Question
Correctly identify and label the structures associated with two descending pathways of the CNS.
it also known as the precentral gyrus
fibers running through this structure include the corticospinal tract and the corticobullar tract
it is formed by the corticospinal tracts
it is the crossing over of the corticospinal fibers
deficits will be contralateral
choices:
decussation in medulla
anterior corticospinal tract
decussation in spinal cord
motor cortex
lateral corticospinal tract
medullary pyramid
cerebral peduncle
it also known as the precentral gyrus
fibers running through this structure include the corticospinal tract and the corticobullar tract
it is formed by the corticospinal tracts
it is the crossing over of the corticospinal fibers
deficits will be contralateral
choices:
decussation in medulla
anterior corticospinal tract
decussation in spinal cord
motor cortex
lateral corticospinal tract
medullary pyramid
cerebral peduncle
Answers
GPT-4o mini
Here are the correct identifications and labels for the structures associated with the two descending pathways of the CNS:
1. **Motor cortex**: This structure is also known as the precentral gyrus and is where the primary motor cortex is located.
2. **Lateral corticospinal tract**: Fibers running through this structure include the corticospinal tract, which is responsible for voluntary motor control.
3. **Medullary pyramid**: This structure is formed by the aggregation of corticospinal tracts. It is involved in the crossing over of the corticospinal fibers.
4. **Decussation in medulla**: This is the crossing over of the corticospinal fibers, which occurs at the junction between the medulla and the spinal cord. This means that deficits will be contralateral (the side of the body that experiences deficits is opposite to the side of the brain where the lesion occurred).
Thus, the relevant structures are:
- **Motor cortex**: Precentral gyrus
- **Lateral corticospinal tract**: Fibers involved in controlling limbs and voluntary movements
- **Medullary pyramid**: Formed by corticospinal tracts
- **Decussation in medulla**: Crossing of corticospinal tracts leading to contralateral deficits
The other options (anterior corticospinal tract, decussation in spinal cord, cerebral peduncle) are less relevant in this context for the specified descending pathways.
1. **Motor cortex**: This structure is also known as the precentral gyrus and is where the primary motor cortex is located.
2. **Lateral corticospinal tract**: Fibers running through this structure include the corticospinal tract, which is responsible for voluntary motor control.
3. **Medullary pyramid**: This structure is formed by the aggregation of corticospinal tracts. It is involved in the crossing over of the corticospinal fibers.
4. **Decussation in medulla**: This is the crossing over of the corticospinal fibers, which occurs at the junction between the medulla and the spinal cord. This means that deficits will be contralateral (the side of the body that experiences deficits is opposite to the side of the brain where the lesion occurred).
Thus, the relevant structures are:
- **Motor cortex**: Precentral gyrus
- **Lateral corticospinal tract**: Fibers involved in controlling limbs and voluntary movements
- **Medullary pyramid**: Formed by corticospinal tracts
- **Decussation in medulla**: Crossing of corticospinal tracts leading to contralateral deficits
The other options (anterior corticospinal tract, decussation in spinal cord, cerebral peduncle) are less relevant in this context for the specified descending pathways.