

The main action of the deltoid muscle is the abduction of the arm at the shoulder joint, making option d the correct answer.

Step-by-step explanation:

The main action of the deltoid muscle is abduction of the arm at the shoulder joint, which corresponds to option d. The deltoid is a thick and powerful muscle that not only abducts the arm but also plays a role in flexion and medial rotation, as well as extension and lateral rotation. Among its functions, the deltoid is also responsible for giving the shoulder its rounded contour.

Answer 2

Option (d).

Step-by-step explanation:

Deltoid muscle forms the rounded contour of the shoulder. This muscle is also known as common shoulder muscle. This muscle is triangle in shape.

Deltoid muscle acts as a prime abductor of the shoulder. This muscle causes abduction of the arms at the shoulder joint of humans. This muscle also involved in the arm extension.

Thus, the correct answer is option (d).