Central Nervous System

Major Anatomic regions of Brain Cerebrum Diencephalon Brainstem Cerebellum

Cerebrum

Left and right cerebral hemispheres make up the cerebrum Cerebral cortex (outer layer) is made of non- myelinated gray matter. Internal tissue is white myelinated white matter with small interspersed regions of gray matter called basal nuclei.

Cerebrum Surface of brain is convoluted Gyrus – bump Sulcus – shallow groove Fissure – deep groove Sulci divide brain into 4 lobes Frontal Parietal Temporal Occipital

Cerebrum Longitudinal fissure divides brain into left and right halves Left brain controls right side of body Right side controls left side of body

Cerebrum – Frontal Lobe Frontal lobe is sectioned off from the brain by the central sulcus Anterior to central sulcus is primary motor cortex – sends nerve impulses to control movement This area has been mapped to show what body parts are controlled in each region of cortex (motor output) Left frontal area also includes Broca’s area which controls tongue and lip movements required for speech

Cerebrum - Parietal Posterior to frontal lobes Includes primary somatic sensory cortex which interprets incoming sensory impulses This has been mapped as well to show sensory input

Cerebrum - Occipital Posterior to parietal lobes Responsible for vision

Cerebrum - Temporal Inferior to frontal and parietal Involved in speech, hearing, vision, memory and emotion

Diencephalon Deep inside the brain Includes thalamus, hypothalamus and epithalamus Thalamus: relay station Hypothalamus: key part of autonomic nervous system, regulating heart rate, etc Epithalamus: includes pineal gland that regulates sleep-cycle hormones

Brain Stem Size of a thumb Includes midbrain, pons and medulla oblongata Midbrain: relay station Pons: helps regulate breathing Medulla oblongata: regulates heart rate, blood pressure and breathing

Cerebellum Below occipital lobe Coordinates body movements including balance

Protection of Brain Skull Meninges Blood-brain barrier

The Meninges = protective membranes located between bone and soft tissues of the nervous system Dura mater - outermost layer Arachnoid mater - no blood vessels, in between layer (resembles a spider web) Pia mater -inner membrane, contains nerves and blood vessels to nourish cells

Dura mater is being peeled away in this photo.

Blood Brain Barrier Capillaries in brain are different from capillaries in other parts of the body. Only certain substances are allowed to pass through to the brain

Spinal Cord Goes from brainstem to beginning of lumbar region of spine Major pathway Protected by same mechanisms as brain Exterior portion is myelinated white matter Central area is butterfly shaped gray matter containing neuron cell bodies and interneurons Tips of butterfly are called horns