16 Questions
What is done after rendering the frog unconscious through stunning?
Pithing to destroy the brain and spinal cord
What is the purpose of pithing in the nerve muscle preparation process?
To destroy the brain and spinal cord
What is the purpose of stunning the frog in the nerve muscle preparation process?
To render the frog unconscious
Where is the pithing needle pushed during the pithing process?
Into the skull and then into the spinal canal
What is done to destroy the brain during pithing?
Pushing the needle anteriorly into the skull
Why are the muscles of the frog's limbs thrown into convulsions during pithing?
Due to destruction of spinal motor neurons
What happens to the limbs of the frog once the cord has been properly destroyed?
They hang down loosely and limply
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
What action indicates that the frog is now 'dead' in the experiment?
Lack of reflex withdrawal of the limbs
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
What happens when branches of the sciatic nerves are snipped away during dissection?
The thigh muscles show twitch-like contractions
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
What action indicates that a piece of vertebral column has been correctly divided into two pieces?
Lifting each piece with forceps
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
What is done after cutting through the fascia covering the thigh muscles?
Separating them with a blunt glass probe
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
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.
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.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
