Diencephalon

On which sides of the third ventricle is the diencephalon located?

Each side

What are the two major divisions of the diencephalon?

Thalamencephalon and hypothalamus

What structures comprise the thalamencephalon?

Thalamus, metathalamus, epithalamus, and subthalamus

What is the thalamus anatomically?

A large ovoid nuclear complex in the wall of the third ventricle

Where is the thalamus located relative to the interventricular foramen?

Caudal to it

What are the two functional categories of thalamic nuclei?

Specific nuclei and nonspecific nuclei

What are the main functions of specific thalamic nuclei?

Relay and association functions for somatosensory and limbic systems

How are specific thalamic nuclei organized for body representation?

Somatotopically

How do nonspecific thalamic nuclei compare with specific nuclei in size and number?

Smaller and fewer

Which system is associated with nonspecific thalamic nuclei?

Reticular formation

What are the three nuclei of the anterior thalamic group?

Anterior ventral, anterior dorsal, and anterior medial nuclei

What functional type are anterior thalamic nuclei?

Relay nuclei

Which pathway provides input from mammillary bodies to anterior thalamic nuclei?

Mammillothalamic tract

Which cortical gyrus has reciprocal connections with anterior thalamic nuclei?

Cingulate gyrus

Which functional system includes the anterior thalamic group?

Limbic system

What is the principal nucleus of the medial thalamic group?

Mediodorsal nucleus

What functional type is the mediodorsal thalamic nucleus?

Association nucleus

Which systems provide afferents to the mediodorsal nucleus?

Olfactory system, limbic system, globus pallidus, and hypothalamus

Which cortical region has reciprocal connections with the mediodorsal nucleus?

Prefrontal cortex

What does the mediodorsal nucleus link to mood regulation?

Visceral and somatic input

What are the principal association nuclei of the lateral dorsal thalamic group?

Lateral dorsal nucleus, lateral posterior nucleus, and pulvinar

Which cortical and limbic structures are connected with the lateral dorsal nucleus?

Posterior cingulate cortex, amygdala, and parietal cortex

What function is associated with the lateral dorsal nucleus?

Memory

Which sources provide input to the lateral posterior nucleus?

Subcortical visual centers and parietal cortex

What is the pulvinar's role in visual processing?

Association nucleus and relay for the secondary visual pathway

What are the four nuclei of the lateral ventral thalamic group?

Ventral anterior, ventral lateral, ventral posterolateral, and ventral posteromedial nuclei

Which thalamic nuclei receive input from medial globus pallidus, cerebellum, and reticular formation?

Ventral anterior and ventral lateral nuclei

Which cortical areas have reciprocal connections with ventral anterior and ventral lateral nuclei?

Premotor and motor cortex

Which nucleus receives medial lemniscus and spinal lemniscus input?

Ventral posterolateral nucleus

Which thalamic nucleus relays somatic sensation from the body?

Ventral posterolateral nucleus

Which nucleus receives trigeminal lemniscus input?

Ventral posteromedial nucleus

Which thalamic nucleus relays somatic sensation from the face?

Ventral posteromedial nucleus

What cortical target receives output from VPL and VPM?

Somatosensory cortex

Which intralaminar thalamic nucleus receives input from cerebellum, reticular formation, and medial globus pallidus?

Centromedian nucleus

What is the major efferent target of the centromedian nucleus?

Neostriatum

Which connection is provided by the centromedian nucleus between cerebellum and striatum?

Cerebellostriatal connection

Which structures form the internal and external thalamic medullary laminae?

Lamina medullaris interna and lamina medullaris externa

What is the thalamic peduncle to the cingulate gyrus called?

Anterior thalamic peduncle

What is another name for the anterior thalamic peduncle?

Radiationes thalami anteriores

Which thalamic nuclei project through the anterior peduncle to the cingulate gyrus?

Anterior nuclei

Which thalamic nuclei project through the anterior peduncle to prefrontal cortex?

Medial nuclei

Which thalamic nucleus projects to premotor cortex through the anterior peduncle?

Ventral anterior nucleus

Which thalamic nucleus projects to motor cortex through the anterior peduncle?

Ventral lateral nucleus

What is another name for the superior thalamic peduncle?

Radiationes thalami centrales

Which thalamic nucleus projects to sensory cortex through the superior peduncle?

Ventral posterolateral nucleus

What is another name for the posterior thalamic peduncle?

Radiationes thalami posteriores

Which thalamic nucleus projects to association areas through the posterior peduncle?

Pulvinar

Which thalamic nuclei project to corticallimbic areas through the inferior peduncle?

Medial nuclei

What is the auditory thalamic nucleus?

