Final answer:
The deltoid muscle connects the outer clavicle, acromion, and scapular spine to the midpoint of the lateral aspect of the humerus and is responsible for the abduction and movement of the arm.
Step-by-step explanation:
The muscle that runs from the outer clavicle, the top of the acromion, and the scapular spine to the midpoint of the humerus on the lateral aspect is the deltoid muscle. The deltoid is the major abductor of the arm and also assists with flexing and medial rotation, as well as extension and lateral rotation of the arm. It creates the rounded contour of the shoulder and is anchored to the clavicle, acromion, and spine of the scapula, forming a V-shaped attachment that allows for various movements of the arm.
The deltoid is a thick muscle that creates the rounded lines of the shoulder and is the major abductor of the arm. It also facilitates flexing, medial rotation, extension, and lateral rotation of the arm.