Which muscles primarily facilitate upward rotation when the arm is elevated over 120 degrees?

Which muscles primarily facilitate upward rotation when the arm is elevated over 120 degrees?

• A. Upper trap and infraspinatus
• B. Lower trap and serratus anterior
• C. Rhomboids and supraspinatus
• D. Pectoralis major and minor

Answer: (B)

The choice that indicates lower trapezius and serratus anterior as the primary facilitators of upward rotation when the arm is elevated over 120 degrees is correct. The upward rotation of the scapula is essential for the full elevation of the arm, especially past 120 degrees, as it allows for optimal positioning of the glenoid cavity relative to the humerus. The lower trapezius plays a crucial role by providing a stabilizing force that helps to depress and rotate the scapula upward. This muscle assists in maintaining the scapula's position against the ribcage, allowing for a full range of motion when the arm is raised. Meanwhile, the serratus anterior works in conjunction with the lower trapezius to produce this movement. Its primary function is to protract and stabilize the scapula against the thoracic wall, and it is particularly important for activating that upward rotation during arm elevation. This collaboration between the two muscles enables efficient overhead movement, which is critical in many functional activities. Understanding the synergy between these muscles helps in diagnosing and treating shoulder pathologies, particularly those related to movement dysfunctions in overhead athletes or individuals with shoulder impairments.

The choice that indicates lower trapezius and serratus anterior as the primary facilitators of upward rotation when the arm is elevated over 120 degrees is correct.

The upward rotation of the scapula is essential for the full elevation of the arm, especially past 120 degrees, as it allows for optimal positioning of the glenoid cavity relative to the humerus. The lower trapezius plays a crucial role by providing a stabilizing force that helps to depress and rotate the scapula upward. This muscle assists in maintaining the scapula's position against the ribcage, allowing for a full range of motion when the arm is raised.

Meanwhile, the serratus anterior works in conjunction with the lower trapezius to produce this movement. Its primary function is to protract and stabilize the scapula against the thoracic wall, and it is particularly important for activating that upward rotation during arm elevation. This collaboration between the two muscles enables efficient overhead movement, which is critical in many functional activities.

Understanding the synergy between these muscles helps in diagnosing and treating shoulder pathologies, particularly those related to movement dysfunctions in overhead athletes or individuals with shoulder impairments.