Medial geniculate body

Which brachium connects the inferior colliculus with the medial geniculate body?

Brachium of the inferior colliculus

Which ascending auditory tract provides input to the medial geniculate body?

Lateral lemniscus

What are the two cellular parts of the medial geniculate body?

Parvocellular and magnocellular parts

What pathway carries medial geniculate output to auditory cortex?

Auditory radiation

What is the principal thalamic nucleus for vision?

Lateral geniculate body

What pathway carries retinal input to the lateral geniculate body?

Optic tract

Does the lateral geniculate body receive input from one or both eyes?

Both eyes

What cortical area receives lateral geniculate output?

Primary visual cortex

How many layers does the lateral geniculate body have?

Six

Which layers of the lateral geniculate body receive ipsilateral retinal input?

Layers 2, 3, and 5

Which layers of the lateral geniculate body receive contralateral retinal input?

Layers 1, 4, and 6

How is visual space represented in the lateral geniculate body?

Retinotopically

What pathway carries lateral geniculate output to visual cortex?

Optic radiation

Which midbrain structure receives lateral geniculate efferents?

Superior colliculus

Which visual reflex center receives lateral geniculate efferents?

Pretectal area

Which homeostatic structure receives lateral geniculate efferents?

Hypothalamus

What are the three anteroposterior regions of the hypothalamus?

Anterior, middle, and posterior hypothalamus

What is another name for the anterior hypothalamic region?

Supraoptic region

What landmark corresponds to the anterior hypothalamic region?

Optic chiasm

What is another name for the middle hypothalamic region?

Tuberoinfundibular region

What structures correspond to the middle hypothalamic region?

Tuber cinereum and infundibulum

What is another name for the posterior hypothalamic region?

Mammillary region

What structure corresponds to the posterior hypothalamic region?

Mammillary body

What are the three mediolateral zones of the hypothalamus?

Periventricular, intermediate medial, and lateral zones

Which hypothalamic zone contacts the medial forebrain bundle?

Lateral zone

What type of fibers reach hypothalamus and cortex through the medial forebrain bundle?

Aminergic fibers

What are the major nuclei of the anterior hypothalamic group?

Supraoptic, paraventricular, preoptic, and suprachiasmatic nuclei

What are the major nuclei of the middle hypothalamic group?

Dorsomedial tuberal, ventromedial tuberal, lateral tuberal, and infundibular nuclei

What are the major nuclei of the posterior hypothalamic group?

Mammillary and posterior hypothalamic nuclei

Where is the supraoptic nucleus located?

Above the lateral part of the optic chiasm

What hormone is synthesized by large supraoptic-nucleus neurons?

Vasopressin

Which tract carries supraoptic-nucleus axons to the posterior pituitary?

Supraoptico-hypophyseal tract

Where is the paraventricular nucleus located?

Along the medial side of the fornix from the hypothalamic sulcus

Which tract carries paraventricular-nucleus axons to the posterior pituitary?

Paraventriculo-hypophyseal tract

Which hormones are produced by magnocellular paraventricular neurons?

Vasopressin and oxytocin

Which anterior hypothalamic nuclei regulate day-night cycles?

Preoptic and suprachiasmatic nuclei

Which hypothalamic nucleus is most associated with circadian rhythms?

Suprachiasmatic nucleus

Which functions are regulated by preoptic and suprachiasmatic nuclei?

Motor activity, body temperature, hormone concentration, renal secretion, sleep, and wakefulness

What retinal input reaches the anterior hypothalamic nuclei?

Collaterals of the optic tract

Which thalamic nuclei provide input to anterior hypothalamic nuclei?

Midline nuclei

Which pathways convey limbic input to anterior hypothalamic nuclei?

Medial forebrain bundle and stria terminalis

Which pathway connects anterior hypothalamic nuclei with parasympathetic nuclei and brainstem reticular formation?

Dorsal longitudinal fasciculus

What is the posterior-pituitary output tract of anterior hypothalamic nuclei?

Supraoptico-hypophyseal tract

What are the nuclei tuberales?

Small neurosecretory nuclei between tuber cinereum and mammillary body

What type of hormones are produced by tuberal nuclei for the anterior pituitary?

Releasing hormones

Which mediator produced by tuberal nuclei inhibits prolactin secretion?

Dopamine

What is another name for the infundibular nucleus?

Arcuate nucleus

Where does the infundibular nucleus cross the midline?

Infundibulum

Which systems provide afferents to the middle hypothalamic group?

Limbic system and brainstem

Which tract carries middle hypothalamic output to the anterior pituitary?

Tubero-infundibular tract

Where do tubero-infundibular fibers terminate?

Hypophyseal portal vessels in the infundibulum