311
CHAPTER NINE
Muscular System
vertebral column, and the lower f
bers draw the scapula and
shoulder downward. When other muscles f
x the shoulder in
position, the trapezius can pull the head backward or to one
side (see f
g. 9.24).
Rhomboid
(rom-boid
)
major
and
minor
connect the
vertebral column to the scapula. Both retract and elevate the
scapula. Rhomboid major can also rotate the scapula down-
ward (see f
g. 9.27).
The
trapezius
(trah-pe
ze-us) is a large, triangular mus-
cle in the upper back that extends horizontally From the base
oF the skull and the cervical and thoracic vertebrae to the
shoulder. Its f bers are organized into three groups—upper,
middle, and lower. Together these f bers rotate the scapula.
The upper f bers acting alone raise the scapula and shoulder,
as when the shoulders are shrugged to express a Feeling oF
indiFFerence. The middle f bers pull the scapula toward the
Trapezius
Trapezius
Deltoid
Deltoid
Latissimus dorsi
Levator scapulae
Supraspinatus
Infraspinatus
Teres minor
Teres major
Rhomboid major
Rhomboid minor
Latissimus
dorsi
Rhomboid
major
Rhomboid
minor
(a)
(d)
(c)
(b)
FIGURE 9.27
Muscles of the shoulder and back. (
a
) Muscles of the posterior shoulder. The right trapezius is removed to show underlying muscles.
Isolated views of (
b
) trapezius, (
c
) deltoid, and (
d
) rhomboid and latissimus dorsi muscles.
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