HEAD, NECK AND SHOULDER GIRDLE 



323 



The topographical relations of the muscles in various regions of the body are 

 illustrated in the series of cross-sections given for each region. 



Tables illustrating the relations of the central nervous system and the per- 

 ipheral nerves to the muscles are given in the section on the nervous system 

 (Section VI). 



Fig. 340.— Human Embryo (Lr) 42 mm. Long. (After His.) 



Auditory sac 

 Bianchial clefts 



Upper limb 



First thoracic myotome 



Sixth thoracic myotome 



First Lumbar myotom.e 





I. MUSCULATURE OF THE HEAD, NECK AND 

 SHOULDER GIRDLE 



PHYSIOLOGIC.\L AND MORPHOLOGICAL ASPECTS 



The head, situated at the anterior end of the trunk in bilaterally symmetrical 

 animals, is prunitivelv that part of the body first brought into contact with new 

 surroundings as the animal moves forward. We therefore find developed here 

 the most highly differentiated organs of special sense, those of vision hearm^, 

 and smell, through which the anima) is put in touch with an environment more pr 

 less removed from immediate contact with the body. In connection with these 



