BRAINSTEM

BRAINSTEM

1. FROM SUPERIOR TO INFERIOR, THE BRAINSTEM REGIONS ARE MIDBRAIN, PONS AND MEDULLA OBLONGATA

   • COLLECTIVELY THEY ACCOUNT FOR ONLY 2.5% OF TOTAL BRAIN MASS
   • MIDBRAIN
     • Located between the diencephalon and pons, we find four bumps representing two paired structures: the superior and inferior colliculi.
       • The superior colliculi are involved in eye movement and visual processing, while the inferior colliculi are involved in auditory processing.
       • The midbrain also contain the major dopamine producing nuclei of the brain: the ventral tegmental area and substantial nigra. Among other functions, the ventral tegmental area is involved in motivation and reward, while the substantial nigra plays an important role in movement.
   • PONS
     • Is the bulging brainstem reIgn wedged between the midbrain and medulla oblongata. Dorsally, the fourth ventricles separates it from the cerebellum. Pons is a large, rounded structure resembling a rounded bridge that connects the medulla and the midbrain.
       • Pons is home to a number of nuclei for cranial nerves and contains nuclei that deal with sensations from the head and face, motor movements of the eyes, face and mouth, hearing, equilibrium and automatic functions like tear and saliva production.
   • MEDULLA OBLONGATA
     • Is the most inferior part of the brainstem. It blends imperceptibly into the spinal cord at the level of the foramen magnum of the skull. The medulla is the point where the brainstem connects to the spinal cord. Medulla is essential for survival as it contains nuclei that ensure vital systems like de cardiovascular and respiratory systems are working properly.
       • Medulla also contains nuclei that are responsible for a number of reflexive actions, including vomiting, swallowing, coughing and sneezing. Several cranial nerves also exit the brainstem at the level of the medulla.

2. PRODUCE THE RIGIDLY PROGRAMMED, AUTOMATIC BEHAVIORS NECESSARY FOR SURVIVAL.

3. PROVIDES A PATHWAY FOR FIBERS TRACTS RUNNING BETWEEN HIGHER AND LOWER NEURAL CENTERS.