Which part of the brainstem serves as a bridge for motor tract to the cerebellum?
A) Pons
B) Midbrain
C) Reticular formation
D) Medulla oblongata

Question

Quizplus · Accepted Answer

The medulla oblongata is the most inferior section of the brainstem. All ascending sensory messages pass through the medulla oblongata on their way from the spinal cord to the thalamus. All descending motor messages also travel through the medulla oblongata on their way from the primary motor area in the frontal lobe of the cerebrum to the spinal cord and ultimately out to the skeletal muscles. The efferent, motor messages pass through two anterior raised areas on the medulla oblongata, called the pyramids. The motor messages cross sides at the pyramids, so messages coming from the right frontal lobe go to muscles on the left side of the body, and motor messages sent by the left frontal lobe go to muscles on the right side of the body. The medulla oblongata also contains centers to regulate heart rate, respiratory rate, and blood vessel diameter. The emetic center that controls vomiting is also located in the medulla oblongata. The pons appears as a large bulge on the anterior surface of the brainstem between the medulla oblongata and the midbrain. Like the medulla oblongata, the pons has ascending tracts of neurons carrying sensory messages to the thalamus and descending motor tracts from the cerebrum. The pons serves as a bridge for motor tracts to the cerebellum where they are fine-tuned before continuing on their way to the medulla oblongata and spinal cord. The midbrain appears as a hook at the superior end of the brainstem. It has four bulges, called colliculi on its posterior surface. The two superior colliculi are important for visual reflexes, as in tracking the movement of an object or focusing on something seen off to the side. The two inferior colliculi are important for auditory reflexes, such as turning your head towards a sound or jumping at the sound of a loud noise. Both colliculi direct the sensory messages on to the thalamus. The reticular formation is composed of groups of cell bodies (called nuclei in the CNS, ganglia in the PNS) scattered throughout the brainstem. The reticular formation is important for arousal, as it determines whether sensory messages will be consciously noticed by the cerebrum or not. It is also responsible for sleep/wake cycles.

Which Part of the Brainstem Serves as a Bridge for Motor