Anatomy nerves

Wilson-Pauwels L, Akesson EJ, Stewart PA Sandoz Course, Cranial Nerves, Anatomy and Clinical Comments. Toronto BC Decker Inc., 1988. 

Fig. 4.2a-c. Nerve anatomy. In vitro a short-axis 12-5 MHz US image of the bovine sciatic nerve (arrows) with b correlative Tl-weighted MR imaging demonstrates a honeycombed nerve echotex-ture made up of small rounded hypoechoic areas (arrowhead), the fascicles, that are embedded in a hyperechoic background, the epineurium. Observe the definite grouping of fascicles within the sciatic nerve for the tibial (white arrows) and the peroneal (open arrows) nerves, c The in vitro model was prepared by incorporating the nerve (open arrow) within muscle tissue... 

Airway cross-sections have the nominal anatomy shown in Fig. 5.16. Airway surface liquid (AST), primarily composed of mucus gel and water, surrounds the airway lumen with a thickness thought to vary from 5 to 10 mm. AST lies on the apical surface of airway epithelial cells (mostly columnar ciliated epithelium). This layer of cells, roughly two to three cells thick in proximal airways and eventually thinning to a single cell thickness in distal airways, rests along a basement membrane on its basal surface. Connective tissue (collagen fibers, basement membranes, elastin, and water) lies between the basement membrane and airway smooth muscle. Edema occurs when the volume of water within the connective tissue increases considerably. Interspersed within the smooth muscle are respiratory supply vessels (capillaries, arteriovenous anastomoses), nerves, and lymphatic vessels. 

Jasper, HFI and Drooglewer-Fortuyn, J (1997) Experimental studies of the functional anatomy of petit mal epilepsy. Ass. Res. Nerv. Ment. Dis. Proc. 26 272-298. 

A related idea is that peripheral nerves are the source of the problem and then cause the associated vascular changes via release of 5-HT and other inflammatory mediators. The observation that the changes in the vasculature do not follow vascular anatomy has led to a new theory, that of spreading depression . Here, the primary abnormality is... 

FIGURE 29-1. Anatomy of the extrapyramidal system. The extrapyramidal motor system controls muscle movement through a system of pathways and nerve tracts that connect the cerebral cortex, basal ganglia, thalamus, cerebellum, reticular formation, and spinal neurons. Patients with Parkinson s disease have a loss of dopamine neurons in the substantia nigra in the brain stem that leads to depletion of dopamine in the corpus striatum. The corpus striatum is made up of the caudate nucleus and the lentiform nuclei that are made up of the putamen and the globus pallidus. 

V, proximal anastomosis within the temporal component, and distal interconnection between the latter and the cervical component VI, two anastomotic rami sent from the buccal division of the cervical to the zygomatic part of the temporal VII, transverse ramus, from the trunk of the nerve, contributing to the buccal ramus formed by anastomosis between the two major divisions VIII, richly plexiform communications, especially within the temporal portion of the nerve. From Barry J. Anson, Atlas of Human Anatomy, p. 37. 

First, you will learn about the human nervous system and how it works when it is healthy. This will include an introduction to the structure (anatomy) of the nervous system and the function (physiology) of the nervous system. Next, we ll describe the things that can go wrong. We ll look at how the system breaks down and malfunctions. Then we ll show you how these breakdowns can result in psychiatric illness. Finally, we ll introduce you to the medications used to treat psychiatric illness. You will learn where these medications work and our best guess of how they work. The presumed mechanism of action of many medications is just that, presumed. In contrast to antibiotics, in which we know quite a lot about the ways that they kill bacteria or stop them from reproducing and how these mechanisms ultimately effect a cure for an infectious disease, less is known about how psychotropic medicines work. Oh, we pretty well understand what psychotropic medicines do when they reach the nerve cell. For example, most of the antidepressants used today block the reuptake of serotonin at the nerve cell, but we re still not sure why blocking serotonin reuptake gradually improves mood in someone with depression. This will lead to a tour, if you will, of what happens to a medication from the time the pill is swallowed, until it exerts its therapeutic effect. 

Biochemistry is a dynamic, rapidly growing field, and the goal of this color atlas is to illustrate this fact visually. The precise boundaries between biochemistry and related fields, such as cell biology, anatomy, physiology, genetics, and pharmacology, are dif cult to define and, in many cases, arbitrary. This overlap is not coincidental. The object being studied is often the same—a nerve cell or a mitochondrion, for example—and only the point of view differs. 

The anatomy of autonomic synapses and junctions determines the localization of transmitter effects around nerve endings. Classic synapses such as the mammalian neuromuscular junction and most neuron-neuron synapses are relatively "tight" in that the nerve terminates in small boutons very close to the tissue innervated, so that the diffusion path from nerve terminal to postsynaptic receptors is very short. The effects are thus relatively rapid and localized. In contrast, junctions between autonomic neuron terminals and effector cells (smooth muscle, cardiac muscle, glands) differ from classic synapses in that transmitter is released from a chain of varicosities in the postganglionic nerve fiber in the region of the smooth muscle cells rather than boutons, and autonomic junctional clefts are wider than somatic synaptic clefts. Effects are thus slower in onset and often involve many effector cells. 

