1. Divisions of the Nervous System
Chapter 11

2. Meninges- membranes surrounding the brain & spinal cord
Dura Mater-fibrous - (outer)
1. brain-it lines the skull, but may split, forming a blood-filled dural sinus
2. spinal cord-has fat-filled epidural space between dura mater and bone
Arachnoid Mater-lines dura mater(middle)
Pia Mater-thin, covers surface of brain & spinal cord -vascular, nourishing (inner)
Subarachnoid space is between AM and PM (filled with cerebrospinal fluid)

6. Spinal Cord 31 segments ends between 1st & 2nd lumbar vertebrae
2 grooves: anterior median fissure and posterior median sulcus
On cross-section:
gray matter-posterior, anterior, and lateral horns, gray commissure, central canal (cerebrospinal fluid)
white matter- anterior, posterior, and lateral funiculi

10. Brain
Three Main Regions
Cerebrum - largest
Cerebellum
Brainstem

11. Cerebrum
2 cerebral hemispheres connected by band of white matter called the corpus callosum
shallow grooves on surface are sulci(sulcus)
deep grooves are fissures (longitudinal fissure, transverse fissure, lateral fissure)
folds/convolutions between sulci are gyri(gyrus)
Lobes: frontal, parietal, occipital, temporal
Cerebral Cortex:outer, thin layer of gray matter

12. Figure 11.15a

15. Functions of Cerebrum

16. Functional Regions of Cerebral Cortex
1. Motor Regions
a. Primary Motor Area-in precentral gyrus(directly in front of the central sulcus)- controls voluntary muscle movements(left hemisphere controls right side, vice versa)
b. Broca’s area-usually in left hemis. - muscle actions associated with speech
-regulates the patterns of breathing and vocalization needed for normal speech

17. 2. Sensory Regions
a. Primary Sensory Area-in postcentral gyrus (behind the central sulcus)
- receive somatic sensory info from receptors for touch, pressure, pain, vibration, taste, and temp.
b. Hearing – responsible for monitoring sound; recognizes sounds such as spoken words

18. c. Vision- Recognizes images and puts them together
Ex: when you see the symbols C, A, R this area of the brain recognizes that those are the letters that form the word car.

19. 3. Association Areas-all lobes
memory, reasoning, judgment, emotional expressions
a. General Interpretive Area (Wernicke area)-word recognition and expression (written interpretation)
- Plays an imp. Role in your personality

20. Figure 11.17

25. Hemisphere Dominance
Dominant Hemisphere: language, intellectual functions requiring verbal, analytical, and computational skills---usually the left hemisphere
Nondominant Hemisphere: nonverbal functions (musical, intuitive, and emotional expression)---usually the right hemisphere

26. Memory short-term: few seconds--as long as impulse travels
recent: minutes or days--lost if not consciously recalled
long-term: results from repeated recall or experience---promotes facilitation of neurons

27. Basal Ganglia/Basal Nuclei
Basal ganglia/nuclei are masses of gray matter deep within each cerebral hemisphere
They serve as a relay for motor impulses from cortex and as a source of inhibitory neurotransmitters such as dopamine (lack of dopamine causes Parkinson’s disease)
Inhibit muscular activities

29. Ventricles- interconnected cavities within brain filled with cerebrospinal fluid
Lateral ventricles (1st & 2nd)-within each cerebral hemisphere
Third ventricle-just under the corpus callosum
Fourth ventricle-within brainstem, in front of cerebellum
A channel called the cerebral aqueduct connects the 3rd and 4th ventricles.

32. Cerebrospinal Fluid
produced by choroid plexus (specialized capillaries lining the ventricles)
Know the flow of C-S fluid (see fig. 11.4)
drained through arachnoid granulations into the dural sinus
composition is clear, slightly viscous
functions: protection, maintains stable ionic concentration in CNS, pathway for wastes from CNS to blood

35. Diencephalon- surrounds the 3rd ventricle
Thalamus-sides of dienceph.-relay station for incoming sensory impulses from other parts of the nervous system--general awareness of pain, touch, temp., etc.
Hypothalamus-anterior floor of dienceph. - connects to pituitary; controls pituitary; body’s thermostat
Mammillary bodies (2)-olfaction and swallowing reflexes
Pineal gland-posterior projection

36. Limbic System-all structures in general region of diencephalon-Because they are connected to the cortex, they help in production of emotional feelings (fear, anger, pleasure, etc.)

38. Brainstem
Midbrain-surrounds cerebral aqueduct; contains all descending voluntary motor tracts; center for visual and auditory reflexes; postural reflexes
Pons-bulge on anterior surface of brainstem
Medulla Oblongata-connects to spinal cord--contains all ascending and descending tracts---contains many vital control centers: cardiac, vasomotor, respiratory, vomiting, coughing, etc.

40. Reticular Formation allows cortex to be in an aroused, conscious state
wakeup center

41. Cerebellum 2 hemispheres gray matter surrounds the white matter
white matter is called the arbor vitae (tree of life)
functions:
1. control of coordination of skeletal muscles
2. equilibrium (receives impulses from semicircular canals of inner ears)

42. Peripheral Nervous System
Each nerve is made of bundles of neuron fibers bound by C.T. An endoneurium surround each individual fiber within the nerve.

44. Types of Nerves Cranial Nerves 12 pairs
some sensory, some motor, most mixed
Name and number each (Table 11.9)
Old Otto Owens Told Tom About Finding Very Good Vacations Around Hawaii
Spinal Nerves
31 pairs, all mixed
cauda equina-group of descending spinal nerves below end of spinal cord but within vertebral column
all form plexuses except some thoracic nerves-->become intercostal nerves

45. Figure 11.25

47. Structure of a Spinal Nerve
Dorsal root (sensory root)--has dorsal root ganglion (contains cell bodies of sensory neurons)
Ventral root (motor root)
Branches: 1. meningeal branch-supplies meninges, vertebrae
2. posterior branch-muscle & skin of back
3. anterior branch-muscle & skin of front & sides of trunk--also limbs
4. visceral branch (thoracic region only) - supplies viscera

51. Somatic Division of PNS
voluntary
Motor impulses lead to skeletal muscles.
Motor pathway has 1 motor neuron.

52. Autonomic Division of PNS
involuntary
Motor impulses lead to smooth muscles and glands.
Motor pathway has 2 motor neurons: preganglionic fiber (myelinated) begins in CNS and ends at a PNS ganglion; postganglionic fiber (unmyelinated) begins at ganglion and ends at effector.

55. Comparison of the effects of sympathetic & parasympathetic divisions on each organ
Every organ is supplied by both sympathetic and parasympathetic impulses.
The effects are opposite.
See Table 11.10