The shoulder girdle muscles can move the humerus/shoulder joint. Group of answer choices True False
The correct answer and explanation is:
Correct Answer: False
Explanation:
The shoulder girdle muscles (also called scapular muscles) do not directly move the humerus or shoulder joint. Instead, they function to move and stabilize the scapula (shoulder blade), which provides a stable base for humeral motion.
The shoulder girdle includes bones like the scapula and clavicle, and it articulates with the axial skeleton at the sternoclavicular joint. The main muscles of the shoulder girdle include:
- Trapezius
- Levator scapulae
- Rhomboid major and minor
- Serratus anterior
- Pectoralis minor
These muscles are primarily responsible for movements such as elevation, depression, retraction, protraction, and rotation of the scapula. These motions are critical because shoulder (glenohumeral) joint function depends heavily on the position and motion of the scapula. However, the shoulder girdle muscles themselves do not attach directly to the humerus, so they cannot cause movement at the shoulder joint (glenohumeral joint) directly.
In contrast, shoulder joint muscles, such as the deltoid, pectoralis major, latissimus dorsi, teres major, and the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis), do insert on the humerus and are responsible for its movement — such as flexion, extension, abduction, adduction, internal and external rotation.
Therefore, while the shoulder girdle muscles play a supportive and stabilizing role, particularly by controlling scapular motion, they do not directly move the humerus at the shoulder joint, which makes the correct answer False.