Drilling or scraping into the skull and removing a piece of the bone. The dura mater is then exposed without damaging underlying blood vessels and the brain. Used to treat brain injuries and healing through supernatural means. Evidence shows that trephination began around 10,000 years ago. Numerous trephined skulls have been found in Peru and Bolivia ancient burial sites. The Edwin Smith Papyrus is the world’s oldest known surgical document. In 1862, Smith bought the ancient manuscript but, it was not until 1930 that James H. Breasted translated and established its importance.The text consists of 48 cases dealing with wounds and trauma Of the 48 cases described 27 concern head trauma, 6 deal with spine, and 11 are skull fractures.Structure: Have a single process that’s attached to the cell body. This single process has dendrites on one end and an axon is the rest of the process.Function: The dendrites are located in the periphery and only the most distal portions of the peripheral process acts as receptive endings. The sensory information travels on the dendrite toward the soma. The axon stretches into the CNS at the spinal cord.Examples include most sensory neurons of the peripheral nervous system are unipolar neurons.Structure: A single dendrite extending from one side of the cell body and a single axon extending to the other side. Both processes can have many smaller branches.Function: They are always sensory and carry information about vision, equilibrium, hearing, and olfaction. Bipolar neurons are usually found in the retina of the eye, roof of the nasal cavity, and inner ear. Structure: Multipolar neurons constitute the majority of neurons in the brain. They have one axon and multiple dendrites.Function: One process serves as the axon, which conducts action potentials between cells. The remaining processes are dendrites. Together, the cell body and dendrites form the receptive zone of multipolar neurons.Examples include spinal motor neurons, pyramidal neurons, Purkinje cells.There are two types of dendritic trees in the cerebral cortex.Pyramidal cells =pyramid shaped(a) Stellate cells =star shaped (b)Cells that dendrites have spines are called spiny (c) and those that don’t are called aspinous. Pyramidal cells are spiny. On the other hand, stellate cells can be spiny or aspinous.
September 20, 2019 0 Comments