1. Department of Human Anatomy
The State Medical and Pharmaceutical University “Nicolae Testemitanu”
Department of Human Anatomy
The functional Anatomy of the Nervous System
Lecturer Globa Lilian
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2. Coordination and Regulation of Body Systems
Nervous system.
Conducts nerve impulses maintaining homeostasis (electrochemical).
Endocrine system.
Serves as messaging system maintaining homeostasis (chemical).

3. Nervous & Endocrine Systems

4. Main Functions of the Nervous System
Connect the organism to the environments
Coordinate with all processes of the body
Adapt organism to the environments
Specific features of the human nervous system distinguish man from the animals (social life and speech)

5. Divisions of the NS CNS Central Nervous System Brain & spinal cord
PNS Peripheral Nervous System
Cranial nerves (12 pairs)
Spinal nerves (31 pairs)
Nervous plexus
Nerves

6. Divisions of the NS Somatic Nervous System
Visceral (Autonomic) Nervous System
Sympathetic
Parasympathetic

7. Somatic Nervous System
Somatic Sensitive
General somatic sense (touch, pain, pressure, vibration)
Proprioceptive sense (skin, body wall, limbs-muscles & joints)
Special somatic senses (hearing, equilibrium, vision, smell)
Somatic Motor
Skeletal muscle

8. Visceral (Autonomic) Nervous System
Visceral sense
General visceral: stretch, pain, temperature, chemical changes, irritation in viscera, nausea, hunger
Special visceral: taste
Visceral motor (ANS)
Smooth muscle
Cardiac muscle
Glands

12. Nervous tissue Neurons Supporting cells (neuroglia) unipolar neuron
pseudounipolar neuron
bipolar neuron
multipolar neuron
Supporting cells (neuroglia)

13. Neuron The functional and structural unit of the nervous system
Specialized to conduct information from one part of the body to another
Cell body (soma)
One or more specialized, slender processes (axons/dendrites)
An input region (dendrites/soma)
A conducting component (axon)
A secretory (output) region (axon terminal)

14. Dendrites Usually numerous Branched Sends signals to soma
The ends of the dendrites form receptors

15. Axons 1 per soma Initial segment from axon hillock
Transmits AP away from soma
No Nissl bodies (no protein synthesis)
Neurofilaments
Axonal transport
Axon collaterals
Terminal branches
Axon terminals

16. Neuron

17. 1. unipolar neuron 2. bipolar neuron
3. pseudounipolar neuron multipolar neuron
a. axon d. dendrite

18. Neuron classification by shape

19. CNS Neuroglia Outnumber neurons by about
10 to 1 (the guy on the right had an inordinate amount of them).
6 types of supporting cells
4 are found in the CNS:
Astrocytes
Star-shaped, abundant, and versatile
Guide the migration of developing neurons
Act as K+ and NT buffers
Involved in the formation of the blood brain barrier
Function in nutrient transfer

20. CNS Neuroglia Microglia Ependymal Cells
Specialized immune cells that act as the macrophages of the CNS
Ependymal Cells
Low columnar epithelial-esque cells that line the ventricles of the brain and the central canal of the spinal cord
Some are ciliated which facilitates the movement of cerebrospinal fluid

21. CNS Neuroglia 4. Oligodendrocytes
Produce the myelin sheath which provides the electrical insulation for certain neurons in the CNS

22. PNS Neuroglia 2 types of glia in the PNS Satellite cells Schwann cells
Surround clusters of neuronal cell bodies in the PNS
Unknown function
Schwann cells
Form myelin sheaths around the larger nerve fibers in the PNS.
Vital to neuronal regeneration

23. Myelin sheaths Wrapping of PM around axon
Phospholipid bilayers form insulation
Gaps between Schwann cells are nodes of Ranvier
Allow faster propagation of AP
Saltatory conduction

24. Nerve Bundle of axons in the PNS Endoneurium around each axon Loose CT
Perineurium – CT around a bundle of axons
Epineurium – CT around a nerve

