Introduction to CNS

1
Introduction to CNS
2

• The nervous system consists of
• CNS made up of brain and spinal cord
• PNS consisting of peripheral nerves and ganglia

3
(No Transcript)
4
(No Transcript)
5
Brain Description

• Brain weighs 3 to 3.5 pounds
• Major portions of the brain--brainstem, cerebrum,
  and cerebellum
• cerebrum is 83 of brain volume cerebellum
  contains 50 of the neurons

6

• Longitudinal fissure separates 2 cerebral
  hemispheres.
• Central sulcus separates frontal and
  parietal lobe.

7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
Cranial Meninges
11
Meninges of Vertebra Spinal Cord
12

• The massive cerebral hemispheres hide the other
  parts of the brain from view,

13

• Diencephalon The largest part of the
  diencephalon is the thalamus in fact, this is a
  paired structure.

14

• Basal ganglia These large neuronal areas are
  found within the brain its three parts are shown
• the caudate nucleus (head and tail), the
  putamen, and the globus pallidus.

15
(No Transcript)
16
Brain Ventricles
17
Ventricles and Cerebrospinal Fluid

• Internal chambers within the CNS
• lateral ventricles found inside cerebral
  hemispheres
• third ventricle is single vertical
• cerebral aqueduct runs through midbrain
• fourth ventricle is small chamber between pons
  cerebellum
• central canal runs down through spinal cord
• Lined with ependymal cells and containing choroid
  plexus of capillaries that produce CSF

18
Cerebrospinal Fluid

• Clear liquid fills ventricles and canals bathes
  its external surface (in subarachnoid space)
• Brain produces absorbs about 500 ml/day
• filtration of blood through choroid plexus
• Functions
• buoyancy -- floats brain so it neutrally buoyant
• protection -- cushions from hitting inside of
  skull
• chemical stability -- rinses away wastes

19
Flow of Cerebrospinal Fluid
20
Midbrain

• Mesencephalon
• Central aqueduct
• CN III and IV
• eye movement

21
Medulla Oblongata

• Ascending descending nerve tracts
• Nuclei of sensory motor cranial nerves (IX, X,
  XI, and XII)
• Cardiac center adjusts rate force of heart beat
• Vasomotor center adjusts blood vessel diameter
• Respiratory centers control rate depth of
  breathing
• Reflex centers for coughing, sneezing, gagging,
  swallowing, vomiting, salivation, sweating,
  movements of tongue head

22
(No Transcript)
23
(No Transcript)
24
Medulla and Pons
Olive
25
Pons

• Bulge in the brainstem, rostral to the medulla
• Ascending sensory tracts
• Descending motor tracts
• Pathways in out of cerebellum
• Nuclei concerned with sleep, hearing, balance,
  taste, eye movements, facial expression, facial
  sensation, respiration, swallowing, bladder
  control posture
• cranial nerves V, VI, VII, and VIII

26
Cerebellum

• Connected to brainstem by cerebellar peduncles
• White matter (arbor vitae) visible in sagittal
  section
• Sits atop the 4th ventricle

27
(No Transcript)
28
(No Transcript)
29
The Peripheral Nervous System

• Nervous structures outside the brain and spinal
  cord
• Nerves allow the CNS to receive information and
  take action

30
Functional Organization of the PNS
Figure 14.1
31
Basic Structural Components of the PNS

• Sensory receptors pick up stimuli from inside
  or outside the body
• Motor endings axon terminals of motor neurons
• Innervate effectors (muscle fibers and glands)
• Nerves and ganglia
• Nerves bundles of peripheral axons
• Ganglia clusters of peripheral neuronal cell
  bodies

32

• On Old Olympic Towering Top  A Famous Vocal
  German  Viewed Some Hops

33
Structural Organization of PNS in Region of a
Spinal Nerve
Figure 14.2