Question

multiple choice question

which muscle works with the pectoralis minor to draw the scapula laterally and forward around the chest wall, and acts as the prime mover in all forward-reaching and pushing actions?

serratus anterior
trapezius
erector spinae
pectoralis major

Explanation:

Analyze the functional requirements

The question asks for a muscle that works synergistically with the pectoralis minor to draw the scapula laterally and forward around the chest wall (protraction). It also specifies that this muscle acts as the Prime Mover in all forward-reaching and pushing actions (often referred to as the "boxer's muscle").

Evaluate the anatomical options

• Serratus anterior: This muscle originates on the superolateral surfaces of the upper ribs and inserts along the entire anterior length of the medial border of the scapula. Its primary action is to protract and hold the scapula against the thoracic wall, acting as the prime mover in pushing and reaching forward.
• Trapezius: This muscle primarily retracts (draws back), elevates, and depresses the scapula, which is antagonistic to the forward-reaching action.
• Erector spinae: This is a deep muscle group of the back responsible for extending and laterally bending the vertebral column, not moving the scapula.
• Pectoralis major: While involved in flexion, adduction, and medial rotation of the humerus at the shoulder joint, it is not the prime mover for drawing the scapula laterally and forward around the chest wall.

Identify the correct muscle

The serratus anterior works as a Synergist Muscle Function alongside the pectoralis minor to protract the scapula, and is the key prime mover for pushing and reaching movements.

Answer:

• (A) Serratus anterior (Correct answer)
• (B) Trapezius
• (C) Erector spinae
• (D) Pectoralis major