Toad: Structure of brain

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 toad.

b. Cerebral hemisphere: Behind the olfactory lobes there are two cerebral hemispheres. Their function is to move the muscles and control intelligence.

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.

b. Myelencephalon 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 table: