Learning Objectives

1. Learning Objectives • Name the major regions of the brain and describe their functions. • Discuss the formation, circulation and functions of the CSF. • List the main components of the medulla oblongata, the pons, the cerebellum, the mesencephalon, the diencephalon, and the limbic system and specify their functions.

2. Learning Objectives • Identify the major anatomical subdivisions of the cerebrum. • Locate the motor, sensory and association areas of the cerebral cortex and discuss their functions. • Describe representative examples of cranial reflexes.

3. Major regions and landmarks • Six regions in the adult brain • Cerebrum • Diencephalon • Mesencephalon • Pons • Cerebellum • Medulla oblongata • Brain contains extensive areas of neural cortex • Layer of gray matter on the surface of the cerebellum and cerebrum

4. Figure 14.1 The Adult Brain Figure 14.1a, c

5. Figure 14.1 The Adult Brain Figure 14.1b

6. Figure 14.1 The Adult Brain Figure 14.1d

7. Figure 14.2 An Introduction to Brain Functions Figure 14.2

8. Embryology of the brain • Brain forms from three swellings at the tip of the developing neural tube • Prosencephalon • Forms the telencephalon (forebrain; ultimately forms the cerebrum in adult) and the diencephalon (division that includes the epithalamus, thalamus, and hypothalamus). • Mesencephalon- The midbrain; region between the diencephalon and pons. • Rhombencephalon • Forms the metencephalon (cerebellum and pons) and myelencephalon (medulla oblongata)

9. Ventricles of the brain • Central passageway of the brain enlarges to form ventricles, four fluid filled interior chambers. • Chambers form from the expansion of the neurocoel within the cerebral hemispheres, diencephalon, metencephalon, and medulla oblongata. • Contain cerebrospinal fluid (CSF) • CSF continually circulates from the ventricles and central canal into the subarachnoid space of the cranial meninges. • The CSF passes between the interior and exterior of the CNS through foramina in the roof of the fourth ventricle.

10. Figure 14.3 Ventricles of the Brain PLAY Animation: Brain Dissections Figure 14.3a, b

11. The cranial meninges • Continuous with the three layers of the spinal cord • Folds of dura mater help stabilize the position of the brain. The three largest dural folds are the: • Falx cerebri-Curving sheet of dura mater that extends between the two cerebral hemispheres; encloses the superior sagittal sinus. • One of two large venous sinuses that lie within the falx cerebri. • Tentorium cerebelli- Dual partition that separates the cerebral hemispheres from the cerebellum. • Falx cerebelli- Divides the two cerebral hemispheres along the midsagittal line inferior to the tentorium cerebelli.

12. Figure 14.4 The Relationship among the Brain, Cranium, and Meninges Figure 14.4a, b

13. Cerebrospinal fluid (CSF) • CSF cushions delicate neural structures • Supports the brain • Transports nutrients, chemical messengers, and waste products • Pathway of CSF • Produced at the Choroid plexus, a vascular complex in roof of 3rd and 4th ventricles. • Travels through the lateral and medial apertures to the subarachnoid space • Diffuses across the arachnoid granulations into the superior sagittal sinus

14. Figure 14.5 The Circulation of Cerebrospinal Fluid Figure 14.5a, b

15. Blood supply to the brain • Blood brain barrier isolates neural tissue from general circulation • Blood-brain Barrier: Isolation of the CNS from general circulation. • Blood-CSF Barrier: Isolation of CSF from the capillaries of the choroid plexus. • Incomplete barrier in areas: • Parts of the hypothalamus • Pituitary gland • Pineal gland • Choroid plexus