Anatomy #57 Basal ganglia, diencephalon, midbrain

Cerebral White Matter

Second of the three basic regions of cerebral hemispheres

-Responsible for communication between cerebral areas, and between cortex and lower CNS

- Consists of myelinated fibers bundled into large tracts

Basal Nuclei

Third of the three basic regions of cerebrum

Functions of basal nuclei are thought to:

Influence muscle movements

– Play role in cognition and emotion

– Regulate intensity of slow or stereotyped movements

– Filter out incorrect/inappropriate responses

– Inhibit antagonistic/unnecessary movements

Parkinson’s disease and Huntington’s disease are disorders of the

basal nuclei

Diencephalon consists of three paired gray-matter structures:

-Thalamus

– Hypothalamus

– Epithalamus

Thalamus

Bilateral egg-shaped nuclei that form superolateral walls of third ventricle

- Makes up 80% of diencephalon

-Bilateral nuclei connected by interthalamic adhesion

interthalamic adhesion

Contains several nuclei, named for location

– Nuclei project and receive fibers from cerebral cortex

thalamus functions to

Sorts, edits, and relays ascending input such as:

Impulses from hypothalamus for regulating emotion and visceral function

- Impulses from cerebellum and basal nuclei to help direct motor cortices

- Impulses for memory or sensory integration

hypothalamus

• located below thalamus

• Contains many important nuclei such as: – Mammillary bodies:

• main vesceral control & regulating center

Mammillary bodies:

paired anterior nuclei that act as olfactory relay stations

Chief homeostasis controls:

– Controls autonomic nervous system

-Examples: blood pressure, rate and force of heartbeat, digestive tract motility, pupil size

– Initiates physical responses to emotions

the hypothalamas regulates

-body temperature: sweating or shivering

- hunger and satiety in response to nutrient blood levels or hormones

-water balance and thirst

-sleep-wake cycles

hypothalamas controls

endocrine system functions such as:

-Secretions of anterior pituitary gland

-Production of posterior pituitary hormones

Hypothalamic disturbances cause a number of disorders such as:

– Severe body wasting

– Obesity

– Sleep disturbances

– Dehydration

– Emotional imbalances

Can be damaged by tumors, radiation, surgery or trauma

Epithalamus

• Most dorsal portion of diencephalon

- Forms roof of third ventricle

- Contains pineal gland (body)- Secretes melatonin that helps regulate sleep-wake cycle