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The risk of pathologic fracture in this patient is great considering its location near the acetabulum and the weight- Clinical Practicum 6 benzac 20 gr for sale. Retropulsion of fracture fragments into the spinal canal causes compression of the spinal cord discount 20gr benzac. Examination of the radiograph shows narrowing of the joint spaces of several is most likely the cauda equina discount benzac 20 gr with mastercard. The injury may be due to compression and of the distal and proximal interphalangeal joints discount 20 gr benzac otc. This joint space narrowing swelling secondary to the fracture or due to damage to the nerves is due to erosion of the articular cartilage. Osteophytes are bony innervating the legs originate at the lumbar and sacral levels of the spine. Soft tissue swelling is also seen around several of the affected joints. The distribution of joint involvement, symptoms, and physical injury, the hamstrings are acting unopposed on the knee. The resting muscle findings are classical for idiopathic osteoarthritis. This is a common tone of the hamstrings holds the knee in a slightly flexed position. They will report pain with use of the affected joints as well as morning stiffness in Clinical Practicum 10. Swelling around the distal interphalangeal joints is a classic physical finding of osteoarthritis known as Heberden’s nodes. Osteoarthritis is a common degenerative disease that affects many joints of 1. This collection of blood is known as an epidural hematoma, and it is usually the body as people age. The most common joints affected include distal and caused by a skull fracture which severs the middle meningeal artery. The arterial proximal interphalangeal joints, wrist, acromioclavicular, hips, knees, and blood collects between the dura mater and the skull. These two boundaries give facet joints of the cervical and lumbar spine. Because the dura mater is adherent to the cranium, it resists being stripped from the bone by the accumulating blood. The head of the humerus has been (lens-shaped) and is characteristic of this type of intracranial hematoma. The initial trauma to the brain in these types of injuries is usually minimial, 2. The dislocation must be reduced by moving the head of the humerus back as evidenced by her brief loss of consciousness. This can be very painful and is often the growing hematoma presses on the brain, raising the intracranial pressure performed under anesthesia, because it requires a great amount of traction on until coma is induced. The expanding hematoma forces the brain to shift toward the opposite side, humerus is correctly positioned. As the brain shifts, the medial portion of the healing of the muscles of the rotator cuff. Because of the structures that pass through the axilla, a dislocation causing the pupil to dilate. Each disc has damage may result in recurrent dislocations of the shoulder, even after minor tough circular fibers which surround and contain a soft jellylike center known as injuries, as well as limited range of motion if rotator cuff injuries occur. In a herniated disc, the soft nucleus pulposus has pushed (herniated) through a weakened area of the fibers to press on a nerve root. A low-density area with peripheral enhancement is seen adjacent to the can also result in numbness/pain and motor deficits specific to the nerve root. By knowing neuroanatomy you can surmise which nerve root is irritated and such as this are suggestive of an abscess. This abscess is closely related to the therefore which disc is herniated: psoas major muscle and does not seem to be related to any of the surrounding organs.
Theviscerocranium(splanchnocranium) is the through a hyaline cartilage stage and then it is ossified as bone trusted benzac 20gr. This typeA smaller number of mesenchymal cells develop into bone processes of the skull discount benzac 20 gr overnight delivery. Clinical Considerations CLINICAL CONSIDERATIONS These special sections appearing at the end of most chapters The clinical aspects of the central nervous system are extensive and usually complex 20 gr benzac amex. Numerous diseases and developmental describe selected developmental disorders discount 20gr benzac visa, diseases, or dysfunctions problems directly involve the nervous system, and the nervous system is indirectly involved with most of the diseases that afflict of specific organ systems, as well as relevant clinical procedures. The the body because of the location and activity of sensory pain re- ceptors. Pain receptors are free nerve endings that are present effects of aging in regard to specific body systems are also profiled. The pain