Dr Joel G. Soria lecture on Nervous System

1. Chapter 8 :
Nervous System
Joel G. Soria, MD

2. Sensory input
Integration
Homeostasis
Mental activity
Control of muscles and glands
Functions of the
Nervous System

3. • Central nervous system (CNS)
• Brain and Spinal Cord
• Peripheral nervous system (PNS)
• Sensory divisions
• Motor divisions
• Somatic motor nervous system
• Autonomic nervous system (ANS)
Division of Nervous
System

6. NEURON
AXON
DENDRITES
MYELIN
SHEATH
NODES OF
RANVIER
N
U
CLEU
S
AXON
HILLOCK
CELL BODY

7. 1. Neurons
2. Microglia
Astrocytes
Ependymal cells
Microglia
Oligodendrocytes
Schwann cells
Cells of the
NERVOUS SYSTEM
3. Myelin sheaths
4. Organization of Nervous Tissue
A. Grey matter
B. White matter

8. Types of Neuron
MULTIPOLAR
BIPOLAR
UNIPOLAR
Many dendrites, single axon
Most motor and CNS neurons
single dendrites,
single axon
Special sense organs
Single process
Most sensory neurons

9. Types of MICROGLIA
ASTROCYTES
EPENDYMAL CELLS
MICROGLIAL CELLS

10. OLIGODENDROCYTE
SCHAWNN
CELLS

11. Schwann
Cells

12. Organization of
Nervous Tissue
Gray Matter
non-myeline sheath
Brain – Cortex; PNS - Ganglion
White Matter
Myelined sheath
CNS – conduction pathways,
nerve tracts

17. conduction in an
unmyelinated
sheath

18. conduction in a
myelinated sheath

20. REFLEX – involuntary reaction in response to a stimulus
applied to the periphery and transmitted to the CNS.
Allows the person to move quickly
REFLEC ARC – Neuronal pathway in which the reflex
occurs
Basic foundation unit the nervous system
REFLEXES

21. 5 Basic
components

22. Convergent and
divergent pathway

23. Convergent and
divergent pathway

25. SPINAL CORD
Extends from the foramen
magnum to the 2nd
lumbar vertebrae
Cauda equina

27. SPINAL CORD
STRETCH REFLEX
• Simplest form of reflex
• Muscle contracts in response to a
stretching force applied to them
• Knee-jerk reflex / patellar reflex
WITHDRAWAL
REFLEX
• Remove a limb or body part from
a painful stimulus
• Usually involves flexor muscle
groups

29. Spinal
Nerves
• Arise along the lateral side
of the vertebra
• Formed by the union of the
dorsal and ventral roots
• All spinal nerves are mixed
(both sensory and motor) in
function
• Most of the spinal nerves are
organized in groups
“PLEXUSES”
1. Cervical plexus
2. Brachial plexus
3. Lumbosacral plexus

30. Cervical
plexus
• Arises from spinal nerves
C1-C4
• Innervates several
muscles on the neck.
• Innervates the PHRENIC
NERVE

31. Brachial
plexus
• Arises from spinal nerves C5-T1
• Forms 5 major Nerve of the Upper
Extremities
• Axillary nerve – Shoulder muscles
• Radial nerve – All muscles of the
posterior arm and forearm
• Musculocutaneous Nerve–
Anterior muscles of the arm
• Ulnar nerve – 2 forearm muscles
and the intrinsic muscle of the hand
• Median nerve – Muscles of the
anterior forearm

32. Lumbosacral
Plexus
• Arises from spinal nerves L1-S4
• OBTURATOR NERVE – innervate
the muscles of the inner thigh and
skin
• FEMORAL NERVE –muscles of the
Anterior thigh and skin (+ skin of
medial side of the leg)
• TIBIAL NERVE – Posterior thigh
muscles, anterior and posterior leg
muscles, and most of intrinsic foot
muscles.
• COMMON FIBULAR NERVE –
innervate the muscles of the inner
thigh and skin
• SCIATIC NERVE – conbination of
common fibular and tibial nerve

33. B R A I N

35. Brainstem
Connects spinal cord to
the brain
Consist of:
Medulla oblongata
Pons
Midbrain
Functions vital functions:
Control of heart rate,
blood pressure and
breathing

36. Medulla
Oblongata
Most inferior part of the
brainstem
Contains ascending and
descending
Pyramids- descending tracts
Conscious control of skeletal
muscle
Functions as:
Regulation of heart rate, blood vessel diameter,
breathing, swallowing, vomiting, coughing, sneezing,
balance, and coordination.

37. Pons
Contains ascending and
descending tracts
Relay information
between cerebrum and
cerebellum.
Footbridge
Functions as:
Breathing, swallowing, balance, and control.
Chewing and salivation.

38. Midbrain
Smallest region of the brainstem
Colliculi – 4 mounds posterior to the
midbrain
2 inferior – major relay centers for
auditory nerve pathways
2 superior – Visual reflexes;
turning the head on a tap shoulder,
sudden noise, bright flash of light
Coordination of eye movements and in diameter of pupil and lens
shape.
Substancia nigra – basal nuclei
Regulation of general body movement

39. Reticular
formation
Scattered throughout the brainstem
Regulating cyclical motor functions such as respiration,
walking, and chewing.
RAS (Reticular Activating System) – Arousing and
maintaining consciousness and in regulating sleep-
wake cycle.

40. Diencephalon

41. Largest part of diencephalon
Influences mood and registers unlocalized, uncomfortable
perception of pain.
Thalamus

42. Small area located superior-posterior to the thalamus
Emotional and visceral response to odors
Epithalamus

43. Most inferior part of the
diencephalon
Maintaining homeostasis
Control of body
temperature, hunger, and
thirst
Hypothalamus
Sexual pleasure, feeling of good after a meal, rage, and fear.
Infundibulum – funnel-shaped stalk
Major role in controlling hormones from the pituitary gland

44. Ascending Tracts

49. Homunculus