Tectospinal tract

The tectospinal tract is a descending motor pathway that plays a vital role in reflexive postural adjustments in response to visual stimuli. Originating from nerve cells in the superior colliculus, part of the midbrain's tectum, the majority of its fibers cross the midline soon after their origin. These fibers descend through the brainstem, traveling close to the medial longitudinal fasciculus.

Within the spinal cord, tectospinal tract is located in the anterior white column near the anterior median fissure, primarily terminating in the anterior gray horns of the upper cervical spinal segments. At these termination points, the fibers synapse with lower motor neurons that control muscles of the neck and upper trunk. This arrangement enables the tectospinal tract to mediate reflexive head and neck movements (spinovisual reflexes) in response to visual stimuli. Examples include directing the head and neck toward a visually significant stimulus or initiating protective responses, such as turning away from potential threats or painful stimuli.

The tectospinal tract functions alongside other neural pathways, such as the tectobulbar tract, which controls eye movements. This collaboration aligns gaze direction and neck position with sources of visual stimuli, facilitating reflexive behaviors like tracking moving objects or reacting defensively to sudden visual signals. Additionally, its function is closely linked with the spinotectal tract, a sensory pathway that conveys signals, such as nociceptive or painful stimuli, to the superior colliculus. These sensory inputs trigger rapid motor responses mediated by the tectospinal tract, ensuring the effective orientation of the head and neck towards or away from environmental stimuli.

Through the integration of sensory and motor pathways, the tectospinal tract contributes to reflexive orientation and protective behaviors, allowing us to respond effectively to the surroundings.