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Figure

(a) Muscles of the posterior shoulder. The right trapezius is removed to show underlying muscles. Isolated views of (b) trapezius, (c) deltoid, and (d ) rhomboideus and latissimus dorsi muscles.

The rhomboideus (rom-boid'-e-us) major connects the upper thoracic vertebrae to the scapula. It raises the scapula and adducts it (fig. 9.25).

The levator scapulae (le-va'tor scap'u-le) is a straplike muscle that runs almost vertically through the neck, connecting the cervical vertebrae to the scapula. It elevates the scapula (figs. 9.25 and 9.27).

The serratus anterior (ser-ra'tus an-te're-or) is a broad, curved muscle located on the side of the chest. It arises as fleshy, narrow strips on the upper ribs and ex tends along the medial wall of the axilla to the ventral surface of the scapula. It pulls the scapula downward and anteriorly and is used to thrust the shoulder forward, as when pushing something (fig. 9.26).

The pectoralis (pek"to-ra'lis) minor is a thin, flat muscle that lies beneath the larger pectoralis major. It extends laterally and upward from the ribs to the scapula and pulls the scapula forward and downward. When other muscles fix the scapula in position, the pectoralis minor can raise the ribs and thus aid forceful inhalation (fig. 9.26).

Sternocleidomastoid

Pectoralis minor

Internal intercostal

Serratus anterior

Rectus abdominis

Internal oblique

Transversus abdominis

Sternocleidomastoid

Pectoralis minor

Internal intercostal

Serratus anterior

Rectus abdominis

Transversus abdominis

Figure 9.26

Muscles of the anterior chest and abdominal wall. The right pectoralis major is removed to show the pectoralis minor.

Trapezius

Deltoid

Pectoralis major

Linea alba

(band of connective tissue)

External oblique

Aponeurosis of external oblique

Figure 9.26

Muscles of the anterior chest and abdominal wall. The right pectoralis major is removed to show the pectoralis minor.

Muscles that Move

Essentials of Human Physiology

Essentials of Human Physiology

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