Fig. 40.
Fig. 40. A lateral view of the muscles of the trunk. 3, The upper part of the external oblique muscle. 4, Two of the external intercostal muscles. 5, Two of the internal intercostals. 6, The transversalis muscle. 7, Its posterior aponeurosis. 8, Its anterior aponeurosis. 11, The right rectus muscle. 13, The crest of the ilium, or haunch-bone.
Practical Explanation. The rectus muscle, 11, bends the thorax upon the abdomen when the lower extremity of the muscle is the fixed point; but when the upper extremity is the fixed point, the effect is to bring forward and raise the pelvis and lower extremities. They likewise depress the ribs in respiration. The transverse muscle, 6, 7, 8, lessens the cavity of the abdomen, and presses the intestines; stomach, and liver upward, against the diaphragm, in expiration.
3d. The region of the back, in consequence of its extent, is common to the neck, the upper extremities, and the abdomen. The muscles of which it is composed are numerous, and are arranged in six layers.
What is represented by fig. 40? Give the function of some of the muscles represented by this figure.
Fig. 41.
