Brain Tidbit II Brainstem Medulla oblongata Pons Mesencephalon

Brain Tidbit II: Brainstem • Medulla oblongata • Pons • Mesencephalon (midbrain) Human Anatomy and Physiology I, Frolich, Brainstem

What is brainstem? • Interior inferior “core” of brain • Includes all parts of brain except: – – Cerebral hemispheres Cerebellum Diencephalon (remember “ 2 -oval skull”) • Think direct autonomic control Human Anatomy and Physiology I, Frolich, Brainstem Cerebral hemispheres Cerebellum “ 2 -oval skull” (brainstem deep and inferior)

Medulla oblongata (relay from the spinal cord) What is it? What it does? • Extension of spinal cord into cranial cavity • All motor and sensory information to and from peripheral nerves via spinal cord passes through • Central canal of spinal cord opens into fourth ventricle • Autonomic nuclei control visceral activity Human Anatomy and Physiology I, Frolich, Brainstem – Cardio-vascular: heart rate, strength of heart contractions, vasomotor (blood vessel opening) • Respiratory rhythmicity center • Nuclei for Cranial Nerves VIII-XII • Relay for sensory and motor information to other brain regions

Human Anatomy and Physiology I, Frolich, Brainstem

Pons (relay from “lower” to “higher” functions) • • Links higher to lower brain region Nuclei for Cranial Nerves V-VIII Nuclei that control respiration Part of “metencephalon” Human Anatomy and Physiology I, Frolich, Brainstem

Midbrain/Mesencephalon (integration of information for reflexive movements) • Superior to pons • Deep within brain • Superior and inferior colliculi—initiate reflexive responses to visual and auditory input • Substantia nigra and red nuclei (basal ganglia)—background skeletal muscle tone • Nuclei for Cranial Nerves III, IV Human Anatomy and Physiology I, Frolich, Brainstem

Human Anatomy and Physiology I, Frolich, Brainstem

Interactive overview of basic regions of brain from PBS [link] Human Anatomy and Physiology I, Frolich, Brainstem