7 i6 THE BASAL GAXtiLIA. 



ventricular portion, the lenticular nucleus. Between the head of the caudate 

 nucleus internally, and the lenticular nucleus externally, lies the anterior division 

 of the internal capsule. The fibres which pass between these ganglia do not 

 seem to form connections with them. The expanded head of the caudate nucleus 

 is in front, and lies inside and around the front, of the lenticular nucleus, with 

 which and the anterior perforated space it is continuous; it sweeps backwards 

 into a tailed extremity, which nearly surrounds the lenticular nucleus like a loop. 

 The lenticular nucleus is biconvex in a horizontal section, but triangular and 

 subdivided into three divisions when seen in a vertical section (fig. 501). The 

 older observations on the corpora striata in man may be dismissed, as a distinction 

 was not drawn between injury to its two parts on the one hand and the internal 

 capsule on the other.] 



[The caudate nucleus and lenticular nucleus in their development are co- 

 ordinate with the development of the cortex cerebri. Electrical stimulation of 

 these ganglia causes general muscular contractions in the opposite half of the body, 

 which are due to simultaneous stimulation of the neighbouring cortico-muscular 

 paths. The same result is obtained as if all the motor cortical centres were stimu- 

 lated simultaneously.] 



Gliky did not observe movements on stimulating the corpus striatum in rabbits ; it would 

 seem that, in these animals the motor paths do not traverse these ganglia, but merely pass along- 

 side of them. 



[Lesions of the lenticular nucleus or of the caudate nucleus do not seem to give 

 rise to any permanent symptoms, provided the internal capsule be not injured.] 

 Destruction of the internal capsule, however, causes paralysis of motion or 

 sensibility, or both, on the opposite side of the body, according to the part of it 

 which is injured. The corpus striatum is quite insensible to painful stimulation 

 (Longet). 



Pathological. Iu man, a lesion, not too small, destroying the anterior part of the corpus 

 striatum is followed by permanent paralysis of the opposite side, provided the internal capsule 

 is injured, but the paralysis gradually disappears, if the lenticular and caudate nucleus only are 

 affected (compare 365). Sometimes there is dilatation of the blood-vessels in consequence of 

 vaso-motor paralysis ( 377) if ,the posterior part is injured (Nothnagel) ; redness and a slightly 

 increased temperature of the paralysed extremities, at least for a certain time ; swelling or 

 oedema of the extremities ; sweating ; anomalies of the pulse detectable by the sphygmograph ; 

 decubitus acutus on the paralysed side ; abnormalities of the nails, hair, skin ; acute inflamma- 

 tions of joints, especially of the shoulder. Later, contracture or permanent contraction of the 

 paralysed muscles takes place (ffuguenin, Cliarcot). In some cases there is cutaneous anaesthesia, 

 and occasionally enfeeblement of the sense-organs of the paralysed side, and both when the 

 posterior third or sensory cross way of the posterior section of the internal capsule is affected. 

 Usually, however, hemiplegia and hemianccstlicsia occur together. 



Optic Thalamus. Ferrier did not observe any movements on stimulating the 

 optic thalami with electricity. As the pulvinar, or posterior extremity of the optic 

 thalamus, is in part the origin of the optic nerve, and is also connected by fibres 

 with the cortex cerebri, it is probably related to the sense of sight. Injury to its 

 posterior third in man, results in disturbance of vision (Nothnagel). Ferrier 

 surmises that the sensory fibres pass through the optic thalami on their way to the 

 cortex, so that when they are destroyed, insensibility of the opposite half of the 

 body is produced. Removal of the optic thalamus, or destruction of the part in 

 the neighbourhood of the inspiratory centre in the wall of the third ventricle, 

 influences the co-ordinated movements in the rabbit (Christiani). 



We know very little definitely as to the functions of these organs. After injury to one 

 thalamus, there has been observed enfeeblement or paralysis of the muscles of the opposite side, 

 together with mouvements de manege ; and sometimes hemianesthesia of the opposite side, 

 with or without affections of the motor areas, have been recorded. Extirpation of certain 

 cortical areas (rabbit) is followed by atrophy of certain parts of the thalamus (v. Monakow). 



[Internal Capsule. In connection with the functions of the basal ganglia, it is 

 most important to remember their relation to the internal capsule. The corpus 



