Where do most fibers decussate in the lateral corticospinal tract? Pons. Spinal cord. Medulla oblongata. Thalamus.

Breakdown of the Problem

To determine where most fibers decussate in the lateral corticospinal tract, we need to evaluate the major parts of the central nervous system and identify the site where decussation occurs.

Relevant Concepts

The lateral corticospinal tract is a descending motor pathway that originates in the cerebral cortex and is crucial for voluntary motor control. The decussation refers to the crossing over of nerve fibers to the opposite side of the body.

Analysis and Detail

1. Cerebral Cortex: The fibers of the corticospinal tract originate from the motor cortex in the cerebral cortex.
2. Medulla Oblongata: The major crossing, known as the pyramidal decussation, occurs here. Approximately 90% of the fibers cross over to the contralateral side at this level.
3. Spinal Cord: After decussating in the medulla, the fibers travel down the spinal cord as the lateral corticospinal tract.
4. Pons and Thalamus: Fibers pass through the pons and also project to the thalamus, but these areas are not where the majority of decussation occurs.

Verify and Summarize

Based on the anatomy and the pathway of the corticospinal tract, the correct site for the majority of fibers to decussate is at the medulla oblongata.

Final Answer

Medulla oblongata.