168 HUMAN PHYSIOLOGY. 



Sensory nerve of the pharynx ; glosso-pharyngeal or 9th pair. 



Sensory nerves of the lungs, stomach, etc.; pneumogastric or roth 



pair. 



Length of spinal cord; i6to 1 8 inches, weight i^ ounces. 

 Point of decussation of motor fibres ; at the medulla oblongata. 

 Point of decussation of sensory fibres ; throughout the spinal cord. 

 Function of antero-lateral columns of spinal cord ; transmit motor im- 

 pulses from the brain to the muscles. 



Functions of the posterior columns ; assist in the coordination of mus- 

 cular movements. 

 Functions of the medulla oblongata ; controls the functions of insaliva- 



tion, mastication, deglutition, respiration, circulation, etc. 

 Functions of the corpora quadrigemina ; physical centres for sight. 

 Functions of the corpora striata ; centres for motion. 

 Functions of the optic thalami ; centres for sensation. 

 Function of the cerebellum ; centre for the coordination of muscular 



movement. 



Function of the cerebrum ; centre for intelligence, reason and will. 

 Centre for articulate language ; 3d frontal convolution on left side of 



cerebrum. 

 Number of coats to the eye ; three ; 1st, cornea and sclerotic ; 2d, choroid ; 



3d, retina. 



Function of iris ; regulates the amount of light entering the eye. 

 Function of crystalline lens ; refracts the rays of light so as to form an 



image on the retina. 



Function of retina ; receives the impressions of light. 

 Function of membrana tympani ; receives and transmits waves of sound 



to internal ear. 

 Function of Eustachian tube ; regulates the passage of air into and from 



the middle ear. 

 Function of semicircular canals ; assist in maintaining the equipoise of 



the body. 

 Function of the cochlea ; appreciates the shades and combinations of 



musical tones. 



Size of human ovum ; T J^ of an inch in diameter. 

 Size of spermatozoa ; ^^ o f an inch in length. 

 Function of the placenta ; acts as a respiratory and digestive organ for 



the foetus. 

 Duration of pregnancy ; 280 days. 



