Applied anatomy and kinesiology, the mechanism of muscular movement . Fig. 32.—Subject lacking righttrapezius, trying to hold shoul-ders well back. (Duchenne.) 66 MOVEMENTS OF THE SHOULDER GIRDLE upward rotation would be produced. The reader will be interestedto watch this point as our study progresses. Since the trapezius lies immediately beneath the skin it is com-paratively easy to test its action in various movements by observ-ing the thickening and hardening of its fibers during shown in Fig. 34 the lower three parts show this effect plainly,the upper part indistinctly. The
Applied anatomy and kinesiology, the mechanism of muscular movement . Fig. 32.—Subject lacking righttrapezius, trying to hold shoul-ders well back. (Duchenne.) 66 MOVEMENTS OF THE SHOULDER GIRDLE upward rotation would be produced. The reader will be interestedto watch this point as our study progresses. Since the trapezius lies immediately beneath the skin it is com-paratively easy to test its action in various movements by observ-ing the thickening and hardening of its fibers during shown in Fig. 34 the lower three parts show this effect plainly,the upper part indistinctly. The upper part of the trapezius illus-trates well why it is necessary to study the muscles on the Fig. -Abnormal posture of right scapula due to loss of the right trapezius.(Mollier.) We have noticed that the first part of the trapezius is admirablysituated for lifting the shoulders, and that when it is stimulated byelectric current it does so promptly. When we shrug the shoulders,therefore, it is natural to infer that it aids in the movement, butobservation of the kind we are considering now shows that it doesnothing of the kind, remaining in complete relaxation while themovement is being performed. To prove this we need only to press the tips of two fingers down TRAPEZIUS 67 behind the outer third of the clavicle and then, while they arethere, to shrug the shoulders. The first part of the trapezius notonly fails to lift the fingers out from behind the clavicle but wecan remove the fingers, while the shoulders are lifted, and see thedeep pocket remaining there. To notice how actual contractionof the muscle affects it, raise the arm sideward above the level of
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