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Chapter 7: The Muscular System
Muscles of the Pectoral Girdle and Upper Limbs
LEARNING OBJECTIVES
Identify the muscles of the pectoral girdle and upper limbs
Identify the movement and function of the pectoral girdle and upper limbs
Muscles That Position the Pectoral Girdle
Muscles That Move the Humerus
Muscles That Move the Forearm
Muscles That Move the Wrist, Hand, and Fingers
Muscles of the Arm That Move the Wrists, Hands, and Fingers
Intrinsic Muscles of the Hand
Muscles of the shoulder and upper limb can be divided into four groups: muscles that stabilize and position the pectoral girdle, muscles that move the arm, muscles that move the forearm, and muscles that move the wrists, hands, and fingers. The pectoral girdle, or shoulder girdle, consists of the lateral ends of the clavicle and scapula, along with the proximal end of the humerus, and the muscles covering these three bones to stabilize the shoulder joint. The girdle creates a base from which the head of the humerus, in its ball-and-socket joint with the glenoid fossa of the scapula, can move the arm in multiple directions.
Muscles That Position the Pectoral Girdle
Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax (Figure 7.26). The anterior muscles include the subclavius, pectoralis minor, and serratus anterior. The posterior muscles include the trapezius, rhomboid major, and rhomboid minor. When the rhomboids are contracted, your scapula moves medially, which can pull the shoulder and upper limb posteriorly.

Figure 7.26. Muscles That Position the Pectoral Girdle
The muscles that stabilize the pectoral girdle make it a steady base on which other muscles can move the arm. Note that the pectoralis major and deltoid, which move the