4BBY1030 Cell Biology and Neuroscience - Organisation of the Nervous System PDF

Institute of Psychology, Psychiatry and Neuroscience October 2023 Dr Suba Poopalasundaram Neuroscience Education 4BBY1030 Cell Biology and Neuroscience Organisation of the nervous system Chapter 1 Organisation of the Nervous System Dr Clemens Kiecker Organisation of the nervous system 2 General orga...

Institute of Psychology, Psychiatry and Neuroscience October 2023 Dr Suba Poopalasundaram Neuroscience Education 4BBY1030 Cell Biology and Neuroscience Organisation of the nervous system Chapter 1 Organisation of the Nervous System Dr Clemens Kiecker Organisation of the nervous system 2 General organisation of the nervous system Dr Clemens Kiecker Organisation of the nervous system 3 The major subdivisions of the nervous system Cranial nerves Spinal nerves Brain Central Nervous System (CNS) = brain + spinal cord Peripheral Nervous System (PNS) = somatic + visceral Spinal cord Somatic nervous system: Motor fibres = general somatic efferents (GSEs) Sensory fibres = general somatic afferents (GSAs), special senses (vision, hearing, taste, smell) Visceral nervous system: sympathetic = ‘fight or flight’ parasympathetic = ‘rest and digest’ Motor fibres = general visceral efferents (GVEs) Sensory fibres = general visceral afferents (GVAs) [Drake et al. (2015) Gray’s Anatomy for Students. Elsevier.] Dr Clemens Kiecker Organisation of the nervous system 4 CNS or PNS? Cranial nerves Spinal nerves Brain Spinal cord A CNS neuron is a neuron that is entirely contained within the brain or spinal cord. If any part of a neuron (cell body, dendrites or axon) is projects outside of the CNS, then it is a PNS neuron. [Drake et al. (2015) Gray’s Anatomy for Students. Elsevier.] Dr Clemens Kiecker Organisation of the nervous system 5 The autonomic nervous system Dr Clemens Kiecker Organisation of the nervous system 6 White and grey matter White matter: mostly axons (forming fibres/tracts) Grey matter: cell bodies (cortical layers or clusters of neurons = nuclei) Dr Clemens Kiecker Organisation of the nervous system 7 Anatomical terminology Dr Clemens Kiecker Organisation of the nervous system 8 The surface of the cerebrum is folded Ridges = gyri (sg. gyrus) Grooves = sulci (sg. sulcus) Deep grooves = fissures Dr Clemens Kiecker Organisation of the nervous system 9 Major subdivisions of the brain Dr Clemens Kiecker Organisation of the nervous system 10 The cerebrum is divides into lobes Executive functions (thinking, planning, organising, problem solving, emotion, behaviour, personality, motor control) Sensory processing, arithmetics, spelling Vision No function is located just within one lobe No lobe is associated with just one function Memory, language Dr Clemens Kiecker Organisation of the nervous system 11 The spinal cord in the vertebral canal and the cauda equina 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal) The first spinal nerve emerges between the skull and vertebra C1 C8 emerges between vertebrae C7 and T1 The spinal cord is shorter than the vertebral column (usually ends between L1/2) à cauda equina (Lat. horse’s tail) Lumbar puncture at L3/4 Back pain [Drake et al. (2015) Gray’s Anatomy for Students. Elsevier.] Dr Clemens Kiecker Organisation of the nervous system 12 Spinal nerves are ‘mixed’ – they contain motor and sensory fibres Dr Clemens Kiecker Organisation of the nervous system 13 Spinal nerves Spinal cord is segmented. Spinal nerves enter and leave as a collection of nerve rootlets. Dr Clemens Kiecker Organisation of the nervous system 14 Chapter 2 The ventricular system Dr Clemens Kiecker Organisation of the nervous system 15 Ventricular system Four ventricles + spinal canal Filled with cerebrospinal fluid (CSF) Dr Clemens Kiecker Organisation of the nervous system 16 Ventricular system Dr Clemens Kiecker Organisation of the nervous system 17 Ventricles Cerebrospinal fluid (CSF) Made by choroid plexus epithelium (specialised ependymal cells – see Lecture 7) Functions: - Buoyancy - Protection - Removal of waste products - Growth and signalling factors Dr Clemens Kiecker Organisation of the nervous system 18 Hydrocephalus Approx. 500 ml of CSF per day Normally re-absorbed into the venous blood stream If this pathway is blocked à hydrocephalus Schoenwolf et al., Larsen’s Human Embryology Dr Clemens Kiecker Organisation of the nervous system 19 Chapter 3 The coverings of the CNS - meninges Dr Clemens Kiecker Organisation of the nervous system 20 Learning Outcomes The CNS has three layers of meninges: 1. The innermost pia mater 2. The intermediate arachnoid mater 3. The outermost dura mater CSF leaves the ventricular system of the brain through apertures (foramina) and is released into the space between layers 1 and 2 à the sub-arachnoid space Dr Clemens Kiecker Organisation of the nervous system Pia mater EM Section through cerebral cortex. P: Pia mater, N: Astrocyte nucleus. Arrow: basal lamina of CNS (glia limitans) Bar = 1 mm Protects the CNS (together with the other meninges) A fine, vascular membrane that also allows entry of blood vessels into the CNS Provides an impermeable layer for containing CSF (Arrow = glia limitans = basal lamina of the CNS) Dr Clemens Kiecker Organisation of the nervous system 22 Arachnoid mater Protects the CNS (together with the other meninges) A cobweb-like membrane that forms the upper limits of the sub-arachnoid space Is closely associated with the dura mater Dr Clemens Kiecker Organisation of the nervous system 23 Dura mater Protects the CNS (together with the other meninges) In the skull, composed of two layers which separate in places to form sinuses carrying venous blood Surrounding the brain, the dura mater is closely attached to the periosteum of the cranium; surrounding the spinal cord, it hangs loosely, only attached at the foramen magnum Dr Clemens Kiecker Organisation of the nervous system 24 CSF is recycled into venous blood via arachnoid granulations Dr Clemens Kiecker Organisation of the nervous system 25 Summary 1. The nervous system can be subdivided by functional or anatomical criteria. 2. Examples of anatomical divisions of the CNS would be: spinal cord, hindbrain, midbrain and forebrain. 3. The CNS is hollow; a central canal runs the length of the spinal cord and is continuous with the ventricular system of the brain. 4. The central canal and ventricles are filled with CSF which is produced by the choroid plexus and reabsorbed into the venous bloodstream via the arachnoid granulations. 5. The brain is covered by 3 meningeal layers. These are (from inside to outside) the pia mater, arachnoid mater and the dura mater. 6. In addition to the ventricular system, CSF is found throughout the subarachnoid space. Dr Clemens Kiecker Organisation of the nervous system 26 Thank you for your attention [email protected] © King’s College London. All rights reserved