A transection made at the lower end of medulla through the pyramids would cause all/except:
**Core Concept**
The pyramids of the medulla oblongata contain the corticospinal tracts, which are responsible for motor control and coordination. A transection at the lower end of the medulla through the pyramids would disrupt these tracts, leading to various motor deficits.
**Why the Correct Answer is Right**
A transection through the pyramids would primarily affect the corticospinal tracts, resulting in upper motor neuron lesions. This would lead to spasticity (C) and increased tendon reflexes (D) due to the loss of inhibitory control on the spinal cord. Incoordination (A) would also be a result of this lesion. However, involuntary movements (B) are not typically associated with upper motor neuron lesions, as these are more characteristic of basal ganglia disorders.
**Why Each Wrong Option is Incorrect**
**Option A:** Incoordination is a likely consequence of a pyramidotomy, as it disrupts the corticospinal tracts and leads to difficulties with fine motor control and coordination.
**Option C:** Spasticity is a common result of upper motor neuron lesions, which would occur following a pyramidotomy.
**Option D:** Increased tendon reflexes are also a hallmark of upper motor neuron lesions, such as those caused by a pyramidotomy.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the extent of motor deficits following a pyramidotomy depends on the level and completeness of the lesion. A high or complete lesion would result in more severe and widespread motor deficits.
**✓ Correct Answer: B. Involuntary movements**