muscle



Menu

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