What is not true about the lateral corticospinal tracts? The fibers descend in the spinal cord to motor neurons that innervate skeletal muscles The fibers provide for subconscious control of skeletal muscles
The correct answer and explanation is:
The statement that is not true about the lateral corticospinal tracts is:
“The fibers provide for subconscious control of skeletal muscles.”
Correct Answer:
The fibers provide for subconscious control of skeletal muscles — ❌ Not true
Explanation (approx. 300 words):
The lateral corticospinal tract is one of the major motor pathways in the central nervous system. It plays a key role in the voluntary control of skeletal muscles, particularly those in the limbs.
These tracts originate from the primary motor cortex in the brain (precentral gyrus), and their fibers decussate (cross over) at the level of the medullary pyramids in the brainstem. After crossing, they descend through the lateral white columns of the spinal cord to synapse with lower motor neurons in the anterior horn of the spinal cord.
Key facts about the lateral corticospinal tracts:
- ✅ They descend in the spinal cord to motor neurons that innervate skeletal muscles.
- ✅ They are involved in fine, precise, and skilled voluntary movements, especially of the distal limbs (e.g., fingers and hands).
- ❌ They do not provide subconscious control; rather, they are part of the conscious (voluntary) motor system.
In contrast, subconscious control of skeletal muscle (like posture, balance, and coordination) is primarily handled by extrapyramidal tracts, such as:
- Vestibulospinal tract
- Reticulospinal tract
- Tectospinal tract
- Rubrospinal tract
These extrapyramidal pathways influence muscle tone and support automatic movements without conscious awareness.
Conclusion:
The lateral corticospinal tracts are responsible for conscious, voluntary control of skeletal muscles. The statement suggesting they control movements subconsciously is therefore false.