The lower pectoralis major can be stretched by.
Alateral flexion of the spinal column
B maximal hyperflexion of the entire spine
C full abduction of the shoulder
D extreme horizontal adduction of the humerus
The correct answer and explanation is:
The correct answer is D) extreme horizontal adduction of the humerus.
Explanation:
The pectoralis major is a large muscle located in the chest, responsible for movements such as arm flexion, adduction, and internal rotation. It has two main parts: the clavicular (upper) head and the sternal (lower) head. The lower part of the pectoralis major plays a key role in movements like bringing the arm across the body, or in other words, horizontal adduction.
To stretch the lower portion of the pectoralis major, it’s essential to move the arm in a way that elongates this specific muscle segment. Extreme horizontal adduction of the humerus involves moving the arm across the body while keeping the elbow relatively straight or slightly bent, and the upper arm brought toward the opposite shoulder. This motion maximizes the stretch in the lower fibers of the pectoralis major.
Here’s why the other options are incorrect:
- A) Lateral flexion of the spinal column: This movement primarily affects the spine and muscles around the torso, like the obliques and the erector spinae. It does not target the pectoralis major, especially its lower part.
- B) Maximal hyperflexion of the entire spine: Flexing the spine forward can stretch the muscles of the back, but it does not stretch the pectoralis major. The pectoralis major is primarily involved in shoulder and arm movements, not spinal flexion.
- C) Full abduction of the shoulder: While abduction (moving the arm away from the body) stretches the muscles of the shoulder, it does not specifically target the pectoralis major. In fact, the pectoralis major helps with the opposite motion, adduction, and flexion of the arm.
Thus, extreme horizontal adduction of the humerus provides the most effective stretch for the lower portion of the pectoralis major by actively elongating it across the body.