sensations elicited by disease or trauma are important in localizing and diagnosing specific dis- eases or dysfunctions. Only a few of the many clinical considerations of the cen- tral nervous system will be discussed here. These include neuro- Creek logical assessment and drugs, developmental problems, injuries, (a) infections and diseases, and degenerative disorders. Third lumbar vertebra Neurological Assessment and Drugs Coccyx Neurological assessment has become exceedingly sophisticated and Spinal cord accurate in the past few years. In a basic physical examination, only the reflexes and sensory functions are assessed. But if the physician suspects abnormalities involving the nervous system, further neuro- logical tests may be done, employing the following techniques. Acis- needle ternal punctureis similar to a lumbar puncture except that the CSF is withdrawn from a cisterna at the base of the skull, near FIGURE 11. The pressure of the CSF, which is nor- needle between the third and fourth lumbar vertebrae (L3–L4) and mally about 10 mmHg, is measured with amanometer. Samples of (b) withdrawing cerebrospinal fluid from the subarachnoid space. In addi- tion, excessive fluid, accumulated as a result of disease or trauma, may be drained. With that speed, body functions as well as The condition of the arteries of the brain can be deter- structures may be studied. These types of data are important in detecting nique, a radiopaque substance is injected into the common early symptoms of a stroke or other disorders. Aneurysms and vascular constrictions or displacements by ply by examining brain-wave patterns using an electroen- tumors may then be revealed on radiographs. Sensitive electrodes placed on the The development of the CT scanner, or computerized scalp record particular EEG patterns being emitted from evoked axial tomographic scanner, has revolutionized the diagnosis of cerebral activity. The CT scanner projects a sharply focused, de- patients to predict seizures and to determine proper drug therapy, tailed tomogram, or cross section, of a patient’s brain onto a tele- and also to monitor comatose patients. The versatile CT scanner allows quick and The fact that the nervous system is extremely sensitive to accurate diagnoses of tumors, aneurysms, blood clots, and hemor- various drugs is fortunate; at the same time, this sensitivity has rhage. The CT scanner may also be used to detect certain types potential for disaster. Drug abuseis a major clinical concern be- of birth defects, brain damage, scar tissue, and evidence of old or cause of the addictive and devastating effect that certain drugs recent strokes. Much has been written on drug A machine with even greater potential than the CT scan- abuse, and it is beyond the scope of this text to elaborate on the ner is the DSR, or dynamic spatial reconstructor. A positive aspect of drugs is their administration CT scanner, the DSR is computerized to transform radiographs in medicine to temporarily interrupt the passage or perception of into composite video images. Injecting an anesthetic drug near a nerve, as in dimensional view is obtained, and the image is produced much dentistry, desensitizes a specific area and causes a nerve faster than with the CT scanner. Nerve blocks of a limited extent occur if an appendage is cross-sectional images in 5 seconds, whereas the CT scanner can cooled or if a nerve is compressed for a period of time. Before the xx Van De Graaff: Human Front Matter A Visual Guide © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Clinical Practicums These focused clinical scenarios challenge you to put your knowledge of anatomy to work in a clinical setting. Given a brief patient history and accompanying diagnostic images, you must apply the chapter material to diagnose a condition, explain the origin of symptoms, or even recommend a course of treatment.
The globus pallidus generic 20gr benzac amex, or pallidum (CD5) purchase benzac 20gr, is a derivative of the diencephalon generic 20gr benzac with visa. It becomes separated from the other gray regions of the diencephalon as a result of the ingrowing fiber masses of the internal capsule (CD6) during development and finally becomes displaced into the telencephalon discount benzac 20 gr free shipping. Only a small medial rest of the pallidum remains within the unit of the diencephalon; this is Plane of section Kahle, Color Atlas of Human Anatomy, Vol. Subdivision of the Diencephalon, Frontal Section (Optic Chiasm) 173 2 1 1 2 1 2 3 3 4 4 7 7 4 3 A Development of the layers of the diencephalon 1 1 2 6 14 2 3 3 5 4 4 B Structure of the diencephalon in C Structure of the diencephalon in the embryonic