Namely, they are: olfactory nerve (CN I), optic nerve (CN II), oculomotor nerve (CN III), trochlear nerve (CN IV), trigeminal nerve (CN V), abducens nerve (VI), facial nerve (VII), vestibulocochlear nerve (VIII), glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI), and hypoglossal nerve (XII). Cranial nerves are numbered one to twelve according to their order of exit through the skull fissures. Central nervous systemĬranial nerves are peripheral nerves that emerge from the cranial nerve nuclei of the brainstem and spinal cord. Axons bundles within the PNS are called afferent and efferent peripheral nerves. Axons that extend from the CNS to connect with peripheral tissues belong to the PNS. These bundles within the CNS are called afferent and efferent neural pathways or tracts. Axon bundles pass impulses between the brain and spinal cord. Check out our quizzes and more for the nervous system anatomy practice!Īlthough divided structurally into central and peripheral parts, the nervous system divisions are actually interconnected with each other. But you're in luck, as we've got a learning strategy for you to master neuroanatomy in a lot shorter time than you though you'll need. They say that the nervous system is one of the hardest anatomy topic. Autonomic nervous system (ANS) - described as the involuntary system.Somatic nervous system (SNS) - informally described as the voluntary system.Peripheral nervous system (PNS) - gathers all neural tissue outside the CNSįunctionally, the PNS is further subdivided into two functional divisions.Central nervous system (CNS) - consists of the brain and spinal cord.The nervous system (NS) is structurally broken down into two divisions These organs unite according to their common function, forming the evolutionary perfection that is our nervous system. So nervous tissue, comprised of neurons and neuroglia, forms our nervous organs (e.g. This significantly increases the speed of neural impulse propagation. The neural impulses propagate through the Ranvier nodes only, skipping the myelin sheath. Myelin encloses an axon segmentally, leaving unmyelinated gaps between the segments called the nodes of Ranvier. Most axons are wrapped by a white insulating substance called the myelin sheath, produced by oligodendrocytes and Schwann cells. The PNS doesn’t have a glial equivalent to microglia as the phagocytic role is performed by macrophages.
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