Question

The 5th cranial nerve of a frog is called
(a) Optic nerve
(b) Vagus nerve
(c) Trigeminal nerve
(d) Olfactory nerve

Answer 1

Hint: Frog's nervous system contains 10 pairs of cranial nerves that serve different purposes. These past direct messages from the outside to the brain. With the cranial ones, they also have 10 pairs of spinal nerves to pass information through the spinal cord.

Complete step by step answer:
The fifth cranial nerve of the frog is called the trigeminal nerve which arises from the lateral side of the medulla. The vagus is the 10th cranial nerve and regulates respiration and heart rate and digestive activities. The second nerve is known as the optic which is used for bringing the secondary message from the nose. The first sensory nerve Olfactory brings the message of smell to the nose.

So, the correct answer is ‘Trigeminal’.

Additional Information: The frog’s nervous system has many resemblances with that of the human and is a highly developed system consisting of the brain, nerves, and spinal cord. The brain contains 2 Olfactory lobes, 2 cerebral hemispheres, 1 pineal body, 1 cerebellum, 2 optic lobes, and 1 medulla oblongata. The cerebellum of the hindbrain controls muscular activities and posture whereas the medulla oblongata, the stem-like structure of the brainstem, controls respiration, digestion, etc.
They have 10 pairs of cranial nerves and 10 pairs of spinal nerves and all of them have different roles in different sensory activities.

Note: The cranial nerve pairs of frogs are named below with their origin:

Nerve	Origin
0.Terminal	Forebrain
1.Olfactory	Olfactory lobe
2.Optic	Diencephalon
3.Oculomotor	Midbrain
4.Trochlear	Midbrain
5.Trigeminal	Medulla
6.Abducens	Medulla
7.Facial	Medulla
8.Auditory	Medulla
9.Glossopharyngeal	Medulla