Frog Muscles Quiz: Physiology Lab Prep with Pithing Needle

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Questions and Answers

What is done after rendering the frog unconscious through stunning?

Pithing to destroy the brain and spinal cord (correct)

Inducing convulsions in the frog's limbs

Blowing on the frog's head again

Dissecting the frog's muscles

What is the purpose of pithing in the nerve muscle preparation process?

To render the frog unconscious

To destroy the brain and spinal cord (correct)

To prepare the frog for stunning

To induce convulsions in the frog's limbs

What is the purpose of stunning the frog in the nerve muscle preparation process?

To destroy the brain and spinal cord

To prepare the frog for dissection

To render the frog unconscious (correct)

To induce reflex and voluntary movements

Where is the pithing needle pushed during the pithing process?

Into the skull and then into the spinal canal Signup and view all the answers

What is done to destroy the brain during pithing?

Pushing the needle anteriorly into the skull Signup and view all the answers

Why are the muscles of the frog's limbs thrown into convulsions during pithing?

Due to destruction of spinal motor neurons Signup and view all the answers

What happens to the limbs of the frog once the cord has been properly destroyed?

They hang down loosely and limply Signup and view all the answers

What is done after cutting through the skin around the trunk below the forelimbs?

Seize the skin in a duster and strip it down to the toes Signup and view all the answers

What action indicates that the frog is now 'dead' in the experiment?

Lack of reflex withdrawal of the limbs Signup and view all the answers

What is done after lifting up the urostyle and seeing the sciatic and other nerves emerging from the vertebral column?

Extend lateral cuts forwards through the hip girdle Signup and view all the answers

What happens when branches of the sciatic nerves are snipped away during dissection?

The thigh muscles show twitch-like contractions Signup and view all the answers

What is the purpose of cutting off the tibia-fibula below the knee joint and the thigh bone just above the point to which the sciatic nerve has been freed?

To complete the dissection and obtain nerve-muscle preparations Signup and view all the answers

What action indicates that a piece of vertebral column has been correctly divided into two pieces?

Lifting each piece with forceps Signup and view all the answers

What indicates that the sciatic nerves have been successfully freed to about 2 cm above the knee joints?

Snipping their branches without causing any muscle contractions Signup and view all the answers

What is done after cutting through the fascia covering the thigh muscles?

Separating them with a blunt glass probe Signup and view all the answers

What should be done after placing a stout all-pin through each knee joint?

Tying a stout thread around the tendon just above the sesmoid bone Signup and view all the answers

Study Notes

Nerve-Muscle Preparation Process

After stunning the frog, it is pithed to destroy the brain and spinal cord.

Pithing Process

Pithing involves pushing a pithing needle through the foramen magnum (hole at the base of the skull) to destroy the brain.
The brain is destroyed to render the frog 'dead' for the experiment.
During pithing, the muscles of the frog's limbs are thrown into convulsions.

Dissection

After cutting through the skin around the trunk below the forelimbs, the urostyle is lifted up to expose the sciatic and other nerves emerging from the vertebral column.
After lifting up the urostyle, the sciatic nerve is freed from the vertebral column.
When branches of the sciatic nerves are snipped away during dissection, the nerve is isolated.

Freeing the Sciatic Nerve

Cutting off the tibia-fibula below the knee joint and the thigh bone just above the point to which the sciatic nerve has been freed allows the nerve to be isolated.
When a piece of vertebral column is divided into two pieces, it indicates that the nerve has been successfully freed.
Freeing the sciatic nerve to about 2 cm above the knee joints indicates successful dissection.

Final Preparations

After cutting through the fascia covering the thigh muscles, the nerves and muscles are exposed.
After placing a stout all-pin through each knee joint, the specimen is ready for experimentation.

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Description

Test your knowledge on the nerve muscle preparation in frogs for the physiology lab. Learn about dissecting techniques, stunning, pithing, and the use of tools like dissecting probe and forceps.

Frog Nerve Muscle Preparation Physiology Lab Quiz