46 Dynamic Theory. 



CHAPTER V. 



RUDIMENTS. 



There is further and very striking evidence of the evolution of the 

 higher forms of life from the lower, in the possession, in all of them, of 

 rudimentary organs, so called. These are organs which to their pos- 

 sessors are useless, but which correspond to organs that in other ani- 

 mals are necessary and functional. They are usually' more or less 

 atrophied or reduced in size, and are totally without function, or be- 

 come functionless during the life of their owner. The human ear-shell, 

 for instance, with its muscles, is proved to be totally useless as to the 

 function of hearing. It was developed in the early mammal races as 

 an aid to hearing. It is still useful to the most of them, for they have 

 the power to direct the shell in such a way as to catch a sound more 

 perfectly. But the human race has, from long disuse of the ear mus- 

 cles, almost entirely lost the power to contract them, and so the shell is 

 reduced to a piece of immovable gristle of no use whatever. The ear 

 muscles, whose use has thus been lost, are attollens aurem or levator 

 for raising the ear, attrahens for drawing it forward, retrahens for draw- 

 ing it backward, helicis major for pulling forward the front of the helix, 



FIG. 66. Superficial muscles of head and 

 face. 



1, 2, 3. Occipito frontalis when contracted 

 it raises the eyebrows and wrinkles the fore- 

 head. 



4. Attollens aurem raises the ear in lower 

 animals. 



6. Retrahens aurem draws it back. 

 6. Attrahens aurem draws it forward. 

 7. Tragicus draws forward the tragus or 

 goat. 



8. Superficial part of the masseter pulls up 

 the jaw in chewing. 



9.Zygomatic major \ pull up the upper lip 

 lO.Zygomatic minor j in laughing. 

 11. Orbicularis palpebarum a sphincter 

 around the eye closes the eye (cut off at the 

 right to show No. 12). 



12. Corrugator superciliiit lies under the 

 orbicularis and frontalis (3); it draws the eye 

 brows together and wrinkles the skin. 

 13Pyramidalis nasi wrinkles the skin at 

 the root of the nose, crosswise, and spreads the 

 nostrils. 



14. Compressor naris it either compresses 

 or dilates the nostrils. 

 15. Elevator of the lip and wing of the nose. 

 16. Partly concealed elevator of the corner of the mouth. 

 17. Elevator of the upper lip also pulls it slightly backward. 

 18. Orbicularis ons-surrounds the mouth and closes it. 

 19. Depressor of lower lip. 



20. Elevator of chin ; and pushes up the lower lip. 



2TL.Depressei of corner of the mouth. 22. Buccinator Draws back the mouth. 



23lttsonus or laugher it lengthens the mouth. It is a branch of the next. 

 24;.Platysma myoides. 

 25. Sternocleidomastoid Connects sternum, clavicle andmastoid process. 



helicis minor for contracting the fissure in the cartilage oppgsite the 

 concha, tragicus f or pulling down the tragus or "goat", and the an ti- 

 tragicus belonging to the antitragus. This last muscle is entirely 



