The caudate nucleus is one of three basic structures that make up the basal ganglia.

It is composed of a head, body and tail. The head of the CN contributes to forming the floor of the lateral ventricle frontal horn. Moreover, the head, which is medially separated by the septum pellucidum, extends beyond the anterior part of the thalamus, stroking the telencephalic cortex. The superior part of the head is covered by the knee of the corpus callosum, while the inferior part is underneath the thalamus and lenticular nucleus, which delimits the internal capsule. The superior part of the body contributes to the formation of the frontal horn of the lateral ventricle, whereas its inferior part is attached to the internal capsule. Finally, the lateral part of the body is attached to the corona radiata, while the medial part is attached to the thalamus. The tail, first travels to the thalamus and back, and then moves below the internal capsule, thereby delimiting the roof of the temporal horn of the lateral ventricle. Finally, the frontal part of the tail thins out and moves to the amygdaloid nucleus. Due to anatomic continuity with the lateral ventricle, internal capsule, lenticular nucleus and thalamus, it is difficult to define anatomic localizations of CN pathologies ¹⁾.

Along with the putamen and globus pallidus, as well in conjunction with the thalamus and two related structures (the substantia nigra and subthalamic nucleus), the caudate nucleus constitutes a system that is responsible largely for voluntary movement.

While this system has long been associated with motor processes due primarily to the basal ganglia’s role in Parkinson’s disease, there is mounting evidence that the structures that make up the basal ganglia—the caudate nucleus included—play important roles in various other nonmotor functions as well.

Organizationally, the interplay between the basal ganglia and various regions in the brain is best described as a series of cortico-striatal loops, in which the striatum receives axons from the cortex (along with the putamen, the caudate nuclei are the main input regions for the basal ganglia), processes the information, then relays this back to distinct cortical regions (hence the name cortico-striatal). The caudate plays an important role in three of these loops: the oculomotor, dorsolateral, and ventral/orbital circuits.

In a related way then, the caudate nucleus has been implicated with voluntary movement, learning, memory, sleep, and social behavior.

The anterior horn of the lateral ventricle (also anterior cornu of the lateral ventricle, frontal horn of the lateral ventricle or precornu) is a portion of the lateral ventricle that passes forward and laterally, with a slight inclination downward, from the interventricular foramen into the frontal lobe, curving around the anterior end of the caudate nucleus.

In order to understand the physiological role of the caudate nucleus, Villablanca combine the laboratory data on cats with reports of patients with selective damage to this nucleus. Cats with bilateral removal of the caudate nuclei showed a stereotyped behavior consisting of persistently approaching and then following a person, another cat, or any object, and attempting to contact the target. Simultaneously, the animals exhibited a friendly disposition and persistent docility together with purring and forelimbs treading/kneading. The magnitude and duration of this behavior was proportional to the extent of the removal reaching a maximum after ablations of 65% or more of the caudate tissue. These cats were hyperactive but they had lost the feline elegance of movements. Additional features of acaudate cats were: (1) postural and accuracy deficits (plus perseveration) in paw usage tasks including bar pressing for food reward; (2) cognitive and perceptual impairments on a T-maze battery of tasks and on the bar pressing tasks; (3) blockage or blunting of the species-specific behavioral response to a single injection of morphine; Unilateral caudate nucleus removal did not produce global behavioral effects, but only deficit in the contralateral paw contact placing reaction and paw usage/bar pressing. Moreover and surprisingly, we found hypertrophy of the ipsilateral caudate nucleus following prenatal focal neocortical removal. The findings in human were also behavioral (not neurological) and also occurred with unilateral caudate damage. The main manifestations consisted of loss of drive (apathy), obsessive-compulsive behavior, cognitive deficits, stimulus-bound perseverative behavior, and hyperactivity. Based on all of the above data he propose that the specific function of the caudate nucleus is to control approach-attachment behavior, ranging from plain approach to a target, to romantic love. This putative function would account well for the caudate involvement in the pathophysiology of a number of clinical syndromes that they mention, all of which compromise approach-attachment- affect behaviors. In addition he conclude that the caudate nucleus contributes importantly to body and limbs posture as well as to the accuracy and speed of directed movements ²⁾.

Vascular supply to the CN relies upon deep perforators from diverse arteries, the two principal ones being the anterior cerebral artery (ACA) and middle cerebral artery (MCA). ACA supplies a part of the CN head:

Recurrent artery of Heubner is responsible for supplying the inferior part of the CN head as well as the adjacent anterior limb of the internal capsule and the subfrontal white matter. From Heubner’s artery, on average four deep perforators arise, having diameters similar to those of the lenticulostriate branches of MCA. ^{3) 4)}.

Furthermore, direct penetrating arteries rom the ACA supply the anterior portion of the CN head ⁵⁾. The medial lenticulostriate arteries originating from the proximal M1 portion of the MCA supply both a small portion of the lateral border of the caudate head and the adjacent internal capsule. The lateral lenticulostriate artery branches, from the mainstream MCA or its superior division branch, supply the largest portion of the CN head, as well as the adjacent internal capsule and the anterior half of the putamen The CN, due to its paraventricular location, is also perfused by ependymal arteries which flow out- ward from the ventricular surface into the cerebral parenchyma ⁶⁾.

CN strokes are classified into:

Caudate nucleus hemorrhage

Caudate nucleus ischemia

The clinical presentation of CN hemorrhage is often characterized by a clinical presentation mimicking subarachnoid hemorrhage, while clinical features of both ischemic and hemorrhagic strokes included behavioral abnormalities dysarthria, movement disorders, language disturbances and memory loss. Most studies to date that have examined vascular CN pathologies have evidenced good outcomes ⁷⁾.