Theory:

II. Midbrain:
midbrain.jpg
The cross section of brain
 
Location: Between the thalamus/hypothalamus of the forebrain and pons of the hindbrain.
 
Cerebral aqueduct, a canal, passed through the midbrain.
 
Midbrain is composed of  corpora quadrigemina and crura cerebri.
  1. Corpora quadrigemina has two parts: (i) Superior colliculi - controls visual reflexes (ii) Inferior colliculi - controls auditory (hearingreflexes
  2. Crura cerebri relay impulses back and forth between the cerebrum, cerebellum, pons and medulla.
III. Hindbrain:
Hindbrain act as control centres for many of the involuntary actions, and it consists of following parts,
  
Cerebellum:
  
It is the second largest part of the brain, next to cerebrum. It has,
  1. Two large sized hemispheres
  2. Middle vermis
It consists of highly convoluted surface to provide additional space for more neurons. It is responsible for maintaining the posture and balance of the body while doing voluntary actions such as walking on a narrow column, riding a bicycle, picking up a pen. The cerebellum also controls the precision of these voluntary actions.
  
Pons or Pons varolii:
  
Pons - latin word meaning " bridge". It is present below the midbrain consists of bridge of nerve fibre tracts that interconnect different lobes of the brain. It act as a relay centre between cerebellum, spinal cord, midbrain and cerebrum. This region mainly regulates the respiration and sleep cycle.
  
Medulla oblongata:
  
It is also called as medulla and is the posterior most part of the brainconnected to spinal cord. It has
  1. Respiratory control centre - controls respiration
  2. Cardiac centre - controls heartbeat
  3. Vasomotor center - controls contractions of blood vessels
Salivation, maintaining of blood pressure and vomiting are some of the involuntary actions controlled by the medulla in the hindbrain.
  
Important!
Note: When individuals drink alcohol, it affects the cerebellum, which causes changes in movement and balance. This is the reason that drunk persons are more prone to collapse or have impaired speech.
Brainstem:
Blausen_0114_BrainstemAnatomy.png
Parts of  the brain stem
 
It connects the brain to the spinal cord.. It is responsible for autonomic control of activities such as respiration and heart rate, as well as information transmission to and from the peripheral nervous system, which includes nerves and ganglia outside the brain and spinal cord. It is the place of entry or exit for ten of twelve cranial nerves. It is composed of,
  1. Diencephalon
  2. Medulla oblongata
  3. Pons varolii
  4. Mid brain
Grey matter and white matter:
  • The cell bodies and dendrites of neurons, as well as supporting cells called astroglia and oligodendrocytes, make up grey matter.
  • White matter, on the other hand, is largely made up of axons that are wrapped in myelin.
  • Grey matter neurons do not have long axons, unlike white matter neurons.
  • Grey matter accounts for \(40% \)of the brain's volume, whereas white matter accounts for \(60%\).
  • Grey matter gets its colour from the grey nuclei that constitute the cells. The white appearance of the white matter is due to myelin.
  • Grey matter completes processing, whereas white matter facilitates communication between grey matter regions and between grey matter and other parts of the body.
  • Grey matter does not have a myelin coating, but white matter possesses it.
Important!
Myelin is an insulating substance that helps cells transport messages faster, and it is responsible for the white matter's lighter colour.
unnamed (1).jpg
Grey and white matter in the brain
Overview of brain functions:
Structure
Functions
Cerebral cortexSensory perceptions, control of voluntary functions, language, thinking, memory, decision making, creativity
ThalamusActs as relay station
HypothalamusTemperature control, thirst, hunger, urination, important link between nervous system and endocrine glands
CerebellumMaintenance of posture and balance, coordinate voluntary muscle activity
Pons and medullaRole in sleep-awake cycle, cardiovascular, respiratory and digestive control centers

Nearly \(60\)% of the human brain made up of is fat. Essential Fatty Acids (EFAs) are crucial substances that determine the integrity and ability of our brain.

Food is the only way to get EFAs because our bodies can't synthesise them. EFAs are abundant in fish, green leafy vegetables, almonds and walnuts.

The electroencephalogram (Gbe) is a device that records electrical impulses in the brain. EEGs can detect abnormalities in brain waves and aid in diagnosing seizures, epilepsy, brain tumours and head injuries, among other conditions.

Reference:
https://upload.wikimedia.org/wikipedia/commons/8/83/Diagram_showing_the_brain_stem_which_includes_the_medulla_oblongata%2C_the_pons_and_the_midbrain_%282%29_CRUK_294.svg
https://upload.wikimedia.org/wikipedia/commons/e/e0/Blausen_0114_BrainstemAnatomy.png
https://upload.wikimedia.org/wikipedia/commons/thumb/a/af/1202_White_and_Gray_Matter.jpg/512px-1202_White_and_Gray_Matter.jpg