1. Anatomy of the nervous system (NS)

2. NS is the system that controls all functions of the body, interprets information and have the essence of mind and soul. NS has the following functions:
Sensory input – monitoring stimuli occurring inside & outside the body
Integration – interpretation of sensory input
Motor output – response to stimuli by activating effector organs

3. NS can be divided to: I- Central nervous system (CNS) Brain
spinal cord
II- Peripheral nervous system (PNS)
cranial nerves
spinal nerves

4. Central Nervous System

5. A- Brain: Brain is Mass of nerve tissue Protected by membranes & skull
A- Brain: Brain is Mass of nerve tissue Protected by membranes & skull. It consist of the following structures:
1- Cerebrum Largest section of the brain, Highly developed, makes up about 80% of total brain weight, divided to right and left hemisphere, each hemisphere divided into 4 lobes these are frontal, parietal, temporal and occipital. The cerebrum is Responsible for: reasoning, thought, memory, speaking, sensation, sight, hearing, voluntary body movement.

6. The cerebral surface is highly folded called cortex
The cerebral surface is highly folded called cortex. These folds to increase the brains" surface area. each fold called gyrus and the groove between folds called sulcus. The cortex containing neuron cell bodies that color it with gray brown color so the cortex also called gray matter. Cortex= gray matter Beneath the cortex there are a long connecting nerve fibers called axons which have a white color so the layer called white matter.

8. 2- Cerebellum
Located below the cerebrum, Responsible for:
coordination of muscles, balance and posture of the body.

9. 3-Brain stem : An important link between spinal cord and higher brain levels, conduct motor and sensory impulses between them. Brain stem include the following structures: midbrain, pons, medulla oblongata
I-Midbrain
Responsible for: conducting impulses between brain parts and certain eye reflexes
II-Pons
linking the cerebellum with the brain stem, cerebrum and spinal cord
G. Medulla Oblongata
Lowest part of brain stem, Connects to the spinal cord it is the center that regulate cardiovascular and respiratory rhythm

10. Neurons :
Neurons are specific cell types have the ability to receive and transmit signals, each cell consist of cell body and processes. The processes include dendrites and axon. Neurons can be classified to:
Unipolar : dendrite and axon emerging from same process.
Bipolar: axon and single dendrite on opposite ends of the soma.
Multipolar: two or more dendrites, separate from the axon

11. C-Neuroglia:
are non-neuronal cells that provide support and protection for neurons in the central and peripheral nervous systems. In the central nervous system, glial cells include oligodendrocytes, astrocytes, ependymal cells and microglia. In the peripheral nervous system glial cells include Schwann cells and satellite cells.

12. D-Blood Brain Barrier It is a barrier that formed by:
1. tight junction by between endothelial cells of brain vessels and capillaries.
2. Basement membrane layer
3. Astrocytes foot process
It limits permeability for most molecules except O2, CO2, alcohol, steroids, H2O and protects brain from diurnal fluctuations in chemicals and metabolites
Brain receives 15% of blood pumped by heart and responsible for about half of body’s glucose consumption, glucose move by transporters from plasma to the brain interstitium.

14. 8-Ventricles of the brain: Four hallow spaces located in the middle of the brain, connected to each other and filled with fluid called cerebrospinal fluid

15. 9-Cerebrospinal Fluid (CSF)
Fluid that circulates continuously between brain and spinal cord. Serves as nutrients carrier and shock absorber to protect brain and spinal cord also helps to remove metabolic products & wastes.

16. E-Meninges:
Consists of 3 membranes covering the CNS, these are:
Dura mater : thick, tough outer layer
Arachnoid membrane: middle delicate web-like layer
Pia mater: inner most layer with blood vessels to nourish the nerves

17. Spinal cord

18. It is the second part of the CNS, occupy the upper 2/3rd of the vertebral canal from foramen magnum superiorly to the level of L1/L2 inferiorly. It is considerably shorter than vertebral column because it doesn't grow as rapidly as the vertebral column during development.
The spinal cord gives rise to 31 pairs of spinal nerves which exit the vertebral column through the intervertebral spaces. The spinal cord is not uniform in diameter throughout its length. The spinal cord tapered inferiorly to form cone-like region called conus medullaris, the spinal cord ended at level of L1/L2 but the spinal nerve continue throughout the vertebral canal, resemble a horse "s tail therefor called cauda equine.

19. Spinal cord organization andfunction:

20. Peripheral Nervous System(PNS)
PNS includes all nerves outside the brain and spinal cord. It consists of
cranial nerves
spinal nerves
Cranial Nerves
12 pairs & their branches

22. B. Spinal Nerves
31 pairs & their branches, carries messages to & from the spinal cord, there are both sensory and motor nerves.
31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal