Making "Basal Ganglia/Nuclei" Super easy ;)..

Basal Nuclei refers to the Cell bodies of neurons which are actually present at the base of the brain

Look in the image it shows a section at the base of the brain you will notice certain masses of grey matter , Combined together is what forms the Basal(at the base) Nuclei (Collection of cell bodies of neurons with in the CNS)

NOTE:- Did you noticed the title I mentioned "Basal Ganglia/Nuclei" although Ganglia(cell bodies collection outside CNS) and Nuclei(cell bodies collection within the CNS) have different meanings . It is because the Name - Basal Ganglia is a misnomer and was used in past times the new term is "Basal Nuclei"

Before Moving further let us clear the difference between two more terms :-

1)-Cortex in brain :- it refers to grey matter not surrounded by white matter.

2)-Nuclei :- it refers to Grey matter Surrounded by white matter

Diagramtic view of base of the brain to show some Important relation of Basal ganglia

*Carefully Follow the text and relate it with the upper mentioned image*

A- show you the thalamus

B-is a white matter mass present lateral to the thalamus and we call this white matter mass as "Internal Capsule"

C- is a grey matter mass present lateral to Internal capsules and we call this grey matter mass as "Lentiform Nucleus"

D-White matter mass present lateral to the Lentiform Nucleus which we call as "External Capsule"

E-Grey matter mass present lateral to the External capsule which we call as "Claustrum"

F- White matter mass present lateral to Claustrum which is known as "Extreme Capsule"

G- Grey matter mass present lateral to Claustrum which is known as "Insula" Insula is what you will find at periphery in coronal section of the brain

QUICK FAST SUMMARY OF STRUCTURE FROM THALAMUS TOWARD LATERAL SIDE IN BASE OF BRAIN (Coronal Section)

• Thalamus ---> Internal capsule --> Lentiform Nucleus--> External Capsule-->Claustrum --> Extreme capsule--> Insula

The one mentioned with Brown colour are white matter and others are grey matter.

Now we are left with an interesting grey matter mass which is known as "Caudate nucleus" mentioned as "H" in above image and shown with a orange coloured marker . Now why i called it interesting it is because in 3d it is actually is rat shaped structure

look at the image down below :-

See how the Caudate nucleus start from the end portion of lentiform nucleus that portion of Caudate nucleus is what we call as head of caudate nucleus which takes a turn posteriomedially over the thalamus and that part is body of Caudate Nucleus followed by tail of Caudate nucleus and it terminates in a egg shaped body -"Amygdala"

Last but not the least let's talk about the lentiform (Lens shaped) nucleus now if you closely look at the lentiform nucleus in horizantal section of brain you will find that this grey matter mass is actually divided into sub parts

Division of Lentiform Nucleus

When the researcher cut down the section they noticed that the lateral part of the lentiform nucleus is actually more darker due to more condensed accumulation of cell bodies over there as compared to its medial part and they called this structure as "Putamen" and the less denser portion was called "Globus pallidus" Look the IMAGE BELOW -->

One more thing , there is fine thin band of white matter which actually seperates them and we call it as - "external medullary lamina" . The Globus pallidus is itself divided by another white matter sheet which we call as "internal medullary lamina" (it is present on medial side that's why we call it as internal medullary lamina) and this lamina divides the Globus Pallidus into the :- "Globus pallidus externa" and Globus pallidus interna"

see the lamina in above picture

Contents of basal ganglia

There are many classification under which contents are actually divided

TRADITIONAL CLASSIFICATION - based on the grey matter masses which the scientist noticed when they had cut the section of brain

now try to remind the grey matter masses which we had learnt in relation of basal ganglia part

Thalamus ---> Internal capsule --> Lentiform Nucleus--> External Capsule-->Claustrum --> Extreme capsule--> Insula

so Lentiform Nucleus+ caudate +claustrum = Basal nuclei (although Insula is also grey matter mass observed in section but it is not involved in Basal Nuclei as it is not a nuclei (not surrounded by white matter) it is a actually a part of cortex.

CLINICAL CLASSIFICATION:- this classification includes all those grey matter in the CNS which are connected functionally and term them combindely as Basal Nuclei

It Includes :-

• Caudate
• Lentiform Nucleus
• Substantia Niagra (in Midbrain)
• Subthalamus

This Classification did not involved the amygdala and Claustrum as they are functionally different (Amygdala is a part of limbic system)

NOTE :-

Together Caudate and Lentiform Nucleus (Putamen +Globus Pallidus) Forms = Corpus Striatum but :- Caudate and Putamen (Lateral portion of lentiform nucleus) Forms Striatum.

Embryology and Phylogeny :-

When the researcher studied the structure of this corpus striatum they found that the structure of Putamen(Lateral dark portion of Lentiform nucleus) and caudate was very similar while that of Globus pallidus was different from them , later on a embryological link was found between caudate and putamen and after studies on differnt animal brain it was found that Globus Pallidus portion of basal ganglia was phylogenetically the oldest while the caudate and putamen were modern and developed later on during evolution SO Together Caudate+Putamen forms = Neostriatum (Neo-new) Globus pallidus is called as Paleostriatum (Paleo-older)

mde

Finishing Touches:-

Look at the images below to Connect what you learnt from above given text

Test yourself

Studies have shown that testing your knowledge actually helps the brain to hold the information for a much longer time , let's test some of our knowledge that we have learnt :- Identify the Structure

mde

ANSWERS-->

Functions of Basal Ganglia :-

Although various function (mostly motor) are performed by basal ganglia and i will be uploading a detailed neural circuitary video of basal ganglia (i will update the link when i will upload it ) but from anatomical view just reading the functions is enough (detailed are studied in physiology part)

• Concerned with Planning and Programming of Voluntary movements
• Determine how fast and how large the movements must be (this is what we call as fine tuning)
• Regulates the Muscle tone
• Controls automatic associated movements (swinging of arms during walking).