FUNCTIONS OF THE INTERNAL CAPSULE. 



535 



are extremely contradictory and fail to throw much light on their functions. 

 Ferrier states that destruction of the posterior part of one thalamus pro- 

 duced blindness in the opposite eye and impairment of the sense of touch 

 and pain in the opposite side of the body. In a patient under the care of 

 Hughlings Jackson there was blindness in the right half of each eye, loss of 

 hearing in the left ear, impairment of taste on the left side of the tongue, 

 and a diminution of the sense of touch on the left side of the body. Post- 

 mortem examination showed a patch of softening in the posterior part of 

 the right thalamus, the remainder of the organ being normal. 



It is probable that in the thalamus visual, tactile, and labyrinthine im- 

 pressions are received, coordinated, and reflected outward, with the result 

 of producing various adaptive motor reactions connected with station and 



FIG. 246. HORIZONTAL SECTION OF THE INTERNAL CAPSULE SHOWING THE POSITION AND 

 RELATION OF THE MOTOR TRACTS FOR THE EYE, HEAD, TONGUE, MOUTH, SHOULDER (Shi.), 

 ELBOW (Elb.), DIGITS OF HAND (Die.), ABDOMEN (Abd.), HIP, KNEE (Kn.), DIGITS OF FOOT 

 (Dig.). S. Sensor tract. O. T. Optic tract. A. T. Auditory tract. 



equilibrium. The thalamus is believed by some investigators to act also as 

 an intermediary between emotional states and their expression in the muscles 

 of the face, this power being lost in certain pathologic conditions. The 

 power of regulating the temperature of the body has been also assigned to 

 the thalamus, as destruction of its anterior extremity is usually followed by 

 a rise in temperature. 



The Internal Capsule. The internal capsule has been shown by the 

 results both of experiment and of pathologic processes to be, first, a pathway 

 for the transmission of nerve impulses from the cerebral cortex to the pons, 

 medulla, and spinal cord, which give rise to contraction of the muscles of the 

 opposite side of the body; and, second, a pathway for the transmission of 

 nerve impulses coming from skin, mucous membrane, muscles, and special 