brain the adult brain 16 13 10 6 11 12 14 5 17 18 19 9 15 8 D Frontal section through the rostral wall of the third ventricle (according to Villiger and Ludwig) Kahle, Color Atlas of Human Anatomy, Vol. It plex is enclosed by a narrow, shell-shaped covers the dorsal surface of the thalamus nucleus, the reticular nucleus of the (A4), of which only the anterior nuclei are thalamus (B23), which is separated from the visible. Ventrolaterally to it and separated lateral nuclear group by the external medul- by the internal capsule (AB5) lies the globus lary layer (B24). It stands out thalamus with the zona incerta (B25) and the against the adjacent putamen(AB9) because subthalamic nucleus (Luys’ body) (B26). At the basal zona incerta is delimited by two myelinated margin and at the tip of the pallidum there fiber plates, dorsally by Forel’s field H1 exit the lenticular fasciculus (Forel’s field (thalamic fasciculus) (B27) and ventrally by H2) and the lenticular ansa (A10). Its large choliner- gic neurons project diffusely into the entire neocortex. Frontal Section at the Level of the Mamillary Bodies (B) The section shows both thalami; their in- crease in volume has lead to secondary fu- sion in the median line, resulting in the in- terthalamicadhesion(B17). Myelinatedfiber lamellae, the medullary layers of the thalamus, subdivide the thalamus into A B several large complexes of nuclei. Frontal Sections (Tuber Cinereum, Mamillary Bodies) 175 32 14 2 3 4 1 9 16 6 5 8 16 35 7 10 13 11 15 33 12 A Frontal section through the diencephalon at the level of the tuber cinereum (according to Villiger and Ludwig) 18 16 32 3 2 24 14 5 22 21 19 36 23 20 27 17 9 6 31 26 29 13 34 30 28 25 B Frontal section through the diencephalon at the level of the mamillary bodies (according to Villiger and Ludwig) Kahle, Color Atlas of Human Anatomy, Vol. In adults, the sure, and medullary stria), the pineal gland, pineal gland contains large foci of calcifica- and the epithalamic commissure (posterior tion (B14), which are visible on radiographs. In lower vertebrates, the pineal gland is a photo- sensitive organ; it registers changes from light to Habenula (A) dark either by a special parietal eye or just by the light penetrating through the thin roof of the The habenula (A1) (p. By doing so, it influences the day and night ferent and efferent pathways forms a relay rhythm of the organism. For example, it regulates system in which olfactory impulses are the color change in amphibians (dark pigmenta- transmitted to efferent (salivatory and tion during the day, pale pigmentation at night) motor) nuclei of the brain stem. The pineal gland also registers the trans- olfactory sensation is thought to affect food ition from bright summertime to dark wintertime intake. The habenular nucleus contains and thus brings about seasonal changes in the numerous peptidergic neurons. The afferent pathways reach the habenular In higher vertebrates, the light does not penetrate nuclei via the medullary stria of the thalamus the thick roof of the skull. It contains fibers from the septal nuclei night is transmitted to the pineal gland through (A3), the anterior perforated substance (ol- the following route: via retinal fibers to the su- factory area) (A4), and the preoptic region prachiasmatic nucleus in the hypothalamus, then via efferent hypothalamic fibers to the interme- (A5). The efferent pathways extend into the mid- In humans, the pineal gland is thought to inhibit brain. The habenulotectal tract (A8) transmits maturation of the genitals until puberty. Hypergonadism has been observed in in the dorsal tegmental nucleus (A10), from some cases of pineal gland destruction in children. Not all fiber systems that pass the masticatory and deglutitory muscles through the epithalamic commissure (B15) (olfactory stimuli leading to secretion of are known. The habenulo-inter- From the various pretectal nuclei that send peduncular tract, Meynert’s bundle (A11), ter- fibers through the commissure, the intersti- minates in the interpeduncular nucleus tial nucleus of Cajal and Darkshevich’s nu- (A12) (p. Itscells,thepinealocytes,aregrouped into lobules by connective tissue septa. Habenula and Epiphysis 177 7 2 1 3 4 5 11 13 17 9 8 16 18 12 6 10 20 A Fiber connections of 14 the habenula 19 15 B Pineal gland C Pinealocytes, silver impregnation D Histological appearance of the pineal gland, (according to Hortega) silver impregnation (according to Hortega) Kahle, Color Atlas of Human Anatomy, Vol. Their medial surfaces form clei are subdivided into the following nu- the wall of the third ventricle, while their clear groups (or complexes): lateral surfaces border on the internal cap-!
