1. Ch. 13 Central Nervous System

2. Introduction The CNS contains: Brain - encased by cranium
Spinal cord - encased by vertebrae

3. Coverings of the brain and spinal cord
Meninges membranes between bone and soft tissue
Dura mater – outermost, contains blood vessels
Forms periostium of skull bones
Forms partitions between lobes of brain and sinuses
provides resistance to pathogens
Prevents cerebral spinal fluid leaks
Arachnoid mater – middle. Thin, avascular
Pia mater – innermost, vascular, thin
Attached to brain and spinal cord surface.
Spaces
Epidural-between dura mater and covering of spinal cord.
Subdural – between dura mater/arachnoid mater. Contains serous fluid
Subarachnoid – between arachnoid and pia. Contains cerebrospinal fluid
Purpose – supportive cushion.
Headache – dilated vessels in meninges. Meningitis – inflammation of meninges caused by bacteria/virus. Produces fever, headache, and if untreated, death.

4. Structure of the Spinal cord
Description and location
Structure
31 Segments with a pair of spinal nerves in each segment
8 cervical
12 thoracic
5 lumbar
5 sacral
CX - in coccyx
Cervical enlargement
Lumbar enlargement
Plexus - clump
Grooves
Anterior media fissure
Posterior median sulcus
White matter – myelinated fibers
Gray mater - cell bodies and dendrites of interneurons. (butterfly shaped)
Cerebrospinal pressure is measured by needle inserted between lumbar vertebrae in sub arachnoid space. Sample is checked for abnormal constituents.

5. Function of the spinal cord
Functions
Transmit impulses
House spinal reflexes
Ascending (sensory)
descending tracts (motor)
Names of tracts – identify origin and termination of fibers in tract (ex. Spinothalamic tract)

6. The myteries of the human brain

7. The brain Introduction - largest part of the nervous system
100 billion multipolar neurons.
Divisions
Cerebrum – largest/higher mental functions
Diencephalon – process sensory input
Cerebellum-coordinates muscular activity
Brainstem-coordinates/regulates visceral activities

8. The cerebrum The largest part of the brain
Surface of the brain is marked by convolutions, sulci, fissures.
Lobes of the brain are named according to the bones they underlie.
2 hemispheres connected by Corpus callosum
Convolutions, sulci, fissures
Lobes
Frontal
Parietal
Temporal
Occipital
Cerebral cortex - thin layer of gray mater - 75% of cell bodies

9. Functions of the cerebrum
Higher brain functions
Interpretation of sensory input
Initiating voluntary muscular movement
Memory
Integrating information for reasoning
Consciousness
Language
Emotions

10. Functional regions of cerebral cortex
Primary motor area-frontal lobes, anterior wall
Broca’s area coordinates muscular activity for speech
Frontal eye field - controls eye and eye lid movement
Sensory areas - interpret sensory input, produce feelings/sensations
Association areas interpret sensory impulse, reasoning, judgment, emotions, story memory
Cross-over - right side controls left side of body, etc.
Interpretive areas-located where lobes come together - higher intellectual processes.
Damage
Occipital lob - sight and images
Temporal lobe - recent memories - inability to form long term memories.

11. Hemisphere dominance Both cerebral hemispheres receive/analyze
Most people exhibit dominance of left or right hemispheres.
Left hemisphere is dominant in 90%
Left hemisphere dominance usually results in being right handed, etc.
Non dominant hemisphere specialize in nonverbal function, emotion control/intuitive thinking

12. Ventricles and cerebrospinal fluid
Description - series of connective cavities containing cerebrospinal fluid. Continuous with the spinal cord
Choroid plexuses
Specialized capillaries that Secrete cerebrospinal fluid
Comes from lateral ventricles
Cerebrospinal fluid
Nutritive
Protective
Pressure - normally constant. Infection /tumor can increase pressure - causes damage

13. Diencephalon Location - above brain stem Contains:
thalamus -sorts and directs sensory information - filters non-essential information
Hypothalamus - maintains homeostasis/ linked to endocrine system
Optic tracts and chasmas - connect sense of sight
Infundibulum - attachment for pituitary
Pituitary gland - certain hormone production.
Pineal gland - puts you to sleep
Limbic system - controls emotional experience and expression
Guides behavior that increases chance of survival.

14. Consists of
Midbrain- conveys impulses to and from other parts of the brain
Reflex centers
Pons-between midbrain and medulla oblongata
Regulates rate and depth of breathing
Transmits impulses between brain and spinal cord
Medulla oblongata - transmits ascending and descending impulses
Controls visceral functions - cardiac center - heart rate, blood pressure control, respiratory center, cough and vomiting centers, sneezing
Reticular formation-wakes up the cerebral cortex
Decreased activity results in sleep, increased - wakefulness
Filters sensory impulses
If damaged, can’t wake from a coma.
Brainstem

15. Cerebellum Made of two hemispheres connected in the middle.
Cerebellar cortex - gray matter
Communicates with others parts of cns.
Integrates sensory information about position of body parts and coordinates skeletal muscle activity to maintain posture.

16. language
Ability to speak/write words and ability to understand spoken/written words. Speech center – areas in frontal, parietal, temporal lobes. Left cerebral hemisphere contains speech centers in 90% of population Aphasias - damage to speech centers - can’t speak.

17. Emotions Limbic system -known as the “emotional brain”
Medial surface of cerebrum and region called hippocampus
Connection to olfactory sense

18. Memory Cortex stores and retrieves short and long term memory
Repetition is the key to transferring information from short to long term memory
If you don’t use it you lose it.
Closely connected to limbic system
Forgetting is the atrophy of a neural connection that was created when learning took place.