GENERAL ZOOLOGY 



Stapes in oval window 

 Ossicles < Incus 



Malleus 



Semicircular duct 

 Ampulla 



Vestibule 



Cochlear duct 



of Corti 



Rg. 4.4. The human ear (cf. Figs. 4.17 and 4.18); the lower figure is a cross section of 

 the cochlea. 



nerves, which has branches running to the heart, lungs, and digestive tract. 

 In reptiles, birds, and mammals, eleventh and twelfth pairs of cranial nerves 

 are found. The spinal nerves of vertebrates are continuous with the spinal 

 cord and vary in number according to the number of segments in the vertebral 

 column. The spinal nerves extend to the muscles and skin of the trunk and 

 limbs. The autonomic nerves are of two kinds, the sympathetic and para- 

 sympathetic. The sympathetic nerves originate from that part of the spinal 

 cord located in the thoracic and upper lumbar regions of the vertebral column 

 (see Fig. 4.5). The ganglia which are characteristic of the sympathetic 

 autonomic nerves are located for the most part in paired trunks along each 

 side of the vertebral column. Parasympathetic nerves originate from centers 

 in the midbrain and medulla of the brain and from the spinal cord of the 

 sacral region. Their ganglia are located on or near the organs which they 

 innervate. Autonomic nerves pass to cardiac muscle, to non-striated muscle 

 of blood vessels and coelomic viscera, and to glands. 



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