anatomy of the central nervous system: part 1

1. Anatomy of the Central Nervous System:Part 1 Lecture 10

3. Peripheral Nervous System Somatic Nervous System - SNS Sensory & Motor Autonomic Nervous System - ANS Sympathetic Division Parasympathetic Division Cranial Nerves - 12 Pair Spinal Nerves - 31 Pair ~

4. Terminology Afferent - toward Sensory Efferent - away from Motor ~

5. Dorsal - toward the back Ventral - toward the stomach Anterior & Posterior Rostral & Caudal ~ Terminology

7. Brainstem & spinal cord

10. Terminology Medial - toward the midline Lateral - away from the midline Ipsilateral - same side Contralateral - opposite side Decussate - crossover ~

11. Coronal - frontal cross-section - salami - front view Sagittal - side view hot-dog bun Horizontal - top view ~ Planes

15. Development of the Nervous System

16. Embryological Origin Embryo has 3 layers endoderm ---> internal organs mesoderm ---> muscles & skeleton ectoderm ---> nervous system & skin Neural plate (~3 weeks) sheet of cells neural groove folds rostral to caudal ---> tube ~

17. Development of N.S. Neural tube CNS develops from walls as tube develops dorsal portion pinches off & forms... Neural crest develops into all neurons of PNS Mesoderm somites ---> vertebrae & muscles ~

18. Neural Tube Defects Neural tube fails to close Rostral failure anencephaly skull & brain partially or totally absent perinatal mortality Encephalocele parts of brain protrude outside skull mental disability depends on extent ~

19. Neural Tube Defects: Spina Bifida Cleft spine Caudal neural tube fails to close Incidence Spina bifida occulta 40% of Americans Spina Bifida Manifesta 1 in a 1000 births myelomeningocele: 96% meningocele: 4% ~

20. Neural Tube Defects: Spina Bifida Myelomeningocele protruding cyst as with meningocele spinal cord / nerves in protruding sac Effects paralysis, incontinence, learning disabilities 70-90% also hydrocephalus can cause severe brain damage Repaired surgically ~

21. Neural Tube Defects: Spina Bifida Meningocele fluid-filled meningeal cyst protrudes through unfused vertebral arches SC/nerves not in sac repaired surgically less severe disability than myelomeningocele ~

22. Neural Tube Defects: Prevention Possible genetic component reoccurrence in families ethnic/racial relationship Folic Acid (Folate) Deficiency 50-70% of cases preventable CDC guidelines not planning pregnancy: 400 mg/day planned pregnancy: 4000 mg/day under direction of health care provider ~

23. Stages of Cellular Activity 6 distinct stages 1. Neurogenesis mitosis nonneural cells neurons do not divide develop into neurons or glia glia produced throughout life ~

24. Stages of Cellular Activity 2. Cell migration to specific �brain� locations along radial glia later: along other neurons 3. Differentiation into specific neuron types by induction influenced by surrounding cells or cell-autonomous ~

25. Stages of Cellular Activity 4. Synaptogenesis formation of synapses growth of axons & dendrites growth cones 5. Neuronal cell death apoptosis: programmed cell death 20-80% of neurons in a region genetically programmed lack of neurotrophic factors ~

26. Stages of Cellular Activity 6. synaptic rearrangement elimination of synapse formation of new synapses dependent on neural activity ~

27. Differentiation Specialization of structures 3 primary vesicles rostral end of tube develops into brain Prosencephalon ---> forebrain Mesencephalon ---> midbrain Rhombencephalon ---> hindbrain ~

28. Prosencephalon Secondary vesicles form & separate optic ---> retinas retina & optic nerve part of brain not PNS telencephalic ---> telencephalon remainder ---> diencephalon ~

29. Other Primary Vesicles Mesencephalic ---> mesencephalon dorsal - tectum ventral - tegmentum tube - cerebral aqueduct Rhombencephalic rostral - metencephalon caudal - myelencephalon tube - 4th ventricle ~

30. Telencephalon Cortical areas Fiber systems Landmarks Fissures /Sulci Lobes Gyri ~

35. The Meninges Tough connective tissue Dura mater - tough outer layer Arachnoid membrane - soft middle layer Pia mater - soft inner layer, next to brain ~

36. Subarachnoid space Gap between arachnoid membrane and pia mater Filled with CSF Brain floats in CSF ~

37. Dura mater Arachnoid membrane Subarachnoid space CSF Pia mater The Meninges

38. Ventricular System Another circulatory system for the brain 4 interconnected ventricles chambers Cerebral Spinal Fluid (CSF) manufactured in choroid plexus Hydrocephalus - blockage of CSF flow ~

39. Ventricular System