1. Chapter 7 The Brain

2. Regions of the Brain Cerebral hemispheres Diencephalon Brain stem
Cerebellum
 A good indication of intelligence is brain weight in relation to body weight.  Sperm whale = largest brain 20 lbs.
  Mammal Body weight Brain weight How much of the animal is its brain?
Blue whale kg kg %
Lion kg g %
Rat g g %
Human kg kg %  

3. 1. Cerebral Hemispheres (Cerebrum)
Paired (left and right) superior
more than half of brain mass
Gyrus, sulcus, lobes & fissure, gray VS white
Figure 7.13a

4. Specialized Area of the Cerebrum
Figure 7.13c

5. Layers of the Cerebrum White matter
Fiber tracts inside the gray matter
Example: corpus callosum connects hemispheres
Basal nuclei – internal islands of gray matter
Figure 7.13a

6. 2. Diencephalon- Top of brain stem, in cerebrum
3 parts
Epithalamus - has pineal body (an endocrine gland) & choroid plexus – makes cerebrospinal fluid
Thalamus -Transfers impulses to correct part of the cortex localization and interpretation
Hypothalamus - autonomic NS system center (regulates temp, water balance, metabolism), limbic sys (emotions); connects to pituitary gland.

7. 3. Brain Stem - Attaches to the spinal cord
Midbrain Reflex centers for vision & hearing
Pons Mostly fiber tracts; nuclei involved in control of breathing
Medulla oblongata Merges w/spinal cord; control centers for:
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting M P MO

8. 4. Cerebellum 2 hemispheres with convoluted surfaces
involuntary coordination of body movements

9. Protection of the CNS Scalp and skin Skull & vertebrae Meninges
Cerebrospinal fluid
Blood brain barrier

10. 3. Meninges – connective tissue
Dura mater - Double-layered external covering; folds inward
-Periosteal – attached to surface of the skull
-Meningeal layer – outer covering of the brain
Arachnoid layer – Middle, web-like layer
Pia mater - Internal layer, Clings to the surface of the brain

11. 4. Cerebrospinal Fluid Similar to blood plasma
Formed by choroid plexus
watery cushion to protect the brain
Circulated in arachnoid space, ventricles, & central canal of the spinal cord

12. 5. Blood Brain Barrier Includes the least permeable capillaries
Excludes many potentially harmful substances
Useless against some substances
Fats and fat soluble molecules
Respiratory gases
Alcohol
Nicotine
Anesthesia

13. Cranial Nerves 12 pairs of nerves that mostly serve the head and neck
Numbered in order, front to back
Most are mixed nerves, but three are sensory only

14. Spinal Cord Anatomy Exterior white matter – conduction tracts
Internal gray matter - mostly cell bodies
- Dorsal (posterior) horns
- Anterior (ventral) horns
Central canal filled w/ cerebrospinal fluid

15. Spinal Cord Anatomy Meninges cover spinal cord
Nerves leave at each vertebrae
Dorsal root
Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system
Ventral root

16. Spinal Nerves pair of nerves at each vertebrae - 31 pairs
formed by combination of ventral & dorsal roots of the spinal cord
nerves are named for the region from which they arise

17. Anatomy of Spinal Nerves
Spinal nerves divide soon after leaving the spinal cord
Dorsal rami – serve the skin and muscles of the posterior trunk
Ventral rami – forms a complex of networks (plexus) for the anterior
Figure 7.22b
Slide 7.65
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

18. Examples of Nerve Distribution
Figure 7.23