25. Interneurons / association neurons
Located in CNS
>99% of all neurons
~ all multipolar
Integration of information

26. SYNAPSE Ÿ Presynaptic Portion: Synaptic Button Ÿ Synaptic Cleft
- synaptic vesicle
- mitochondria
- presynaptic membrane: tubulin
Ÿ Synaptic Cleft nm
Ÿ Postsynaptic Portion
- postsynaptic membrane: actin, fodrin, spectrin

27. SYNAPSE

28. SYNAPSE

30. Synapses
Presynaptic neuron
Postsynaptic neuron

31. Synapses
Axodendritic synapses
Axosomatic synapses
Axoaxonic synapses

32. Synapse structure Presynaptic element Synaptic cleft
Axon terminal
Synaptic vesicles
Neurotransmitters
Mitochondria
Synaptic cleft
Postsynaptic elements
NT receptors
May generate AP

34. Reflex arcs Reflex = rapid motor response to a stimulus Unlearned
Unpremeditated
Involuntary
Can involve all muscle types and/or glands

35. Knee-jerk stretch reflex
Monosynaptic reflex arc
Tap patellar tendon
Stretch quadriceps femoris
Stimulate stretch receptor
AP to motor neuron
Contract quadriceps femoris
Knee extends
12.18a

36. Withdrawal reflex
Polysynaptic
(12.18b)

37. 2 Main Paths Convergence and Divergence

40. Saltatory Conduction Appear the jump from node to node.
Speed of impulses is much faster on myelinated nerves then unmyelinated ones. Speed also increases with increase in diameter. Ex.) 120m/s skeletal muscle .5m/s skin

41. Neuron Communication

42. Developmental Aspects

43. Development

46. Structure of the Spinal Cord
FG14_01.JPG
Title: Gross Anatomy of the Spinal Cord
Notes: The spinal cord extends inferiorly from the base of thebrain along the vertebral canal. (a) Superficial anatomy and orientation of the adult spinal cord. (b) Inferior views of cross-sections through representative regions of the spinal cord, showing the a
Keywords: spinal cord, dorsal root ganglion, dorsal root, white matter, central canal, posterior median sulcus, spinal nerve, ventral root, anterior median fissure, cervical, thoracic, lumbar, sacral, coccygeal nerve, filum terminale

47. Meninges of the Spinal Cord
FG14_02.JPG
Title: The Spinal Cord and Spinal Meninges
Notes: (a) Anterior view of spinal cord showing meninges and spinal nerves. (b) MRI scan of inferior portion of spinal cord. (c) Posterior view of spinal cord; meningeal layers, superficial landmarks, distribution of gray and white matter. (d) Sectional view throu
Keywords: spinal cord, meninges, spinal nerves, anterior median fissure, pia mater, denticulate ligaments, arachnoid mater, dura mater, cervical nerve, rami communicantes, autonomic ganglion, ventral ramus

48. A Reflex Arc FG14_15.JPG Title: A Reflex Arc
Notes: This diagram illustrates the five steps involved in a neural reflex.
Keywords: reflex arc, stimulus, receptor, reflex arc, effector, CNS, motor neuron

49. Spinal Cord Reflex

50. Simple Nerve Path

53. The Spinal Cord
The spinal cord extends from the foramen magnum to the level of the 1st or 2nd lumbar vertebrae
It is enclosed within the vertebral column

54. The Spinal Cord
The spinal cord is a provides a two way conduction pathway to and from the brain
It is a major reflex center

55. The Spinal Cord
The spinal cord is protected by bone, cerebro- spinal fluid, and meninges
Dura mater, arachnoid, pia mater

56. The Spinal Cord
Between the bony vertebrae and the dural sheath is a large epidural space filled with a soft padding of fat and a network of veins
Cerebrospinal fluid fills the subarachnoid space

57. The Spinal Cord
Inferiorly, the dural and subarachnoid membranes extend to the level of S2 while the spinal cord ends at L1
Subarachnoid space beyond L1 is an ideal site for a spinal tap

58. The Spinal Cord
The spinal cord terminates in a tapering cone shaped structure called the conus medullaris

59. The Spinal Cord
A fiberous extension of the pia mater, the filum terminale extends inferiorly from the conus medullaris to attach to the posterior surface of the coccyx

