1. Essentials of Human Anatomy Nervous System II

2. Brain
An adult brain weighs between 1.35 and 1.4 kilograms (kg) (around 3 pounds) and has a volume of about 1200 cubic centimeters (cc).
Brain size is not directly correlated with intelligence
It is not the physical size of the brain that determines intelligence—it is the number of active synapses.

3. Functions of the Brain interprets sensations determines perception
stores memory
reasoning
makes decisions
coordinates muscular movements
regulates visceral activities
determines personality 3 3

4. The Brain’s 4 Major Regions
Prosencephalon (forebrain)
Telencephalon: cerebrum
Diencephalon: epithalamus, thalamus,hypothalamus
Mesencephalon (midbrain)
Mesencephalon: cerebral peduncles, colliculi
Rhombencephalon (hindbrain)
Metencephalon: pons, cerebellum
Myelencephalon: medulla oblongata

5. The Brain’s 4 Major Regions
The cerebrum is divided into two halves, called the left and right cerebral hemispheres.
Each hemisphere is subdivided into four functional areas called lobes.
Outer surface of an adult brain exhibits folds called gyri (gyrus) and shallow depressions between those folds called sulci (sulcus).
The brain is associated with 12 pairs of cranial nerves.

8. Lobes of Cerebral Hemispheres
Frontal
Parietal
Temporal
Occipital
Insula 8 8

9. Functional Regions of Cerebral Cortex
Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; contains 75% of all neurons in nervous system 9 9

12. Diencephalon Between cerebral hemispheres and above the brainstem
Surrounds third ventricle 12 12

13. Diencephalon Thalamus
gateway for sensory impulses heading to cerebral cortex
receives all sensory impulses (except smell)
channels impulses to appropriate part of cerebral cortex for interpretation
Hypothalamus
maintains homeostasis by regulating visceral activities
links nervous and endocrine systems 13 13

14. Diencephalon Limbic System Consists of portions of frontal lobe
portions of temporal lobe
hypothalamus
thalamus
basal nuclei
other deep nuclei
Functions
controls emotions
produces feelings
interprets sensory impulses 14 14

15. Brain Stem
Three Parts
Midbrain
Pons
Medulla Oblongata 15 15

16. Midbrain between diencephalon and pons
contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain 16

17. Pons rounded bulge on underside of brainstem
between medulla oblongata and midbrain
helps regulate rate and depth of breathing
relays nerve impulses to and from medulla oblongata and cerebellum 17 17

18. Medulla Oblongata enlarged continuation of spinal cord
conducts ascending and descending impulses between brain and spinal cord
contains cardiac, vasomotor, and respiratory control centers
contains various nonvital reflex control centers (coughing, sneezing, swallowing, vomiting) 18

19. Cerebellum inferior to occipital lobes
posterior to pons and medulla oblongata
two hemispheres
vermis connects hemispheres
cerebellar cortex – gray matter
arbor vitae – white matter
cerebellar peduncles – nerve fiber tracts
dentate nucleus – largest nucleus in cerebellum
integrates sensory information concerning position of body parts
coordinates skeletal muscle activity
maintains posture 19 19

22. Cranial Nerves 22 22

23. Meninges membranes surrounding CNS protect CNS three layers
dura mater – outer, tough
arachnoid mater – thin, weblike
pia mater – inner, very thin
Meninges 23 23

24. Spinal Meninges Three membranes surround all of CNS 3) Pia mater
1) Dura mater - "tough mother", strong
2) Arachnoid meninx - spidery looking, carries blood vessels, etc.
Subarachnoid space
3) Pia mater - "delicate mother", adheres tightly to surface of spinal cord
3) Pia mater
2) Arachnoid
1) Dura mater

25. Ventricles interconnected cavities
within cerebral hemispheres and brain stem
continuous with central canal of spinal cord
filled with cerebrospinal fluid (CSF)
lateral ventricles
third ventricle
fourth ventricle
cerebral aqueduct 25 25

26. Cerebrospinal Fluid secreted by choroid plexus
circulates in ventricles, central canal of spinal cord, and subarachnoid space
completely surrounds brain and spinal cord
clear liquid
nutritive and protective
helps maintain stable ion concentrations in CNS 26 26

27. Lumbar Puncture (= Spinal Tap)
For clinical examination of CSF or administration of radiopaque dyes, drugs and sometimes anesthetics
However: mostly “epidurals” for anesthetics

28. THE END