Muscle 3: Appendicular Muscles of the Pectoral Girdle and Upper Limb

Muscle 3: Appendicular Muscles of the Pectoral Girdle and Upper Limb

Topics Covered

Introduction

            Specific actions

            Naming of muscles

Muscles of the pectoral girdle and upper limb

Muscle action during elbow flexion

Introduction

As you have probably observed, muscles can work together or in opposition to accomplish a particular movement. Some movements are highly coordinated and rely on the contraction or relaxation of several muscles. The following terms describes muscles in terms of their role in a particular movement:

·      Prime mover – the muscle that has the main force on a joint

·      Synergist – muscles that assist the prime mover; modifies the direction of movement that occurs

·      Antagonist – muscles that oppose (move the bones in the opposite direction) of the prime mover; preventing excessive movement and injury

·      Fixing – to prevent motion in either direction by contraction of prime movers and antagonists at the same time; prevents movement of bone that prime mover is attached to

Remembering the names of muscles can be tedious and daunting. Therefore, try to use tricks to help yourself remember the name of a muscle by asking yourself these questions:

·      What type of movement is produced (ex. adduction)?

·      What region of the body (ex. Posterior; ex. Brachial)?

·      How many heads?

·      Where is the origin or insertion?

·      What direction do the fascicles run?

·      What shape is the muscle?

Also, see Table 11.2 for a list of mnemonic devices for the Latin roots of muscle terminology.

Muscles of the pectoral girdle and upper limb

Muscles that position the pectoral girdle

·      Figure 11.22

·      Table 11.8

Muscles that move the humerus

·      Figure 11.23

·      Figure  11.24

Muscles that move the forearm

·      Figure 11.25

·      Figure 11.26

Muscles that move the wrist, hand, and fingers

·      Figure 11.27

·      Figure 11.28

·      Table 11.9

Muscle Actions during Elbow Flexion

 (Linked to figure 11.2- Prime Movers and Synergists)

·      Prime mover (agonist) = biceps brachii m.

·      Synergist = brachialis m

·      Antagonist = triceps brachii m.

·      Fixator = muscle that holds scapula firmly in place such as rhomboideus m.