STRIATUM The concentration of ACh in the striatum is the highest of any brain region generic benzac 20 gr with visa. It is not affected by de-afferentation but is reduced by intrastriatal injections of kainic acid and so the ACh is associated with intrinsic neurons buy discount benzac 20 gr. Here ACh has an excitatory effect on other neurons mediated through muscarinic receptors and is closely involved with DA (inhibitory) function safe benzac 20gr. Thus ACh inhibits DA release and atropine increases it order benzac 20 gr online, although the precise anatomical connection by which this is achieved is uncertain and the complexity of the interrelationship between ACh and DA is emphasised by the fact that DA also inhibits ACh release. In view of the opposingexcitatory and inhibitory effects of ACh and DA in the striatum and the known loss of striatal DA in Parkinsonism (see Chapter 15) it is perhaps not surprisingthat antimuscarinic agents have been of some value in the treatment of that condition, especially in controllingtremor, and that certain muscarinic agonists, like oxotremorine, produce tremor in animals. CORTEX Cholinergic neurotransmission has been most thoroughly studied in the cortex where the role of ACh as a mediator of some afferent input is indicated by the findingthat undercuttingthe cortex leads to the virtual loss of cortical ACh, ChAT and cholinesterase. That it is not the mediator of the primary afferent input has been shown by the inability of atropine to block the excitatory effect of stimulatingthose pathways and the fact that such stimulation causes a release of ACh over a wide area of the cortex and not just localised to the area of their cortical representation (see Collier and Mitchell 1967). Indeed there have been many experiments which show that the release of ACh in the cortex is proportional to the level of cortical excitability, being increased by a variety of convulsants and decreased by anaesthesia (Fig. The origins of this diffuse cholinergic input have been traced in the rat to the magnocellular forebrain nuclei (MFN) by mappingchanges in cortical cholinesterase and ChAT after lesioningspecific subcortical nuclei. The most important of them appears to be the nucleus basalis magnocellularis, similar to the nucleus of Maynert in humans, which projects predominantly to the frontal and parietal cortex and is thought to be affected ACETYLCHOLINE 133 Figure 6. Correlation between acetylcholine release and EEG activity after injections of leptazol (LEP mgkgÀ1 intravenously) into the urethane anaesthetised rat. ACh was collected in a cortical cup incorporatingEEG recordingelectrodes. This nucleus, together with the diagonal band, forms the sub- stantia innominata and the dorsal neurons of this band also join with those in the medial septum to provide a distinct cholinergic input to the hippocampus (Fig. There is a second group of cholinergic neurons more caudally in the pontine teg- mentum, the pendunculo pontine tegmental nucleus (PPPTN) and a smaller laterodorsal tegmental nucleus (LDTN). Despite the excitatory effect of ACh in the cortex and its increased release during convulsive activity, antimuscarinic agents have only a slight sedative action (indeed, as emphasised above, atropine may cause excitation) and no anticonvulsant activity, except possibly in reducingsome forms of experimentally induced kindling. ACh appears to exert a background excitatory effect on cortical function and while it may not directly stimulate the firingof pyramidal cells it will sensitise them to other excitatory inputs through its muscarinic activity. If this pathway is lesioned the cortical EEG becomes quiescent but when stimulated it produces a high-frequency low-voltage desynchronised (aroused) EEG, which can be countered by antimuscarinic and potentiated by anticholinesterase drugs. Unfortunately this does not seem to apply to the actual behavioural arousal produced by such stimulation and suggests that ACh does not have a primary and certainly not a unique role in the maintenance of consciousness or sleep, although the firingof forebrain cholinergic neurons increases duringthe transition from sleep to waking. ACh does, however, feature prominently in one aspect of sleep behaviour. This so-called slow-wave sleep is interrupted at intervals of some 1±2 h by the break-up and desynchronisation of the EEG into an awake-like pattern. Since this is accompanied by rapid eye movements, even though sleep persists and can be deeper, the phase is known as rapid eye movement, REM or paradoxical, sleep. More importantly, for this discussion, it can be intensified by anticholinesterases and reduced by antimuscarinics and it is accompanied, and in fact preceded, by burst firing of a group of cholinergic neurons in the pedunculo pontine tegmental nucleus (PPTN). Neurons from this nucleus, which is quite distinct from the nucleus basalis, project to the paramedian pontine reticular formation, the thalamic lateral geniculate body and thus to the occipital cortex, all of which show increased activity during REM sleep to give PGO (ponto±geniculo±occipital) waves. Clearly sleep is not just a passive event and while cholinergic activity may be important in the production of REM sleep it does not appear to be responsible for turningit off or for actually inducingsleep. COGNITION AND REWARD Not only is REM sleep a time for dreamingbut it is also believed to be a time for the layingdown (consolidation) of memory. This is only one observation amongmany that implicates ACh in the memory process. Certainly antimuscarinic drugs like atropine are well known to impair cognitive function in both animals and humans. In the former antimuscarinic drugs appear to impair both the acquisition and retention of some learned tasks, as in the Morris water maze. This involves placinga rat in a circular tank of water containinga stand with a platform just below the surface but which is not clearly visible because the vessel walls or water have been made opaque. Generally the rat quickly learns (2±3 trials) to identify the position of and swims to the platform. That ability is impaired by pretreatment with antimuscarinics which increase the number of ACETYLCHOLINE 135 trials (possibly tenfold) required before the animal swims directly to the platform and can increase the time to achieve it if given after the task has been learnt.