Tire anatomy of the brain is quite complex, and only a few terms will be defined here. Tire cerebrum, which is made up of two hemispheres, accounts for the largest part of the brain. Tire deeply folded outermost layer, the cerebral cortex, consists of gray matter, a mass of cell bodies, and fine unmyelinated nerve fibers. Beneath this lies a layer of white matter made up of myelin-covered axons connecting the cerebral cortex with other parts of the brain. Tire two cerebral hemispheres are connected by the corpus callosum, a band of 2 x 108 nerve fibers. Remarkably, these fibers can be completely severed with a relatively minimal disruption of the nervous system. In the past the corpus callosum was sometimes cut to control almost incessant epileptic seizures that could not be prevented by drugs. The "split-brain" patients suffered relatively little disability as long as both eyes functioned normally. Studies of these patients provided some insights into the differing functions of the two hemispheres of the cerebrum.395... 

Fig. 20.3. Dorsal and ventral root dissection. The anatomy of the ventral and dorsal roots during dissection is shown. Mouse is prone (rostral is up) and the left sciatic nerve (Sci) has been exposed along the femur and to its origin at the lumbar spinal nerves. The spinal nerves are labeled (lumbar 3 through 6). The ischium (Isch) has been removed to follow the sciatic nerve. The inset shows the L4 root separated into its ventral and dorsal roots, note the DRG associated with the dorsal root. The scale bar is 6 mm. (Color figure is available online).

Figure 19-5 Sensory nerves of the eyelids. (From Remington LA. Clinical anatomy of the visual system, 2e, Butterworth Heinemann, 2005.)...

This explains the biochemical processes involved, but anatomy also plays a role in movement. The critical spot is the synaptic cleft, the place where the nerve dips into the muscle. Here, the finely branched nerve fiber inserts into a microscopic bit of muscle tissue, and acetylcholine (ACh), the chemical responsible for the transmission of the nerve impulse, hooks onto the muscle fibers, stimulating them to contract. Enough calcium at the site makes the process go more smoothly, while magnesium slows the process. To keep ACh from accumulating in the cells, the en2yme cholinesterase destroys the excess. 

This section reviews basic principles of brain anatomy and function to provide a framework within which to discuss the effect of plants on the CNS. The human nervous system is exceptionally complex, it is the body s major communication system, and is divided into central and peripheral regions. The central nervous system consists of the brain and spinal cord, and the peripheral nervous system consists of all other nerves. Although thought processes and reason are most commonly associated with the CNS, almost every aspect of physiological function is affected by CNS activity. After all, Brain death is widely accepted as the definition of the end of human life 10). The follow description of CNS anatomy and physiology can be foimd in most text books on the and reviews on the subject 11, 17). 

Orte, C.. Lawrenson, J.G, Firm, T.M, Reid, A.R and Allt, G, (1999) A comparison of blood—brain barrier and blood—nerve barrier endothelial cell markers. Anatomy and Embryology, 199, 509-517. 

Olfaction represents a subset of the sense of smell, which this chapter seeks to circumscribe by means of four propositions put forth as guidelines. Of these guidelines, the first is chemical, and the second is behavioral. The third guideline addresses the relationship between anatomy and behavior. Applying it requires that the organism possess a well developed eentral nervous system (CNS). The CNS of terrestrial vertebrates includes a spinal cord and a brain, from which emanates a set of cranial nerves. The first cranial nerve is often called the olfactory bulb. If the connections between the nose and the olfactory bulb are completely severed, the ability to sense and to discriminate among volatile stimuli do not necessarily vanish utterly. Those capabilities that are completely lost, however, include olfaction. 

FIGURE 11.2 Anatomy of the human respiratory tract. Deposition of nerve agent vapor or aerosols in the different regions of the lung can lead to different symptomology. Upper airway deposition can lead to immediate respiratory distress. Alveolar deposition leads to systemic distribution of the nerve agent. 

With these thoughts in mind, we examined the effects of various drugs on GABA-mediated synapses in the crayfish. While there are a number of GABAergic neuromuscular junction preparations in invertebrates which are accessible for physiological research, the crayfish stretch receptor is one of very few invertebrate preparations which can be used for studies of synapses between nerves. The anatomy and physiology of these receptor organs from the abdomen of the crayfish has been extensively studied (6) ... 

In addition to summation of inputs from olfactory nerve terminals, a second function of the circuitry of the glomerular layer is regulation of transmission from the olfactory nerve to mitral and tufted cells. The anatomy of the glomerular layer, reviewed above, provides a basis for such regulation (Fig. 5). 

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