Guided Notes for the Central Nervous System

1. During embryonic development, the CNS frist appears as a simple tube, the neural tube, which extends down the dorsal median plane of the embryo’s body.

2. By the fourth week, brain formation begins.

3. The brain is often discussed in terms of its four major regions—cerebral hemispheres, diencephalon, brain stem, and cerebellum.

4. The paired cerebral hemispheres enclose and obscure most of the brain stem. The entire surface of the cerebral hemispheres exhibits elevated ridges of tissue called gyri, which are separated by shallow grooves called sulci. Less numerous are the deeper grooves called fissures, which separate large regions of the brain.

5. The cerebral hemispheres are separated by a single, deep fissure called the longitudinal fissure.

Lobes of the Cerebrum

Name Location Function Areas

Parietal Posterior to the central sulcus

Interprets impulses from body sensory receptors

Somatic sensory area

Occipital Rear of brain above the cerebellum

Interprets impulses from the eyes

Visual area

Temporal Bordering the lateral sulcus

Interprets impulses from the ears

Auditory area

Frontal Anterior to the central sulcus

Allows us to consciously move skeletal muscles

Primary motor area

7. Although most of the gray matter is in the cerebral cortex, there are several “islands” of gray matter, called basal nuclei, buried deep within the white matter of the cerebral hemispheres. The basal nuclei help regulate voluntary motor activities by modifying instructions sent to skeletal muscles by the primary motor cortex.

8. The 3 major structures of the diencephalon are the thalamus, hypothalamus, and the epithalamus. The thalamus is a relay station for sensory impulses passing upward to the sensory cortex.

8. The hypothalamus is an important autonomic nervous system center because it plays a role in the regulation of body temperature, water balance, and metabolism. Additionally, the hypothalamus regulates the pituitary gland and produces 2 hormones of its own.

9. The pituitary gland hangs from the anterior floor of the hypothalamus by a slender stalk.

10. The brain stem has 3 structures: the midbrain, pons, and medulla oblongata.

11. The pons is the rounded structure that protrudes just below the midbrain. It has important nuclei involved in the control of breathing.

12. The medulla oblongata contains centers that control heart rate, blood pressure, breathing, swallowing, and vomiting.

13. Like the cerebrum, the cerebellum has 2 hemispheres and a convoluted surface. The cerebellum provides the precise timing for skeletal muscle activity and controls our balance and equilibrium.

4 ways that the brain and spinal cord are protected by the body

Enclosing them within bone Membranes A watery cushion The blood/brain barrier