Question

Midbrain of Frog consists of
A) Corpora quadrigemina
B) Corpora quadrigemina and crura cerebri
C) Two optic lobes and crura cerebri
D) Two optic lobes

Answer 1

Hint: They are responsible for processing of visual information. They serve as bridges that help in connecting the cerebral hemisphere with the opposite half of the cerebellum. It consists of longitudinal bands of nerve fibres.

Complete Answer:
- Midbrain of frogs is small and functions largely as a pathway of nerve tracts between the anterior prosencephalon and the posterior rhombencephalon.
- Midbrain is the contracted region of the brain and it consists of two longitudinal bands of nerve fibres are called as crura cerebri or crus cerebri.
- Crura cerebri are the paired ventro-lateral thickenings of walls and floor. The original dorsal thickening is subdivided by a median into paired dorso-lateral thickenings and they are called optic lobes or corpora bigemina.
- Optic lobes are responsible for the visual information carried out to the brain.

Thus, the correct answer is option C i.e, two optic lobes and crura cerebri.

Additional information: The central nervous system consists of the nerve cord and brain. The brain is enclosed within a bony structure called cranium. The brain is further divided into forebrain, midbrain, hindbrain.
- Forebrain consists of olfactory lobes, unpaired diencephalon, paired cerebral hemispheres.
- Midbrain consists of two optic lobes and crura cerebri.
- Hindbrain consists of medulla oblongata and cerebellum.

Note: Optic lobes perform higher functions related to initiation, memory and control of behaviour. They integrate and process optical data from the eyes and detect various information like movements and shape. Crura cerebri stimulate the muscles controlling.