The second mode of extension is the tension of the costal muscles and of the diaphragm, whereby the abdomen is drawn mwards, whilst the abdominal viscera are elevated.
The effect thus aimed at can be particularly clearly observed in
youthful persons, who are
not very fat (Fig. 106).
The tension is tlien increased by a simultaneous contraction of the muscles of the anterior abdominal wall; when those muscles are impaired in their action, e. g. in the case of tight lacing, the lower belly hangs beneath the hollow stomach like an empty sack.
We can see in another photograph (Fig. 107) a doublé action of first and second extension of the dorsal
Fig. 108 Extension of the trunk, supported by extension ot the leg. French wonian of 24.