EX 2 LAB muscle tonus

• Muscle tonus refers to a state of slight muscular contraction maintained by synchronous impulses of low frequency, discharged by the spinal motor neurons
• Muscle tonus is reflex in nature
• When the spinal cord is transected, there is immediate paralysis of the flaccid types involving the muscles below the point of section
• The limbs of the frog in the experiment would hang limply, the muscles being quite toneless, which is called SPINAL SHOCK
• The duration of spinal shock varies according to animal species, with higher animals experiencing more profound shock and slower recovery
• Cutting the roots of the right sciatic nerve results in the right lower limb of the frog becoming limp, as the connections with the spinal cord are removed
• The right gastrocnemius muscle becomes flabby while the left gastrocnemius muscle remains firm due to intact connections with the spinal cord
• When the spinal cord is destroyed, both lower limbs hang limply, indicating that impulses responsible for maintaining muscle tonus are located in the spinal cord, specifically the spinal motor neurons
• Spinal shock is attributed to the sudden cessation or removal of impulses from higher cortical centers that reinforce the spinal centers
• Recovery from spinal shock may be due to the development of denervation hypersensitivity to chemical mediators released by the remaining spinal excitatory endings
• Muscle tonus is important for governing posture, maintaining bodily balance, and facilitating and coordinating body movements, whether simple or complex