60. The Spinal Cord
There are 31 pairs of spinal nerves that arise from the cord by paired roots and exit from the vertebral column via the intervertebral formina
Each segment of the spinal cord is defined by a pair of spinal nerves that lie just superior to their corresponding vertebra

61. The Spinal Cord
The spinal cord has obvious enlargements where the nerves serving the upper and lower limb arise
Cervical enlargement
Lumbar enlargement

62. Cross Section of Spinal Cord
The spinal cord has two grooves that mark its surface
Anterior median fissure / Posterior medial sulcus

63. Gray Matter and Spinal Roots
These grooves run the length of the cord and partially divide it into right and left halves
Gray matter inside, the white matter outside

64. Gray Matter and Spinal Roots
The gray matter consists of a mixture of neuron cell bodies, their unmyelinated processes, and neuroglia (support cells)

65. Gray Matter and Spinal Roots
The white matter is composed of myelinated and unmyelinated nerve fibers that represent ascending, descending and transverse pathways

66. Gray Matter and Spinal Roots
The gray matter consists of mirror-image lateral gray masses connected by a cross-bar of gray matter called the gray commissure that encloses the central canal

67. Gray Matter and Spinal Roots
The two posterior projections of gray matter are the posterior (dorsal) horns; the anterior pair are the anterior (ventral) horns with lateral horns in the lumbar and thoracic portions of the cord

68. Gray Matter and Spinal Roots
The anterior horns house nerve cell bodies of the somatic motor neurons
These send their axons out via ventral roots of the spinal cord to the skeletal muscles

69. Sectional Anatomy of the Spinal Cord
FG14_05A.JPG
Title: Sectional Organization of the Spinal Cord
Notes: (a) Transverse section of the spinal cord. (b)Left half shows important anatomical landmarks; right half indicates functional organization of gray matter. (c) Left half shows major columns of white matter; right half indicates anatomical organization of s
Keywords: spinal cord, posterior gray commissure, dura mater, arachnoid, central canal, anterior white commissure, pia mater, ventral root, dorsal root ganglion, anterior gray horn, dorsal root, posterior median sulcus, funiculus, lateral gray horn

70. FG14_01B.JPG
Title: Gross Anatomy of the Spinal Cord
Notes: The spinal cord extends inferiorly from the base of thebrain along the vertebral canal. (a) Superficial anatomy and orientation of the adult spinal cord. (b) Inferior views of cross-sections through representative regions of the spinal cord, showing the a
Keywords: spinal cord, dorsal root ganglion, dorsal root, white matter, central canal, posterior median sulcus, spinal nerve, ventral root, anterior median fissure, cervical, thoracic, lumbar, sacral, coccygeal nerve, filum terminale

71. Gray Matter and Spinal Roots
The amount of ventral gray matter present at a given level of the spinal cord reflects the amount of skeletal muscle innervated at that particular level
Thus, the anterior horns are the largest in the areas where the innervation for limbs is present
Cervical enlargement / arms
Lumbar enlargement / legs

77. Figure 10.07 Meninges and Ventricles of the Brain

86. Nerve Plexuses Plexus = “braid”
Nerves supplying the limbs form plexuses when they leave the spinal cord
Cervical
Brachial
Lumbosacral
Lumbar
Sacral

87. Nerve Plexuses FG14_09.JPG Title: Peripheral Nerves and Nerve Plexuses
Notes: An overview of selected peripheral nerves and the three major nerve plexuses: cervical, brachial and lumbosacral.
Keywords: peripheral nerves, plexuses, cervical plexus, brachial plexus, lumbar plexus, sacral plexus, lesser occipital, greater auricular, transverse cervical, supraclavicular, phrenic, axillary, musculocutaneous, thoracic, radial, ulnar, median, sciatic

88. Cervical Plexus Formed by spinal nerves C1 – C5
Nerves innervate the neck and shoulder region
Phrenic nerve to the diaphragm

89. Cervical Plexus FG14_10.JPG Title: The Cervical Plexus
Notes: The cervical plexus is illustrated in Figure
Keywords: cervical plexus, accessory (XI), hypoglossal (XII), lesser occipital, supraclavicular, phrenic, transverse cervical, greater auricular

