According to Sherrington model of decerebrate rigidity is characterised by all except
**Core Concept**
The Sherrington model of decerebrate rigidity describes the phenomenon of increased muscle tone and rigidity that occurs after a midbrain transection in cats. This model helps understand the neural mechanisms controlling postural reflexes and muscle tone, particularly the role of the red nucleus and its connections.
**Why the Correct Answer is Right**
In the Sherrington model, decerebrate rigidity is characterized by increased muscle tone, extensor spasms, and a posture of opisthotonus (arching of the back). This is due to the unopposed action of the vestibulospinal and reticulospinal tracts, which are no longer inhibited by the red nucleus. The red nucleus normally acts as an interneuron to inhibit these tracts, but after a midbrain transection, this inhibition is removed, leading to increased muscle tone and rigidity.
**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as this option is missing.
**Option B:** This option is also missing, so we cannot evaluate its correctness.
**Option C:** This is the correct answer, but we will evaluate the other options to provide a complete explanation.
**Option D:** This option is not relevant to the Sherrington model of decerebrate rigidity.
**Clinical Pearl / High-Yield Fact**
The Sherrington model of decerebrate rigidity highlights the importance of the red nucleus in controlling postural reflexes and muscle tone. This knowledge is essential for understanding the neural mechanisms underlying various neurological disorders, such as Parkinson's disease and dystonia.
**Correct Answer: C.**