Figure 4.8 The human brain stem This composite structure extends from the top of the spinal cord into the center of the forebrain. The pons, pineal gland, and colliculi are ordinarily surrounded by the cerebral cortex.
The Brainstem: Medulla oblongata Most inferior portion, functions as a conduction pathway (descending motor neuron pathways decussate here) Reflex centers for: regulating heart rate blood vessel diameter coughing, sneezing breathing swallowing
The Brainstem: Pons Superior to Medulla oblongata. Contains more ascending and descending pathways. Relays information from cerebrum to cerebellum. Also includes sleep and respiratory centers.
The Brainstem: Midbrain Small section superior to the pons. Part of the auditory pathways and visual reflexes Also involved in regulating muscle tone/activity and coordination
The Brain: Reticular formation 2 types of nuclei: Cranial nerves III-XII and Reticular Formation nuclei which are scattered throughout brainstem Many pathways from RF project directly to cerebrum to modulate activity Habituation (repetitive stimuli) Reticular Activating System
The Diencephalon: Thalamus “Gateway to cerebral cortex” Most sensory stimuli project to the thalamus, which in turn projects to the cerebrum. Thalamus also influences moods and activities associated with strong emotion. (Two concepts: Sensory integration and Mood)
The Diencephalon: Hypothalamus Major control center of autonomic nervous system and endocrine system. Centers associated with: * Food/H2O intake * Thermoregulation * Cardiovascular regulation * Hormone secretion * Sleep/waking * Emotional behavior