90. Brachial Plexus Formed by spinal nerves C5 – C8 and T1
Nerves innervate the arm and shoulder
Radial nerve
Ulnar nerve
Median nerve (between radial & ulnar nerve)

91. Human Anatomy, 3rd edition
Brachial Plexus
FG14_11A.JPG
Title: The Brachial Plexus
Notes: (a) The trunks and cords of the brachial plexus.
Keywords: brachial plexus, superior trunk, middle trunk, inferior trunk, medial cord, lateral cord, posterior cord, musculocutaneous, median, radial, ulnar, axillary
Human Anatomy, 3rd edition
Prentice Hall, © 2001

92. Human Anatomy, 3rd edition
Brachial Plexus
FG14_11B.JPG
Title: The Brachial Plexus
Notes: (b) Anterior view, showing peripheral distribution of major nerves. (c) Posterior view.
Keywords: brachial plexus, superior trunk, middle, inferior, musculocutaneous nerve, median, ulnar, radial, digital, palmar interosseous, deep radial
Human Anatomy, 3rd edition
Prentice Hall, © 2001

93. Lumbar Plexus Formed by spinal nerves T12 and L1 – L4.
Innervates the medial and anterior portions of the thigh and lower abdominal regions
Lateral femoral cutaneous nerve

94. Human Anatomy, 3rd edition
Lumbar Plexus
FG14_13A.JPG
Title: The Lumbosacral Plexus, Part I
Notes: (a) Anterior view of the lumbar plexus; origins and major branches. (b) Anterior view of sacral plexus; origins and major branches. (c) Anterior view of the lumbosacral plexus and innervation of lower limb. (d) Posterior view of sacral plexus and associat
Keywords: lumbosacral plexus, lumbar plexus, sacral plexus, lumbosacral trunk, iliohypogastric nerve, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, obturator, tibial, peroneal, medial plantar, pudendal, gluteal, sciatic, saphenous
Human Anatomy, 3rd edition
Prentice Hall, © 2001

95. Human Anatomy, 3rd edition
Lumbosacral Plexus
FG14_13C.JPG
Title: The Lumbosacral Plexus, Part I
Notes: (a) Anterior view of the lumbar plexus; origins and major brances. (b) Anterior view of sacral plexus; origins and major branches. (c) Anterior view of the lumbrosacral plexus and innervation of lower limb. (d) Posterior view of sacral plexus and associat
Keywords: lumbosacral plexus, lumbar plexus, sacral plexus, lumbosacral trunk, iliohypogastric nerve, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, obturator, tibial, peroneal, medial plantar, pudendal, gluteal, sciatic, saphenous
Human Anatomy, 3rd edition
Prentice Hall, © 2001

96. Sacral Plexus Formed by spinal nerves L4 and L5, and S1 and S2
Innervates the posterior portion of the hip, thigh, and leg, and the genital region
Sciatic nerve

97. Sacral Plexus FG14_13B.JPG Title: The Lumbosacral Plexus, Part I
Notes: (a) Anterior view of the lumbar plexus; origins and major brances. (b) Anterior view of sacral plexus; origins and major branches. (c) Anterior view of the lumbrosacral plexus and innervation of lower limb. (d) Posterior view of sacral plexus and associat
Keywords: lumbosacral plexus, lumbar plexus, sacral plexus, lumbosacral trunk, iliohypogastric nerve, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, obturator, tibial, peroneal, medial plantar, pudendal, gluteal, sciatic, saphenous

98. Sacral Plexus FG14_13D.JPG Title: The Lumbosacral Plexus, Part I
Notes: (a) Anterior view of the lumbar plexus; origins and major brances. (b) Anterior view of sacral plexus; origins and major branches. (c) Anterior view of the lumbrosacral plexus and innervation of lower limb. (d) Posterior view of sacral plexus and associat
Keywords: lumbosacral plexus, lumbar plexus, sacral plexus, lumbosacral trunk, iliohypogastric nerve, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, obturator, tibial, peroneal, medial plantar, pudendal, gluteal, sciatic, saphenous
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