496 Animal Biology 



(c) Receptors for equilibrium located in the inner ear (Fig. 250). 

 The semicircular canals, which are hollow and hairlined, con- 

 tain fluid. Three canals in each inner ear are all at rie^ht ans^les 

 to one another in three different planes. Movement of the fluid 

 stimulates the hairs, giving a sensation of movement. The sac- 

 cule and utricle arc hollow or^i^ans lined with sensitive hairs and 

 contain solid granules of calcium carbonate called otoliths. 



LOnCITUOItlAL FISSURE 



FROMTAL LOBE 



OPTIC CHIASMA 



TEMPOR 

 LOBE 



STALK OF 

 HYPOPHYSI 



OPTIC 

 TRACT- 



CER 

 PEDUMCL 



MAMMILL 

 BODY 



POfIS 



PYRAMID 



CEREBELLUM 



MED 

 OBLOMGATA 



$PmAL CORD 

 OCCIPITAL LOBE 



I. OLFACTORY 



2. OPTIC 



3 OCULOMOTOR 



4. TROCHLEAR 



5(TRIGEMIt1AL MOTOR 

 (.TRIGEMItlAL SEnSORY 



6. ABDUCENT 



7 FACIAL 



IflTERMEDIATE 

 6 ACOUSTIC 



9. GLOSSOPHARYtlGEAL 



10. VAGUS 



I. SPIMAL ACCESSORY 



2. HYPOGLOSSAL 



Fig. 247. — Human brain, from undcrsurface, with parts labeled and the twelve 

 cranial nerves listed on the right. (From Zoethout and Tuttle: Textbook of 

 Physiology, The C. V. Mosby Co.; after Morat.) 



Head movements cause the latter to stimulate the hairs, giving 

 a sensation of position. 

 (d) Proprioceptors (L. propricta, property, condition), peripheral 

 receptors of the afferent nerves in muscles, tendons, joints, which 

 assist in the complex coordinated movements in locomotion and 

 posture (kinesthetic sense). 



