Question

This is the description of general function for five muscles. Some authors say they stabilize the scapula. They include trapezius, levitator scapulae ventral is, rhomboids, pectorals minor, and serratus anterior.

Answer 1

The pectoral girdle is stabilized by muscles located on both the anterior and posterior thorax, including the subclavius, pectoralis minor, serratus anterior, trapezius, levator scapulae, rhomboid major, and rhomboid minor, which position it and enable movement of the arm.

Step-by-step explanation:

Muscles That Position the Pectoral Girdle

The pectoral girdle consists of the clavicle and scapula, providing a stable base for the muscles that move the humerus. The muscles involved in positioning and stabilizing the pectoral girdle are divided between the anterior thorax, comprising the subclavius, pectoralis minor, and serratus anterior, and the posterior thorax, including the trapezius, levator scapulae, rhomboid major, and rhomboid minor. When muscles such as the rhomboids contract, they cause the scapula to move medially, thus affecting the position of the shoulder and upper limb.

Muscles across the shoulder joint that move the humerus include pectoralis major and latissimus dorsi, originating from the axial skeleton, while deltoid, subscapularis, infraspinatus, and others originate on the scapula. These muscles provide movement to the arm and shoulder with various actions such as flexion, extension, abduction, and rotation.

The pectoral girdle muscles are essential for both the stabilization of the shoulder joint and the movement of the upper limbs, ensuring the shoulder joint is a steady platform for other muscles to effect movement of the arm.