Nervous System Lec

• Nervous System is a group of tissues composed of highly specialized cells possessing the characteristics of excitability and conductivity
• SOMATIC EFFERENT is innervating somatic structures like skeletal muscles and skin.
• VISCERAL EFFERENT is innervating visceral or involuntary structures like smooth muscles, cardiac muscles and glands. This is the autonomic nervous system
• Neurons is the active conducting elements
• Neuroglia is the supporting elements including astrocyte, oligodendrocyte, microglia, ependymal cells
• NEURON is basic unit of the nervous system whichconducts electrical impulses from one part of the body to another
• ▪A. DENDRITES – transmit impulses toward the cell body▪▪B. AXONS – conducting impulses away from the cell body.
• SYNAPSE is point of connection between neurons.
• Main neurotransmitters:1.epinephrine (adrenalin)2. norepinephrine (nor adrenaline)3. acetylcholine
• . MYELIN SHEATH – insulating material covering axons in central and peripheral nervous system
• . MYELIN SHEATH is the electrical impulse jumps from node to node in myelin sheath instead of traveling continuously along the nerve fiber
• • Central nervous system includes the brain and spinal cord.

  -It is divided grossly into gray and white matter:
• A Gray matter

  • so called because of its appearance and preponderance of nerve cell bodies and true dendrites.

  B. White matter

  • composed chiefly of myelinated nerve fibers
• Brain is part of the central nervous system contained within the skull. most complex and largest mass of nervous tissue in the body and contains literally billions of nerve cells.

  • The average weight of the human brain in the adult is approximately 1380gms in the male and 1250 grams in the females.
• Forebrain (Prosencephalon)

  Telencephalon (cerebrum)

  b. Diencephalon ( thalamus, hypothalamus, epithalamus, subthalamus)

  2. Midbrain (Mesencephalon)

  Corpora quadrigemina (tectum) - 2 superior colliculi

          2 inferior colliculi

  b. Cerebral peduncles

  c. Cerebral Aqueduct of Sylvius (iter)

  3. Hindbrain (Rhombencephalon)

  1. metencephalon (cerebellum, pons)

  b. myelencephalon (medulla oblongata)
• CEREBRUM is  7/8 of weight of brain
•  CEREBRUM is discriminatory identification
•  CEREBRUM is for  use of  language, emotional behavior, initiation of movement
• Fissures of Cerebrum

  1. Longitudinal fissure
  2. Lateral Sylvian Fissure
  3. Central Sulcus
  4. Transverse Fissure
  5. Parieto-occipital Fissure
  6. Calcarine Fissure
• Transverse fissure is between the cerebellum and the cerebrum
• Parieto - occipital fissure is between the occipital and parietal lobes.
• Calcarine fissure found in the occipital lobe ; visual center
•  Frontal Lobe includes all the cortex lying  anterior  to the central sulcus  of Rolando and  above the  lateral sulcus Sylvius
• Frontal Lobe is  center for motor functions and personality
• Parietal Lobe is  lies posterior to central sulcus of Rolando and  above lateral Sylvian fissure.
• Parietal Lobe is center for sensory functions
• Temporal Lobe lies beneath the lateral  sulcus of  Sylvian
• Temporal Lobe is center for hearing and olfaction
• Occipital Lobe  occupies the posterior extremity of the cerebral hemisphere behind parieto-occipital fissure
• Occipital Lobe is visual center
• Insula ( Island of Reil) exposed when the lips of lateral Sylvian  fissure are separated
• Primary Motor Area or Pre-central gyrus controls voluntary movements in the opposite side of body; Brodmann's area 4
• Pre-motor Area is in front of the motor area
• Pre-motor Area exerts a controlling influence over the  motor area, ensuring an orderly series  of movements
• Pre-frontal Area concerned with behavior, character and emotional state of the individual.
• Pre-frontal Area concerned with foresight, good  judgment, abstract thinking.
• Primary sensory/Somesthetic Area or Post-central gyrus lies behind the central sulcus of  Rolando in parietal lobe
• Primary sensory/Somesthetic Area or Post-central gyrus is  sensations of pain, temperature,  pressure and touch, position and  movement sensation
• Primary sensory/Somesthetic Area or Post-central gyrus: Brodmann's area 3,1,2
• Motor speech area lies in inferior frontal gyrus of   dominant hemisphere; Broca's area (Brodmann's area 45, 44)