Neuroanatomy: Spinal Tracts Overview

A major descending motor pathway that originates from cells in the cerebral cortex, particularly the primary motor cortex. It plays a crucial role in controlling voluntary, discrete, and skilled movements, primarily affecting the distal portions of the limbs.

Large, specialized neurons in the cerebral cortex that contribute to the corticospinal tract, producing the largest diameter axons within this tract. They are responsible for transmitting motor signals to the spinal cord.

A bundle of nerve fibers that carries signals from the cerebral cortex to the brainstem and spinal cord, facilitating voluntary movement.

A narrow, passageway in the brain that serves as a conduit for nerve fibers connecting various brain regions, including the corticospinal tract.

A prominent bulge on the ventral surface of the medulla oblongata containing fibers of the corticospinal tract. It marks the point where the majority of these fibers decussate (cross over) to the contralateral side.

The primary descending motor pathway located in the lateral white matter of the spinal cord, carrying signals to the contralateral limbs for voluntary movement.

The less prominent descending motor pathway found on the ventral (front) side of the spinal cord, controlling movement in the ipsilateral limbs.

The point in the medulla oblongata where a significant portion of the corticospinal tract fibers cross over to the opposite side of the body, allowing the left cerebral hemisphere to control movement on the right side of the body and vice versa.

The corticospinal tract is a major descending pathway that controls voluntary movement. It originates in the cerebral cortex and travels down the spinal cord, where it synapses with lower motor neurons in the ventral horn. The tract's distribution is not uniform across spinal cord levels, with a majority of fibers terminating in the cervical region, where they control movements of the upper limbs.

The rubrospinal tract is a descending pathway that plays a role in controlling limb flexor tone. It originates in the red nucleus of the midbrain and descends ipsilaterally down the spinal cord, where it synapses with lower motor neurons. The tract is thought to be excitatory to flexor motor neurons.

The tectospinal tract is a descending pathway that is involved in mediating reflexes in response to visual stimuli. It originates in the superior colliculus of the midbrain, and then decussates to the opposite side, before descending down the spinal cord where it terminates in the cervical region. The tract receives visual input and thus plays a role in coordinating movements in response to visual cues.

Vestibulospinal tracts are descending motor pathways involved in maintaining balance and controlling posture. They originate in the vestibular nuclei in the brainstem, which receive input from the vestibular system. They descend ipsilaterally down the spinal cord where they synapse with lower motor neurons.

The lateral vestibulospinal tract originates from the lateral vestibular nucleus. It is located in the ventral funiculus of the spinal cord and primarily influences lower motor neurons involved in controlling extensor muscles, contributing to posture control.

The medial vestibulospinal tract originates from the medial vestibular nucleus. It is located in the medial longitudinal fasciculus and descends to cervical levels. This tract is involved in coordinating eye movements and head movements.

The reticulospinal tracts are descending pathways that originate in the reticular formation in the pons and medulla. These tracts influence both ipsilateral and contralateral motor neurons, contributing to gait, posture and muscle tone.

The medial reticulospinal tract originates from the pontine reticular formation and it descends ipsilaterally. The lateral reticulospinal tract originates from the medullary reticular formation and it descends bilaterally. Both tracts are located in the ventral funiculus of the spinal cord.