Structure of brain: The brain of toad is mainly divided into three parts, suchas: fore
brain, mid brain and hind brain.
1. Fore brain: It is the anterior most part of the brain. Brain is the fore brain.The
fore brain is again divided into two parts:
a. Telencephalon b. Diencephalon
A. Telencephalon: It is the anterior most part of the fore brain. It is dividedinto two
parts such as:
a. Olfactory lobe: It is a pair of out growth arising from the telencephalon ofthe fore
brain. These growths are called olfactory lobes. It is the centre of smell of
b. Cerebral hemisphere: Behind the olfactory lobes there are two cerebral hemispheres. Their function is to move the muscles and control
B. Diencephalon: The comparatively small region situated behindtelencephalon is the
diencephalon. Its sides are swollen and there is a narrow raised portion on the
dorsal side. Hormone is secreted from the pituitary body situated here. This
hormone is helpful in metabolic processes, growth, attaining maturity and
nutrition of reproductive cells.
2. Mid brain: The midbrain is situated in between the fore and hind brains Thisregion
is comparatively wider than the other regions. A spherical region present on
the two sides of this part. It is called optic lobe. Midbrain is the centre for
vision of the toad.
3. Hind Brain : The hind brain occupies the posterior position of the mid
brain.This part extends up to the root of the spinal cord. This region of the
brain is divided into two parts. Metencephalon
and Myelencephalon or medulla oblongata.
a. Metencephalon : The narrow part just behind the optic lobes is
themetencephalon. This part controls the voluntray movement of toad.
or Medulla oblongata : It is the posterior
most part ofbrain which gradually narrows and meets with the spinal cord. There
is an aperture behind the cranium. The medulla oblongata comes out through this
aperture and meets the spinal cord. Medulla is an important region of brain. It
assists in physiological functions including capturing of prey, respiration,
producing sound; taking food by tongue, heart beat etc.
The sub-divisions of the brain are given in the following