Nervous System Anatomy PDF

 Nervous system A.Nerve cell "Neuron" Structure :  Cell Body (soma): The nucleus is usually central in position. wy  Processes:...

 Nervous system A.Nerve cell "Neuron" Structure :  Cell Body (soma): The nucleus is usually central in position. wy  Processes: Dendrites Axon  Short  Long  Branching  Single da  Transmit impulses to soma  Transmit impulses from soma Types :  According to size: large (golgi type І) & small (golgi type П) en  According to function: motor , sensory & mixed  According to number of processes: Unipolar Bipolar Multipolar  True: amacrine cells of retina  olfactory nerve cells anterior horn cells of  Pseudo: dorsal root ganglion H  cochlear & vestibular spinal cord B. Neuro-glial cell R. In central nervous system In peripheral nervous system  Astrocytes: Supporting cells  Satellite: Supporting cells  Oligodenderocyte: form myelin sheath  Schwan: form myelin sheath  Microglia: phagocytic cells D  Ependymal: produces CSF Anatomist “Nervous system” N.B: Nucleus: collection of nerve cells inside the CNS. N.B: Ganglion: collection of nerve cells outside the CNS. N.B: Synapse: wy Definition Contact between nerve cells and the effector organ such as other neuron or muscle or gland  Pre-synaptic element: the end of axon containing vesicle Structure  Synaptic cleft  Post- synaptic element o Axo-dendertic da o Axo-somatic Types o Axo-axonic o Neuro-muscular en H R. D Anatomist “Nervous system”  Classification of nervous system Central nervous system Brain wy Anatomically: it is formed of  Cerebrum: formed of:  2 cerebral hemispheres  Diencephalon formed of da thalamus & hypothalamus  Cerebellum: for equilibrium “balance”  Brain stem: formed of midbrain, pons & medulla en Embryologically: it is formed of  Forebrain: resemble the cerebrum  Midbrain  Hindbrain: formed of pons , medulla & cerebellum Spinal cord  Length: 45 cm in male & 42 in female H  Begins: continuation of the medulla oblongata. R.  Ends: In newborn end at the level of (L3) while in adult end at the level of (L1)  Segments: 31 segments “8 cervical – 12 thoracic -5 lumbar – 5 sacral- 1coccygeal” D Anatomist “Nervous system” N.B: CNS is surrounded by Meninges “from inside outside”: A. Pia B. Arachnoid C. Dura. wy N.B: CSF "cerebro-spinal fluid" is found in brain ventricles :  Lateral ventricles: found in cerebral hemispheres  3rd ventricle: found in Diencephalon  4thventricle:found in hindbrain da en H R. D Anatomist “Nervous system”  Peripheral nervous system Cranial nerves Number Name Origin Function wy 1. Olfactory Nose Smell 2. Optic Retina Vision 3. Occulomotor da Midbrain Eye movement 4. Trochlear 5. Trigeminal Face sensation 6. Abducent Eye movement en Pons 7. Facial Face muscles 8. Vestibulococclear Hearing & balance 9. 10. 11. Glossopharyngeal Vagus Accessory Medulla H Tongue & pharynx Viscera Larynx R. 12. Hypoglossal Tongue muscles All cranial nerves arise from brainstem except olfactory nerve “from nose” & optic “from eye” D Anatomist “Nervous system”  Spinal nerves Distribution: 31 pairs “8 cervical, 12 thoracic, 5 lumbar, 5 sacral & 1 coccygeal” Formation: Each spinal nerve arises by 2 roots: wy  Dorsal Sensory root: formed of central processes of dorsal root ganglion  Ventral Motor root: formed of da o Axons of anterior horn cells “AHCs”: to skeletal muscles. o Axons of lateral horn cells” LHCs”: to smooth muscles Then the 2 roots unite forming the trunk of spinal nerve. en Branches: The trunk is divided into: Posterior Ramus Anterior Ramus      Small Runs backwardH Does not share in plexuses formation    Large Runs forward Share in formation of plexuses R. Not attached to sympathetic chain Attached to sympathetic chain D Anatomist “Nervous system”  Autonomic nervous system Sympathetic Parasympathetic Cranio-sacral thoraco-lumbar Pre-ganglionic fibers from LHCs of spinal cord segments (T1→L2)  Cranial part: from cranial nerves (10,9,7,&3)  Sacral part: from S2,3,4 segments wy Post-ganglionic fibers from sympathetic chain (lateral to vertebral column) from parasympathetic ganglia (near the organs)  Dilate the pupil & Contract the sphincters  Constrict the pupil & Relax of the sphincters Function  ↑ heart rate & respiratory rate  ↓ heart rate & respiratory rate  ↓ intestinal movement  ↑ intestinal movement da en H R. D Anatomist “Nervous system”